Removal of Hamartomas

Intramedullary dermoid cysts are growing lesions due to the metabolic activity of the cells in the cyst wall. These do not proliferate, but continue to produce substances that fill the cyst causing its expansion. Thus, radical excision of the entire cyst and its wall is the goal of surgery. Otherwise, a recurrence is almost certain. Unfortunately, this may be extremely difficult to achieve. The cyst wall may be extremely adherent to the spinal cord tissue requiring sharp dissection to deliver the cyst wall. If the cyst contents spill into the subarachnoid space during surgery, aseptic meningitis may result. If the cyst had ruptured prior to surgery, severe arachnoid adhesions may have formed (Fig. 3.50) [65] or the cyst contents may gradually spread inside the expanded central canal in a cranial direction [170]. Even abscess formations have been described [49]. Complete removal of a dermoid cyst may be impossible without damaging the cord in such instances. Partial resections or cyst evacuations are sometimes all that can be done (Fig. 3.50).

The intramedullary part of a spinal lipoma does not display a cleavage plane toward the spinal cord tissue. Therefore, attempts ofradical resection are not recommended. As the lipoma does not display proliferative potential, decompression is all that is required. This may involve a partial resection of the extramed-ullary component in some cases. Usually, we just perform a laminotomy with a duraplasty (Fig. 3.51). As lipomas may be associated with arachnoid scarring [73, 171, 281] we prefer to leave the arachnoid membrane intact if no debulking is required.

Surgery for an intramedullary hamartoma may have to involve more than removal or decompression. Additional tethering mechanisms such as a diastema-tomyelia or a thick filum terminale may also have to be addressed. These techniques are described in the section on extramedullary tumors.

Fig. 3.50. T1-weighted, contrast-enhanced sagittal (a) and axial (b) MRI images of a recurrent intramedullary dermoid cyst at Th11-L1 in a 31-year-old woman with a 9-month history of pain and a slight paraparesis with intact sphincter functions. c This intraoperative view at dura opening shows the underlying adhesions between the dura, arachnoid membrane, and cord. The dermoid cyst is completely intramedul-

Fig. 3.50. T1-weighted, contrast-enhanced sagittal (a) and axial (b) MRI images of a recurrent intramedullary dermoid cyst at Th11-L1 in a 31-year-old woman with a 9-month history of pain and a slight paraparesis with intact sphincter functions. c This intraoperative view at dura opening shows the underlying adhesions between the dura, arachnoid membrane, and cord. The dermoid cyst is completely intramedul-

lary at this level. d At the lower pole, arachnoid adhesions with the capsule of the exophytic dermoid cyst are visible. After partial resection, the upper (e) and lower (f) sections of the tumor bed reveal the amount of decompression. It was judged too hazardous to dissect the densely adherent capsule out of the cord. (Continuation see next page)

Fig. 3.50. (Continued) g The durawas closedwith afascia lata duraplasty. Postoperatively, the patient has been free of a recurrence for 4 years with an unchanged neurological status, improved pain, but distressing dysesthesias

Chest Wall Lipoma Removal
Fig. 3.51. T1-weighted sagittal (a) and axial (b) MRI images of an intramedullary lipoma at C7-Th1 in a 42-year-old woman with a 4-year history of severe pain and a moderate parapa

resis. She had undergone a previous operation elsewhere with-outbeneficial effect. (Continuation see next page)

Epidural Tumor Resection
Fig. 3.51. (Continued) There is no major space-occupying effect detectable from this lipoma. c, d Intraoperative views after dura opening displayed a partly exophytic lipoma covered by posterior roots. After arachnoid dissection to untether the cord, no further attempts to remove the lipoma were un

dertaken. The dura was closed with a fascia lata duraplasty to avoid retethering. The post-operative sagittal T1- (e) and T2-weighted (f) images reveal no major cord tethering 3 months after surgery. Neurological symptoms gradually improved with a marked relief of pain

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