Anatomy of the Saccade System

Three important cortical areas are involved with saccade generation and include the frontal eye fields (FEF), the supplementary eye fields (SEF), and the parietal eye fields (PEF). Other zones of the association cortex that play a secondary, but important role in saccade generation are the prefrontal cortex (PFC) and posterior parietal cortex. The interrelationships of these structures are complex and are summarized with a clinical emphasis (Fig. 9-6 (Figure Not Available) ). 8 The FEF is...

Table 3410 Startle Syndromes

Mutations in the alpha-1 subunit of the inhibitory glycine receptor, which is localized to chromosome 5q. 86 The hallmark of hyperexplexia is an exaggerated startle response to a sudden, unexpected stimulus. Children with hyperexplexia are born with continuous stiffness and demonstrate a flexor posture, both of which disappear with sleep. Severely affected children startle excessively to sudden stimuli, and infants characteristically flex rather than extend their arms as seen with the normal...

Abnormal Findings and Clinical Uses of the BAEP

The BAEP is an important means of evaluating function of the eighth cranial nerve and the central auditory pathways in the brain stem. In infants, young children, and adults who are unable to cooperate for behavioral testing, BAEPs can be used to evaluate hearing. y The wave V component of the response is generated by auditory stimuli that are too weak to generate other components. As a screening test of hearing, then, the electrophysiological threshold for eliciting wave V is determined. An...

Neuromuscular Junction Syndromes

The defect in neuromuscular transmission in myasthenia gravis (see Chapter 50 ) produces a pure muscular weakness without the atrophy, fasciculations, or reflex changes seen in motor neuron disease.y Myasthenia gravis also causes a pattern of weakness in the ocular and cranial muscles that is different from that seen in amyotrophic lateral sclerosis. A weakness of the extraocular muscles and eyelids producing diplopia and ptosis is common in patients with myasthenia gravis but rare in those...

Normal Pressure Hydrocephalus

NPH is the result of an imbalance between production and resorption of the CSF, usually around the brain convexities. Whereas there is full communication between the ventricles and the subarachnoid space (communicating hydrocephalus), the communication between the subarachnoid space and the arachnoid villi and granulations is not intact, so fluid is not transferred efficiently to the superior sagittal sinus. Subarachnoid hemorrhage, meningitis, head trauma, and...

Pontine and Medullary Dysfunction

Hemorrhage into the basis pontis frequently extends rostrally into the midbrain and appears to produce coma by interference with midbrain reticular function. This condition is associated with pinpoint pupils, presumably reflecting both parasympathetic irritation as well as sympathetic outflow disruption. Importantly, however, most patients presenting in coma with pinpoint pupils are suffering from an opiate overdose and not specific pontine dysfunction. Naloxone quickly reverses opiate...

Tissue Selection and Techniques

Diagnostic brain biopsy is usually performed as stereotactic biopsy or open craniotomy. y Stereotactic brain biopsy, using computerized tomography or magnetic resonance imaging guidance, is usually completed by the aspiration of tissue through a needle inserted into the area of the lesion. Although this technique is particularly useful in cases in which the lesion is small, deep-seated, or located in a sensitive area such as the motor cortex or deep nuclei, the amount of tissue removed is small...

Whipples Disease

Whipple's disease is caused by the rod-shaped bacillus Tropheryma whippelii and presents with arthralgias, abdominal pain, fever, diarrhea, malabsorption, and weight loss.y , y Whipple's disease occurs predominantly in middle- aged men and most often in farmers. Approximately 6 to 7 percent of patients with Whipple's disease have neurological manifestations, but many cases of CNS involvement in Whipple's disease go unrecognized. y The characteristic triad of Whipple's disease is dementia,...

Oculopharyngeal Muscular Dystrophy

Oculopharyngeal muscular dystrophy is a disorder of late adult onset characterized by progressive ptosis and dysphagia. The region of chromosome 14q11.2-q13 with the cardiac and beta myosin heavy chain genes is the locus of the causative gene in three French Canadian families. y Although the highest prevalence of oculopharyngeal muscular dystrophy continues to be in Quebec, which is most likely the result of a founder effect, families have now been identified in more than 20 countries....

Types of Memory

Memory in health and disease has been the focus of medical studies throughout history. In the first century, Pliny the Elder described a man who fell off a roof and afterward could not remember his mother, neighbors, and friends. Galen (130-200) placed emphasis on the ventricles as the anatomical key to mental processing, a view advocated by Nemesius of Syria, Posidonius of Byzantium, and several other early religious leaders whose views influenced medical thought. The perceived role of the...

Parasomnias

The term parasomnia refers to a group of disorders of arousal, partial arousal, and sleep-stage transition. A feature of many of the parasomnias is the occurrence of abnormal muscle activation behaviors occur during sleep. These behaviors may be associated with REM or NREM sleep. Behaviors occurring predominantly during the first third of the night are likely to be related to Stages 3 and 4 sleep because this is the time of night when SWS predominates and are largely considered disorders of...

Herniation Syndromes

Herniation occurs when the brain is subjected to pressure gradients that cause portions of it to flow from one intracranial compartment to another. Although the brain has substantial elasticity, the arteries and veins responsible for its blood supply are relatively fixed in space, producing a risk that brain shifts will cause the moving portions to lose their blood supply. In the case of lateral herniation, the hernia itself may compress or distort vessels, similarly disrupting blood flow....

Internuclear Oculomotor Control The Final Common Pathway

Zones within the tegmental reticular formation in the brain stem serve to combine the various eye movement commands and to present an integrated set of final motor commands to the ocular motor nuclei. The PPRF refers to the zone surrounding cranial nerve Vi nucleus on either side of midline in the pontine tegmentum. This area contains burst and pause cells that are important for horizontal saccade generation. The rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), the...

Abnormal Findings and Clinical Uses of the VEP

Visual evoked potentials are useful in evaluating the function of the anterior visual pathways. They are not useful in evaluating lesions posterior to the optic chiasm. In patients with an acute optic or retrobulbar neuritis, the P100 response is initially lost with time, it recovers and is then found to have a markedly prolonged latency that generally persists indefinitely (see Fig, 24-1.2. ), 23 , 2i even if apparently complete clinical recovery occurs. The VEP is therefore an important means...

Chickpea Lathyrism

Lathyrism is related to a neurotoxin acting through the glutaminergic system. Spastic paraplegia has been observed in Europe and India following consumption of different varieties of chickpea. Development of human lathyrism is associated with two potent neurotoxins found in the peas alpha-amino beta oxalylaminopropionic acid and alpha-amino gamma oxalylaminobutyric acid.y Toxic neurological signs are seen when 30 percent or more of the diet consists of chickpeas. Men tend to be affected more...

Spinocerebellar Pathways

A second type of sensory information enters the spinal cord through the dorsal columns. These fibers generally carry spinocerebellar impulses that terminate in various regions of the cerebellum and thus do not reach a level of conscious sensation. The dorsal spino-olivary tract ascends within the dorsal columns, synapses in the cuneatus and gracilis nuclei, and then relays impulses to the contralateral accessory olivary nucleus. These fibers arise in the spinal cord and are activated by...

Degenerative Muscular Disorders

The muscular dystrophies are hereditary, degenerative dystrophinopathies and disorders of dystrophin-associated proteins. In 1987, with the identification of a defect in the dystrophin gene as the cause of Duchenne muscular dystrophy (DMD), Monaco and Kunkel opened the door TABLE 36-4 -- FAMILIAL SPASTIC PARAPLEGIA (SPG), GE AR, Autosomal recessive AD, autosomal dominant, LICAM, L1 cell adhesion molecule. for research into its role in muscle function and maintenance. Dystrophin is controlled by...

Perception and Construction Abilities

The ability to perceive stimuli is one of the basic requirements for the assessment of cognitive function. Therefore, tests of visual, auditory, and tactile perception are common in neuropsychological assessments. Certain alterations in perception, such as neglect, are diagnostically informative. Tests of visual perception typically assess color perception, object recognition, visual organizational abilities, visual scanning, and differentiation of figure from ground. Most neuropsychological...

Hereditary Sensory and Autonomic Neuropathies

The hereditary sensory and autonomic neuropathies (HSANs) are conditions in which primary sensory and autonomic neurons either fail to develop or undergo system atrophy and degeneration. Dyck proposes the comprehensive subdivision seen in Table.36.-10. . These disorders have been called by a large variety of names because their symptoms were described by various investigators. Types I, II, and III are discussed here. Within this classification there are two large divisions HSAN I is a...

Corticobasal Ganglionic Degeneration

The characteristic pathological changes in CBGD include asymmetrical frontoparietal cortical atrophy with corresponding neuronal loss and gliosis, substantia nigra degeneration, and swollen achromatic neurons. ioo Variable degrees of degeneration in other subcortical nuclei also occur. The achromatic neurons immunostain positively to neurofilaments (.Fig 33-12. ). Some have regarded these neurons to be related to Pick cells, although immunohistochemical and...

Central Autonomic Network

The ANS, like the somatic nervous system, is organized in segmental levels. Neurons in the cerebral cortex, basal forebrain, hypothalamus, midbrain, pons, and medulla participate in autonomic control. Autonomic neurons are reciprocally interconnected by neurochemically complex pathways and constitute a functional unit referred to as the central autonomic network (CAN).y , 4 The CAN integrates visceral, humoral, and environmental information to produce coordinated autonomic, neuroendocrine, and...

Sensory Receptors and Primary Neurons

Cranial nerve I is the collection of approximately 6 million bipolar receptor cells whose cell bodies, dendrites, and initial axon segments are located within the olfactory neuroepithelium and whose axons project through the cribriform plate of the ethmoid bone to the anterior cranial fossa (Fig. 7-1 (Figure Not Available) ). 4 The olfactory neuroepithelium is a pseudostratified columnar epithelium supported by a highly vascularized lamina propria and is situated on the cribriform plate as well...

Primary CNS Lymphoma

The reason for the increase in primary CNS lymphoma (PCNSL) in the immunocompetent and immunocompromised population is unknown. Because there are no lymphatics in the CNS, the mechanism for neoplastic transformation remains unknown. Viral causes have been suggested. In studies of AIDS-related PCNSL, the Epstein-Barr virus was found in a majority of cases, y but this was not found in samples analyzed from immunocompetent patients. Herpes virus type 6 has also...

Cockaynes Syndrome

Cockayne's syndrome (see Tab e.3.0.-6. ) is sometimes classified as a variant of Pelizaeus-Merzbacher disease because of the similar pattern of patchy demyelination among preserved islands of myelin.y However, in this disease there is pronounced involvement of multiple systems, suggesting a different pathogenic mechanism. The brain is small, and the white matter is atrophic. Calcifications are frequently Proteolipid apoprotein in defect in gene Xq22 on X-chromosome Psychomotor retardation,...

Hereditary Sensory and Motor Neuropathies

In general, the hereditary sensory and motor neuropathies are peripheral neuropathies that affect either autonomic nerves, sensory nerves, motor fibers, or a combination thereof. The molecular genetics of these disorders is being ardently pursued and the mechanisms underlying them are rapidly being unraveled. However, to date there is overlapping terminology used when they are described (ii,Xa.b e.,36 8 ). This discussion is organized according to the classification that is emerging based on...

Directed Neurological Examination

The directed neurological examination should begin with a mental status evaluation, which includes a psychiatric assessment. This part of the examination actually begins during the history and may be expanded in a more formal fashion. The mental status examination should include assessments of level of alertness, orientation, and attention. Stupor may be organic in origin or psychiatric. Hypervigilant states may develop with delirium tremens as well as with drug overdoses, such as amphetamine,...

Parkinsonism Plus Syndromes

In addition to Parkinson's disease, parkinsonism is one of the major clinical features in several other primary neurodegenerative conditions. However, because they all have additional features not typical of Parkinson's disease and share an overall worse prognosis and poorer response to antiparkinsonian therapy, they are often grouped together under the conglomerate term parkinsonism-plus syndromes. Within this group, each condition has distinctive characteristics that must be recognized and...

Methylphenyltetrahydropyridine

The first case of methyl-phenyl-tetrahydropyridine (MPTP)-induced parkinsonism was reported in 1979. y The subject later died of a drug overdose. At autopsy, destruction of the substantia nigra zona compacta was evident other areas usually involved in Parkinson's disease such as the locus coeruleus were not affected. This article lay dormant until parkinsonism began appearing in the San Francisco Bay area among users of MPTP sold as synthetic heroin. The responsible chemical was identified as a...

Fungal Infections

As a general rule, fungal infections occur in individuals who are immunosuppressed as a result of (1) AIDS (2) organ transplantation (3) immunosuppressive chemotherapy or chronic corticosteroid therapy and (4) chronic disease. The single exception to this generalization is cryptococcal meningitis, which may occur in healthy individuals. The fungus-causing infection can be predicted to some degree based on the predisposing condition. For example, individuals with AIDS are at risk for meningitis...

Impulse Dyscontrol and Aggression Syndromes

The impulse dyscontrol and aggression syndrome consists of an inability to resist an impulse to perform a harmful act the impulse is accompanied by a buildup of tension needing to be released, and is followed by a feeling of satisfaction or relief when the act is committed. This in turn is followed by either relief, remorse, or a sense of justification for the act. Impulse dyscontrol and aggression can occur in neurologically normal individuals, but this behavior becomes pathological when...

Hypokinesia Syndromes Table164

The term hypokinetic syndrome is synonymous with parkinsonism. In addition to slowness, parkinsonism, as a clinical syndrome of multiple etiologies, is manifested by combinations of several cardinal symptoms and signs ( J bJe 16-5 ). At least two of the cardinal features should be present before the syndromic diagnosis of parkinsonism is made, with one of them being hypokinesia or tremor at rest. Parkinsonism can occur in isolation without other neurological signs, or can occur as part of a...

Muscle strength

Active movement, with gravity eliminated Active movement against gravity and resistance From Medical Research Council Aids to the Examination of the Peripheral Nervous System Memorandum No. 45. London, Crown Publishing, l976 discover whether there is a particular pattern of weakness that can be used to localize the lesion. Is it a hemiparesis, suggesting a hemispheric lesion, a paraparesis, which is consistent with a spinal cord lesion, or a proximal pattern of weakness compatible with a...

Special Autonomic Function Testing

Many laboratory tests are used to diagnose autonomic disorders, quantify autonomic function, and evaluate the efficacy of treatment. Disorders for which autonomic testing provides useful information include those involving generalized autonomic failure such as the Shy-Drager syndrome, Parkinson's disease, and pure autonomic failure, suspected distal small-fiber and other peripheral neuropathies, orthostatic intolerance of uncertain etiology, syncope, localized autonomic disorders, unexplained...

Malignant Hyperthermia

Malignant hyperthermia is a hereditary skeletal muscle disease characterized by a hypercatabolic reaction of muscle to anesthetic agents or to physical or emotional stress. Pathogenesis and Pathophysiology. The central event in malignant hyperthermia appears to be an increase in the calcium concentration, which results in continuous activation of the actin-myosin contraction apparatus and sustained muscle contraction. This increase in calcium level is due to an increased release of calcium from...

Directed Neurological Examination Assessment Of Muscle Bulk

The patient should be in a state of sufficient undress for the physician to be able to appreciate his or her general bodily habitus and especially the muscle bulk of the extremities. Before actual testing of muscle strength begins, simple observation may disclose asymmetries in muscle bulk of the extremities or more focal atrophy of specific muscles or muscle groups. The upper extremities should be inspected in both the pronated and supinated positions, which is especially important to...

Upper Motor Neuron Pool

There are many neurons in the cerebral cortex and brain stem that initiate and modify movement through their connections with the lower motor neurons in the anterior spinal gray. These projections also synapse on the internuncial pool of interneurons. which in turn make contact with the alpha and gamma motor neurons. These are known as the upper motor neurons. These supraspinal motor neurons in the cerebral cortex and brain stem are interconnected with each other and participate to various...

Amphetamine Analogs

The pathophysiological basis for the complications associated with amphetamine use are not well understood. Amphetamine-induced cerebral vasculitides cause occlusive as well as hemorrhagic strokes. Methamphetamine use can cause necrotizing angiitis. Also, cerebral arteritis with multiple occlusions of arterioles was reported in young abusers of intravenous methamphetamine who were hospitalized because of coma or stroke. y Angiographic studies in such patients...

Degenerative and Compressive Structural Disorders

History and Definitions Degenerative Structural Disorders Degenerative Disc Disease Cervical Spondylosis Ankylosing Spondylitis Compressive Structural Disorders Fibrous Dysplasia Paget's Disease Other Compressive Disorders Compressive Neuropathies Reviews and Selected Updates References A variety of neurological disorders result from abnormalities of bones, ligaments, muscles, and other mesenchymal tissue that compress the nervous system. In many instances the result is a focal disorder of...

Isaacs Disease

In this syndrome, neuromyotonia or hyperexcitability of the peripheral nerves results in spontaneous and continuous muscle electrical activity. Although in some cases the disease is inherited, in the majority it is acquired. The continuous discharges may originate anywhere along the length of the peripheral nerve. There is some association between Issac's syndrome and autoimmune disease, and it is thought that the acquired varieties are autoimmune in origin. In support of this idea, antibodies...

Directed Neurological Examination Cranial Nerve Xi

The examination of cranial nerve (CN) XI consists of two parts observation (at rest and during action) and palpation. Abnormal findings include atrophy fasciculations neck or shoulder deviation and limitations in range, strength, or speed of motion. Examiners should observe the neck and back while the patient is seated or standing, paying particular attention to the SCM muscle and the upper portion of the trapezius muscle. Atrophy or asymmetry should be noted. Fasciculations may be present with...

Progressive Aphasia

The degenerative focus centers on anterior perisylvian language cortices (Broca's area). Neuropathology of progressive aphasia has included (1) nonspecific degenerative changes, including increased neuronal lipofuscin, y neuronal loss, astrocytosis, and peri- neuronal microvacuolation in superficial laminae with or without occasional amyloid plaques y (2) nonspecific degenerative changes with focal accumulations of achromatic BLE 12-2 -- ASYMMETRICAL CORTICAL DEGENERATION...

REM Sleep

The anatomical substrates for the different components of REM sleep are as follows 1. An important substrate is cortical desynchronization. The origin of the mixed frequency activity is the mesencephalic reticular formation. The reticular cells fire about 15 seconds before activation of cortex, and their projections extend to the intralaminar nuclei of the thalamus with widespread projections to cortex. 2. Hippocampal theta activity is highly synchronous activity with a frequency of 5 to 10 Hz,...

References

Haymaker W, Baer K The Founders of Neurology. Springfield, il, Charles c Thomas, 1953, pp 356-35 . 2. Levinson, A Cerebrospinal Fluid in Health and Disease. St. Louis, c.v. Mosby, 1929 3. Dandy WE, Blackfan KD Internal hydrocephalus. An experimental, clinical and pathological study. Am j Dis Child 1914 8 406-482 4. Cushing H Studies on cerebrospinal fluid. j Med Res 1914 31 1-19 5. Ames A, Sakanoue M, Endo S Na, K, Ca, Mg and Cl concentrations in the choroid plexus fluid and the cisternal fluid...

Unknown Inheritance Patterns

Sturge is credited with the first report of this syndrome, which appeared in a 6-year-old girl who had a facial angioma, buphthalmos, and contralateral partial seizures.y Sturge surmised that she had an underlying cerebral angioma, but it was not until 18 years later that a cerebral angioma affecting the leptomeninges of these patients was first described. Weber reported the presence of intracranial calcifications in skull radiographs of these patients, Dimitri noted double serpentine...

Abnormal Findings and Clinical Uses of the Blink Reflex

The blink reflex may be helpful in revealing the presence of a subtle trigeminal or facial nerve lesion. Ipsilateral trigeminal nerve lesions lead to responses that are either lost or have a prolonged latency bilaterally. A unilateral facial nerve lesion, by contrast, leads to a delayed or absent response on the affected side regardless of which side is stimulated. The blink reflex may be abnormal with polyneuropathies, thereby indicating the extent of the disorder. Abnormalities may also occur...

Etiology Percent

Jejunal diverticula 2 Dietary cobalamin malabsorption Intrinsic factor antibodies present, or, correction of abnormal Part I Schilling test with intrinsic factor Evidence of achlorhydria (elevated serum gastrin) with abnormal Part I Schilling test in some, but evaluation incomplete. Evidence of achlorhydria (elevated serum gastrin) with abnormal Part I Schilling test. Reprinted with permission from Healton EV, Savage DG, Brust JCN, et al Neurologic aspects of cobalamin deficiency. Medicine...

Measles

Measles is one of the three major infectious diseases worldwide and causes about 1.5 million childhood deaths per year. y In the 1960s, prior to routine childhood immunization, more than 400,000 cases of measles were reported annually in comparison, less than 4000 cases were reported annually in the early 1980s. From 1988 to 1990, the incidence of measles increased eightfold. y Between 1987 and 1990, 52,846 cases of measles were reported to the CDC.y This marked...

Other Peripheral Nerve Tumors

Benign tumors of the peripheral nerves are often localized to single sites and are related to pressure or trauma. For example, Morton's neuroma is commonly associated with increased pressure or tight-fitting shoes and represents fibrotic swelling of the nerve in response to repeated insult. Located on the plantar surface of the foot, it is treated with excision or observation. Symptoms include localized pain, tenderness, and weakness of the distally affected muscles innervated by the nerve....

Basic Principles and Technique

Stimulation of a mixed nerve or its sensory branch leads to a response that can be recorded from the nerve more proximally or distally (the sensory nerve action potential), as well as over the spine and scalp. The scalp response is small and obscured by the ongoing EEG, and for this reason it is often necessary to average up to 2000 responses after stimulation of a nerve in the arm or 4000 responses with stimulation of a nerve in the leg, depending on the amount of background noise, to obtain...

Associated Neurological Findings

Because the basal ganglia circuits include the cortex and because the caudate nucleus is particularly involved with cognition, the cerebral examination can have important contributory findings in patients with hypokinesia or hyperkinesia. Bedside screening tests of dementia and depression are very useful, and an assessment of aphasia and apraxia indicates likely cortical lesions. Cranial Nerves. Most cranial nerve functions are retained in hypokinesia and hyperkinesia. Ocular saccades...

Evaluation Guidelines Table156

A wide variety of tests are now available to the neurological clinician. The work-up must be tailored to the situation and guided by a careful analysis of the neurological examination and history. The findings on the neurological examination localize the lesion to the nervous system and to the area where the attention should be focused. They also narrow the possible causes of the disorder. The list of possible causes is narrowed further by the history, which gives the clinician the temporal...

Neurological Applications in Diagnosis and Treatment

One of the primary uses of MRA is the evaluation of the lesions in the carotid artery bifurcation. Atherosclerotic lesions within the carotid bulb and proximal internal carotid artery are major factors contributing to the development of cerebrovascular ischemia. The appropriate treatment of patients with asymptomatic and symptomatic carotid stenosis remains controversial. The North American Symptomatic Carotid Endarterectomy Trial y and the European Carotid Surgery...

Memory See ChaptersS and

The ability to record, retain, and reproduce information constitutes memory functioning. Memory is not a unitary phenomenon, however. There are different forms of memory ( Table ,.27. 2. ) including memory requiring awareness (explicit memory) as well as memory that occurs in the absence of awareness (implicit memory) (see Chapt .L5. ). All standard clinical assessments of memory test explicit memory. Even within explicit memory there are different forms. Semantic memory represents the ability...

Anatomy of Arousal

Arousal requires the interplay of both the reticular formation and the cerebral hemispheres. The reticular components necessary for arousal reside in the midbrain and diencephalon the pontine reticular formation is not necessary for arousal. The midbrain may be viewed as a driving center for the higher structures loss of the midbrain reticular formation (MRF) produces a state in which the cortex appears to be waiting for the command or ability to function. This is manifested...

Discriminative Touch Vibration and Conscious Sense of Joint Muscle Movement

There are three elements of proprioception with separate peripheral receptor representation (1) the perception of limb movement is mediated by muscle spindle receptors, cutaneous mechanoreceptors, and joint receptors (2) the perception of limb position is mediated by muscle spindle receptors and cutaneous mechanoreceptors and (3) the perception of force of muscular contraction is mediated by corollary discharges and tendon organ receptors. y Specific mechanoreceptors that have been implicated...

Syndrome of Acute Generalized Weakness

Occasionally the pace of a disease is so rapid that by the time the patient is seen in the hospital the weakness has become generalized. The history of the mode of onset and the early course of the disease may not be available or may be confused by inaccurate observations. Therefore, accurate formulation of the problem depends on the examination and on localization of the level of the motor system that is damaged and is producing the weakness (see Table 15.-.14. ). The first step in the...

Gastrointestinal Dysmotility

The principles of management of any gastrointestinal motility disorder include restoration of hydration and nutrition by the oral, enteral, or parenteral route, suppression of bacterial overgrowth, use of prokinetic agents or stimulating laxatives, and resection of localized disease. Bowel Hypomotility. The first line of treatment of bowel hypomotility is to increase dietary fiber as well as water intake and exercise. Psyllium or methylcellulose with a concomitant increase in fluid intake may...

Reviews And Selected Updates

Leigh JR, Zee DS The Neurology of Eye Movements, 2nd ed. Philadelphia, F.A. Davis Company, 1991. Miller NR Walsh and Hoyt's Clinical Neuro-Ophthalmology, 4th ed, Vol 2. Baltimore, Williams & Wilkins, 1985. Pierrot-Deseilligny C, Rivaud S, Gaymard B, et al Cortical control of saccades. Ann Neurol 1995 37 557-567. Pierrot-Deseilligny C Saccade and smooth-pursuit impairment after cerebral hemispheric lesions. Eur Neurol 1994 34 121-134. Pierrot-Deseilligny C Brainstem control of horizontal gaze...

Neuropathy Ataxia Retinitis Pigmentosa Syndrome

The neuropathy, ataxia, retinitis pigmentosa (NARP) syndrome is due to a point mutation at bp8993 in the ATPase 6 gene (MTATP6*NARP8993), which changes a highly conserved leucine at position 156 to an arginine. The exact incidence is unknown, but this is a rare, functionally recessive, with variable systemic expression, adult-onset progressive disease. Presentation is with neuropathy or neurogenic weakness, ataxia, and pigmentary retinopathy. It can also be associated with dementia, generalized...

Abnormal Findings and Clinical Uses of the SEP

Somatosensory evoked potentials are helpful in detecting and localizing lesions of the somatosensory pathways within the CNS but provide no indication about the nature of the underlying pathological processes. They are of little value in evaluating the peripheral nervous system, except when there is concern about the functional integrity of nerves Figure 24-14 Median-elicited somatosensory evoked potential elicited A, a normal subject by right-sided stimulation, anB, a patient with multiple...

Spinal Cord Tumors

Although rare, spinal cord tumors continue to carry a grave prognosis for patients. They are difficult to resect and treat. Both the tumor itself and the treatment often lead to profound physical and neurological disability due to spinal cord damage. Spinal cord tumors represent about 7 percent of all primary tumors of the CNS and are seen more commonly in children, in whom they represent up to a fourth of all intra-axial tumors by location. The most common histological type is that of the...

Dorsal Root Ganglion Dorsal Horn Lesions Tabes Dorsalis

Generalized sensory neuropathies should be distinguished from subacute sensory neuronopathies, which are characterized by pain, paresthesia, and numbness in the limbs. The latter demonstrate a marked loss of proprioception and vibration, ataxia, and areflexia in an entire limb with a loss of pain and temperature to a lesser degree. The sensory loss may be more pronounced in the upper extremities than the lower extremities therefore, it is not strictly length dependent, distinguishing it from a...

Epstein Barr Virus

Epstein-Barr virus (EBV) is a human B-lymphotropic virus, the causative agent of infectious mononucleosis. The major route of transmission of EBV is through saliva, and EBV infects the epithelial cells of the oropharynx and adjacent structures as well as those of the uterine cervix. Epithelial cells may play a major role in the persistence of EBV by allowing chronic viral replication and release of infectious particles throughout the lifetime of a virus-infected...

History And Definitions

The modern study of neurovascular function owes much of its success to important, early contributors to the field. Some of the earliest drawings of the cerebral circulation were done in the 1500s by Andreas Vesalius. 1 Gabriel Fallopius provided a detailed description of the cerebral vasculature, including a description of what was later called the circle of Willis. 1 Thomas Willis was the first to describe the function of the circle that bears his name. 1 Vascular anatomy was transformed into...

Comments

Normally, the cerebral cortex triggers another breath within 10 seconds regardless of the PaCO2 1. Periods of apnea are actually times when the respiratory amplitude is too low to measure, but the respiratory rhythm is unchanged 2. Congestive heart failure prolongs the reflex are (blood leaving the lungs takes longer to reach the brain stem than is normal) and may produce this finding without any neurologic dysfunction When present in patients with brain stem lesions or subarachnoid hemorrhage,...

Normal and Pathological Findings see Tables262 263 and 264

The general appearance of CSF is clear and colorless, because it is more than 99 percent water. Color of CSF is observed only in pathological circumstances. Whereas the term xanthochromia means yellow color, it has been used for the presence of other colors as well. Because of this practice, the actual color of the CSF should be stated and a gradation of its magnitude (from 1+ to 4+) should be noted. A yellowish tinge can be found with any cause of a markedly increased protein (greater than 200...

Limbic System

The term limbic lobe was coined by Broca in 1878 to describe a series of structures that envelop the brain stem. The word limbic is derived from limbus, meaning border in Latin, 5 and the limbic system encompasses the amygdala, hippocampus, septum, cingulate gyrus, cingulate cortex, hypothalamus, epithalamus, anterior thalamus, mammillary bodies, and fornix. The limbic system has rich connections throughout the brain, particularly with the primary sensory cortices, including the rhinencephalon...

Spinal Cord Strokes

Spinal cord infarcts are most often caused by interruption of the blood flow in one or more of the arteries that feed into the anterior spinal arterial system. A large anterior spinal artery runs in the ventral midline from the medullospinal junction rostrally to the conus medullaris and the filum terminale caudally. This anterior spinal artery system is supplied by five to 10 single radicular arteries. The cervical region is supplied by the anterior spinal...

Metachromatic Leukodystrophies

The metachromatic leukodystrophies (see Ta.bJe30.-6 ), also known as sulfatide lipidoses, are a group of lysosomal storage disorders recognized by the accumulation of excessive amounts of sulfatide. The term metachromatic, as a description of the diseases, derives from the staining properties of the stored lipid sulfatides, which develop a brown or gold hue with toluidine blue rather than the usual blue of myelin. The enzymatic defect involves arylsulfatase-A or cerebroside sulfatase-A. A...

Spinocerebellar Ataxia Type

The SCA1 locus in this autosomal dominant disorder was found on chromosome 6p in both Japanese and American families using serological markers of the human leukocyte antigen (HLA) system. In 1993, Orr and colleagues isolated the SCA1 gene and showed that the mutation was an unstable CAG trinucleotide repeat expansion within a translated region of the gene. '24 Although the repeat length in normals varies from 6 to 39 trinucleotides, SCA1 patients have one...

Reasoning and Problem Solving Through Concept Formation

Reasoning and problem solving are highly related to intellectual functioning. Similar to intellectual function, these abilities tend to be impaired following damage to the CNS. Specific location of injury appears to be less important to reasoning impairments, as does the presence of CNS disturbance. Impairments in reasoning and problem solving result in difficulties in all areas of daily functioning. Patients may be not be able to form generalizations from a given situation and interpret events...

Cognititve Function Assessed

Reasoning, problem solving, concept formation Reasoning, problem solving, concept formation Spatial reasoning Motor function Processing speed Construction Praxis sample of IQ scores (Verbal, Performance, and Full Scale) are a mean performance of 100, with a standard deviation of 15. In addition, individual subtest performance can be converted to standard scores with associated variability. Thus, the clinician is able to classify individual performance for both summary IQ measures and individual...

Distal Myopathies

The distal myopathies are a rare heterogeneous group of disorders characterized by progressive muscular weakness and atrophy beginning in the hands or feet ( . Table.36-7,). Several types of distal myopathies have been differentiated clinically, distinguished either by site of onset or mode of inheritance or by differences seen on muscle biopsy. The late adult-onset distal autosomal dominant myopathy that first appears in the hands, also called Welander distal myopathy or Swedish-type distal...

Disorders of Memory

A disorder of declarative memory is defined as amnesia. A pure amnesia refers to a relatively circumscribed disorder of declarative memory that cannot be accounted for by nonmnemonic deficits such as attention, perception, language, or motivation. Anterograde amnesia refers to the inability to acquire new declarative memories. Retrograde amnesia refers to the loss of memories acquired prior to the onset of the amnesia. Retrograde amnesias are described as flat when they extend back uniformly...

The Suprachiasmatic Nucleus

The anatomical structure serving as the internal circadian rhythm generator is the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. y , y Lesions of the SCN in rodents abolish circadian rhythmicity, and disconnection of the SCN from the rest of the brain also results in a loss of circadian rhythms in the brain in spite of continued fluctuations within the SCN. Furthermore, in animals with ablations of the SCN, transplantation of fetal SCN tissue restores circadian rhythm. Entrainment...

Location of Lesion Pattern of Weakness Reflexes and Associated Signs

Bilateral cerebral Tetraparesis, spastic dysarthria, dysphagia with hyperreactive jaw and facial jerks (pseudobulbar palsy), decorticate posturing (large Tetraparesis, coma, mid-size poorly reactive pupils, decerebrate posturing Locked-in syndrome tetraparesis, paralysis of horizontal eye movements, jaw, face, pharynx, and tongue muscles preservation of eye blink, vertical eye movements, consciousness Tetraparesis with or without weakness of pharynx and tongue Tetraparesis, no cranial nerve...

Pelizaeus Merzbacher Syndrome

Pelizaeus-Merzbacher syndrome occurs in a particular type of demyelinating sudanophilic leukodystrophy and has many subtypes. y In all, sudanophilia is produced when neutral fat stains such as Sudan black react with the neutral fat breakdown products of myelin. Since this breakdown of myelin is the result of a variety of metabolic or acquired insults, sudanophilia provides no useful information about the pathogenic origin of the insult. Most of the early reports were based on the pathological...

Third Order Neuron

The fibers of the medial lemniscus terminate in the ventroposterolateral (VPL) nucleus of the thalamus. This pathway is organized somatotopically such that the fibers from the nucleus gracilis end most laterally within the VPL nucleus and those from the nucleus cuneatus end in the larger, medial part of the VPL nucleus. The VPL nucleus is the origin of the third-order sensory afferent neuron that sends projections to somatosensory cortex (Fig. 19-1 (Figure Not Available) ). Primary...

Types of Detectable Abnormalities

In infants and very young children, brain structures can be visualized and congenital anomalies thereby detected. Differences in transduction by tissue, fluid, and blood permit a differentiation of hydrocephalus, cysts, and hemorrhage. Various tumors and vascular disorders, especially vascular malformations, can also be detected with US. In newborns up to 6 months of age, spinal cord lesions can also be detected with US because the posterior elements are membranous rather than bony. In adults,...

Clinical Environment

Asthma skin, kidney, encephalopathy, peripheral nerves Peripheral nerves and plexus, encephalopathy, palpable purpura Sinuses, respiratory tract, kidneys, cranial and peripheral nerves Peripheral nerves, muscle, eyes, lungs, skin, lymph nodes, brain granulomas Eyes, peripheral nerves, occasional strokes Syncope, light-headedness, headache, absent arm pulses (strokes rare) Aphthous oral ulcers, genital ulcers, eye inflammation, meningitis, brain stem lesions Interstitial keratitis of eye,...

T2Wl

Extracellular methemoglobin Cerebrospinal fluid Edema Neoplasms Abscess Demyelination Dysmyelination Acute to subacute infarcts Calcifications Deoxyhemoglobin Intracellular methemoglobin Hemosiderin Flow void in vessels Fat TABLE 23-5 -- MR SIGNAL CHANGE OF HEMORRHAGE TABLE 23-5 -- MR SIGNAL CHANGE OF HEMORRHAGE Extracellular Met-Hb and hemosiderin ring* *After slow reabsorption of the extracellular methemoglobin only decreased signal hemosiderin persists. *After slow reabsorption of the...

Syndromes of Overactivation

This movement disorder is characterized by unilateral, involuntary, episodic tonic and clonic contraction of muscles innervated by CN VII. It usually begins as twitches around the eye and progresses to involve the remaining ipsilateral facial muscles, even during sleep. The spasms are painless, can be provoked by voluntary facial motion and emotional stress, and occur most often in middle-aged women. The exact etiology is unknown, but many believe that compression of the motor nerve root at the...

Fabrys Disease

This X-linked lipidosis is characterized biochemically by the accumulation of two glycosphingolipids, globotriaosylceramide and galabiosylceramide. The enzymatic deficiency is alpha-galactosidase A. The molecular structure of the gene encoding the enzyme was first identified as the full-length cDNA clone and is localized to Xq21.33-q22.yi Twenty different mutations have been described for this gene and include deletions or duplications. The majority of the glycosphingolipids are synthesized in...

Clinical History

Clinical history is critical for speech and language assessment. Information from relatives, friends, or witnesses is often necessary owing to the patient's decreased ability to communicate. History taking should include the following components. Temporal development of symptoms provides valuable information on the underlying pathophysiogical process. An acute impairment of speech output indicates a possible underlying vascular, infectious, inflammatory, or traumatic pathology. A chronic and...

Acute Intoxication

In the nervous system, alcohol acts as a depressant, and small doses may lead to disinhibition or a slight euphoria. The toxic effects of alcohol become more prominent with rising blood levels, yet through repeated consumption, humans can become habituated rapidly. Although blood levels of 100 mg dl typically cause drunkenness in occasional imbibers, chronic alcohol abusers can tolerate levels up to 500 mg dl without any apparent effects. The toxic effects of alcohol can be produced in any...

Anatomy Of Praxis

Much of what we know about the anatomical basis of praxis (the ability to perform voluntary skilled movements) comes from the observations of patients with discrete cerebral lesions who have lost these abilities. To perform learned skilled movements, several types of knowledge are required. One must know how to move the limb through space (spatial trajectory) and how fast to move it. To successfully interact with the environment, a conceptual knowledge of praxis is also needed, such as what...

Historical Background

During the seventeenth and eighteenth centuries, physicians and morphologists (Wepfer, Willis, Morgagni, Cheyne, and others) recognized that the brains of patients who died of apoplexy often contained hemorrhages and softenings and that brain damage could result from either bleeding or deprivation of the vital blood supply. 1 , y During the nineteenth and early twentieth centuries, physicians became interested in correlating the neurological symptoms and signs found in stroke patients during...

Excessive Daytime Somnolence

EDS indicates the occurrence of abnormal sleepiness during the normal waking hours. y EDS may be associated with inadequate nocturnal sleep and can arise secondary to insomnia. EDS can also occur independently of insomnia. y Primary sleep disorders, such as sleep apnea and PLMD, may disrupt nocturnal sleep, leading to sleep deprivation and EDS. Often, patients with these disorders have frequent arousals punctuating the night but are unaware of these events. During the day, they report a...

Dermoid Epidermoid and Teratoma

These rare embryonic remnant tumors may present anywhere in the CNS but most commonly occur in the posterior fossa and the cauda equina. They are congenital tumors and may be seen at any age however, they are more likely to occur in children or young adults of either sex. They are slow growing and present with symptomatology specific for compressive syndromes at their location within the central nervous system. These symptoms can be insidious, and blockage of cerebrospinal flow occurs rarely....

Additional Neurological Findings

The presence of accompanying cortical signs other than memory loss helps to localize the anatomical basis of an amnestic syndrome. Accompanying dyspraxia, aphasia, or agnosia indicates that the cortex is involved in the pathological process. An assessment of affect is also important, since depression can produce a picture of seeming dementia (pseudodementia). Emotional lability or poor voluntary control over emotional expression (pseudobulbar affect) can occur in patients with...

Clinical Uses of Nerve Conduction Studies

Motor conduction studies are helpful in indicating that weakness is due to pathology of the peripheral nerves rather than other parts of the motor unit. Sensory conduction studies may indicate that sensory symptoms are due to an impairment of peripheral nerve function or, when normal, to a lesion proximal to the dorsal root ganglia. Motor and sensory conduction studies are important in determining the presence and extent of a peripheral neuropathy, distinguishing between a polyneuropathy and...

Alexias And Agraphias Languagerelated Disorders

Psychiatric disorders Right hemisphere disorders Dementing diseases lips and impairs enunciation of labial consonants (B, M, P). Neurological examination may reveal atrophy and fasciculations of the tongue and weakness of the palate and the facial muscles. When a history of variable dysarthria or dysphonia, with prominent fatigability is elicited, a neuromuscular junction disorder such as myasthenia gravis may be present. Spastic dysarthria is also called upper motor neuron dysarthria. It is a...

Visual Hallucinations

These are visual images that the patient claims to see but that other observers do not. Visual hallucinations can be characterized as unformed (e.g., dots, flashes, zig-zags) or formed (actual objects or people). They may occur in patients with damage to the afferent visual pathways, sensory deprivation, migraine, seizures, brain stem lesions, drug toxicity or abuse, and psychiatric illnesses. y Patients with visual loss due to a lesion anywhere within the afferent visual pathways may complain...

Sympathetic Innervation of the Pupil

In opposition to the pupillary constriction produced by cranial nerve III, the sympathetic system dilates the pupil. The dilator system functions by a reflex arc similar to the sphincter system. The afferent arm, however, is much less circumscribed than the light reflex. Afferent stimulation along pain and temperature pathways from the spinal cord generally causes pupillary dilatation that is abrupt in onset and lasts 20 to 60 seconds. More sustained dilatation often attends mental states...

Plexopathy

Sensory loss due to a lesion of the brachial plexus will appear in the distribution of two or more peripheral nerves if the lesion is infraclavicular and in the distribution of multiple cervical dermatomes if the lesion is supraclavicular. All sensory modalities may be involved. In radiation-induced plexopathy, 77 percent of patients have upper trunk involvement predominantly that generally occurs 3 months to 26 years after irradiation of the chest. It is quite characteristic to find myokymia...

Selected Nonatherosclerotic Occlusive Diseases

Fibromuscular dysplasia (FMD) is a rare condition that affects any or all of the three layers in the arterial walls of both extracranial and intracranial arteries, particularly those of the bilateral ICAs. FMD causes fibrous dysplastic tissue and proliferating smooth muscle cells in the media, presenting as constricting bands and a string-of-beads appearance on arteriography. '1 , y FMD is commonly found in middle-aged women and is most often asymptomatic. Because of its frequent association...

Basal Gangliar Interactions with the Cerebellum

Besides the basal ganglia, the cerebellum also has profound influences on motor function. Major cerebellar outflow paths converge on the ventral anterior and ventral lateral nuclei of the thalamus, and hence, these nuclei serve as a coordination center for the basal ganglia and cerebellar inputs to the cortex. Similar to the basal ganglia, the cerebellum influences the pyramidal system primarily through thalomocortical projections, and when cerebellar lesions occur, patients are poorly...

Category C Severely Symptomatic

Children who have any condition listed in the 1987 surveillance ease definition for acquired immunodeficiency syndrome (with the exception of LIP) Candidiasis, esophageal or pulmonary Mycobacterium, other species or unidentified species Mycobacterium avium complex or M. kansasii Pneumocystis carinii pneumonia Progressive multifocal leukoencephalopathy Salmonella Toxoplasmosis of the brain with onset > 1 month of age Wasting syndrome Adapted from centers for Disease Control and Prevention...

Table 162 Ototoxic Medications

Aspirin and sodium salicylate (cochleotoxic, reversible) Chemotherapy (mainly mixed toxicity) including lack of normal gesturing and spontaneous movements. The face is hypomimetic, with lack of expression, and there is reduced rate of blinking. Rest tremor, if present, is elicited when the hands and feet are completely relaxed. In hyperkinesias, key information is obtained by observing the patient at rest in complete repose without talking. Relaxing these patients and finding the best rest...

Growth Hormone Hypersecretion Museuloskeletal Increas

Ng hat, glove, or shoe sizes prognathism prominent supraorbital ridges coarsening of facial features (e.g, large bulbous nose, thick lips, separated teeth) Endocrine Hyperhidrosis, fatigue, exercise intolerance, hoarseness, sleep apnea (peripheral and central) Cardiopulmonary Hypertension, hyperlipidemia, cholelithiasis, carbohydrate intolerance, overt diabetes, heart disease (e.g., arrhythmias, congestive heart failure, coronary artery disease) Other Arthralgias, slight kyphosis,...