Christopher H. Comey

Radiation Optic Neuropathy after Stereotactic Radiosurgery

PURPOSE The purpose of the study is to report the occurrence of optic neuropathy after stereotactic radiosurgery for perichiasmal tumors. METHODS Records of four patients with visual deterioration after stereotactic radiosurgery were reviewed, including clinical findings, neuroimaging results, and treatment methods. RESULTS Optic neuropathy developed 7 to 30 months after gamma knife radiosurgery. All patients experienced an abrupt change in visual function. Clinical findings indicated anterior visual pathway involvement. Patterns of field loss included nerve fiber bundle and homonymous hemianopic defects. Gadolinium-enhanced magnetic resonance imaging (MRI) showed swelling and enhancement of the affected portion of the visual apparatus in three patients. Systemic corticosteroids were administered in all patients and one partially recovered. One patient also received hyperbaric oxygen without improvement. CONCLUSIONS Although rare, optic neuropathy may follow radiosurgery to lesions near the visual pathways. Careful dose planning guided by MRI with restriction of the maximal dose to the visual pathways to less than 8 Gy will likely reduce the incidence of this complication.

Management of Acute Odontoid Fractures with Single-screw Anterior Fixation

OBJECTIVE Accepted management strategies for odontoid fractures include external immobilization and surgical stabilization using anterior or posterior approaches. Displaced Type II fractures and rostral Type III fractures are at high risk for nonunion. Anterior fixation of odontoid fractures with a single cortical lag screw is a relatively new technique that combines rigid internal stabilization with preservation of intrinsic C1-C2 motion. We retrospectively reviewed our series of 26 consecutive patients who underwent odontoid screw fixation, to further define the safety and efficacy of the technique. METHODS During a 5-year period, 26 patients presented with acute traumatic Type II odontoid fractures. Ten patients were female and 16 were male, with a mean age of 35 years. All patients underwent anterior odontoid screw fixation by the senior surgeon (RWH), within a mean of 3 days after injury. All patients were postoperatively maintained in external orthoses, for a mean of 7.2 weeks, and were monitored with serial clinical and radiographic examinations. RESULTS With a mean follow-up period of 30 months, radiographic fusion was documented for 25 of 26 patients (96%). No complications related to the surgical approach were identified, and all patients remained in neurologically stable condition. Two complications (8%) were related to the instrumentation; one patient required external immobilization because of suboptimal screw placement, and one patient required posterior atlantoaxial arthrodesis because of inadequate fracture reduction. CONCLUSION Single-screw anterior odontoid fixation was associated with a relatively low complication rate and a high fusion rate in this study. We think that this should be the preferred treatment method for acute Type II odontoid fractures.

Pyogenic Spinal Epidural Abscess: A Minimally Invasive Technique for Multisegmental Decompression

Spontaneous spinal epidural abscess is a rare condition that is devastating and often fatal. Traditionally, surgery and antibiotics have been the treatment of choice; however, there has been some debate on the indications for their use. This technical note discusses a method for decompressing an acute multisegmental pyogenic spinal epidural abscess, thereby avoiding multilevel laminectomies.

Staged removal of acoustic tumors: techniques and lessons learned from a series of 83 patients.

The removal of large acoustic tumors is associated with increased mortality and cranial nerve injury. One method for treating these difficult lesions is staged resection. Between 1972 and 1992, more than 600 acoustic tumors were resected at our institution. Of these, 83 were removed in stages. This represents the largest series of staged acoustic tumor resections reported to date. A review of available films and patient records was performed for all acoustic tumors resected in stages between 1972 and early 1993 to analyze demographic information, tumor size, operative technique, outcome, and complications. The information was collected on standardized data sheets and entered into a computer database. Virtually all tumors were large, with the average size being 4 cm in greatest diameter. The average patient age was 41 years, and there was a slight preponderance of female patients. Ten patients had neurofibromatosis Type 2. The suboccipital approach was used in most patients. Anatomic preservation of the VIIth cranial nerve was achieved in > 72% of patients, with an average House-Brackmann score of Grade 3 at the longest follow-up (mean, 43 mo). Facial reanimation was performed in 19 of 23 patients with transected VIIth cranial nerves. Complications included cerebrospinal fluid fistulas in 11 patients, with 8 of 11 fistulas resolving after lumbar drainage. Six patients had meningitis (bacterial in three and aseptic in three). Two patients developed wound infections, and 10 patients developed exposure keratitis. There were two documented recurrences. There were no operative deaths. In most series, the incidence of cranial nerve deficits as well as morbidity and mortality is directly related to tumor size. Our operative strategy involved debulking the lateral aspect of large tumors during Stage I. Second stage removal is performed after the remaining tumor is shown to decompress out of the pons on computed tomographic or magnetic resonance images. During the second procedure, the residual tumor is less vascular and no longer densely adherent to the brain stem. Although staged removal is not without risk, there seems to be no apparent increase in morbidity when these results are compared with the results of series from the literature. Although there remain no absolute indications for staged resection of acoustic tumors, we think that it may represent the safest option for these difficult lesions.

Symptomatic tethering of the cerebellar vermis: case report.

A 25-year-old man with symptomatic tethering of the cerebellum is presented. At the age of 8 days, the patient underwent a limited repair of a posterior fossa encephalocele. He was well until the age of 24 when he began to experience paroxysms of extremity weakness, progressive incoordination, and pain at the base of the skull. Imaging demonstrated a connection between the cerebellar vermis and the subcutaneous tissue underlying the site of the previous encephalocele repair. Exploration of the area with the release of a fibrous stalk resulted in the rapid resolution of the patients symptoms.

Discogenic Lumbar Disease

The treatment of discogenic lumbar disease is a major challenge faced by physicians throughout the world. This condition affects many patients and will inevitably become more prevalent with a rapidly aging population. Disc degeneration tends to increase rapidly with age so that 10% of 50-year-old and 60% of 70-year-old discs are severely degenerated [1]. The current special issue explores several crucial angles related to the pathology, diagnosis, and treatment of discogenic lumbar disease.