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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.

A case of epidermoid tumor enveloping an aneurysm of the anterior communicating artery is reported. Four embryologically similar epithelial tumors of the central nervous system associated with intracranial aneurysms, all craniopharyngiomas, have previously been reported. Theories attempting to relate tumor and aneurysm are discussed. The incidence of aneurysm associated with tumor is difficult to estimate and may be no greater than the probability of their coincidence by chance alone.

Forty female patients with pituitary adenomas were studied retrospectively to determine whether factors could be identified that would help predict outcome from operation. Twenty-five patients had a normal prolactin level (less than or equal to 30 ng/ml) during the early postoperative period (less than or equal to 3 months) and 15 patients had persistent disease (prolactin greater than 30 ng/ml). Nine of the 25 patients who initially had normal prolactin levels during the early postoperative period were found to have elevated prolactin levels during the late postoperative period (greater than 3 months). As has been shown previously, tumor size and preoperative prolactin levels were important factors in predicting surgical outcome. Patients with smaller (Hardy Grades I and II) tumors had significantly better outcome than those with larger (Hardy Grades III and IV) tumors. Patients with successful surgical outcomes had significantly lower preoperative prolactin values (204 ng/ml) than those with operative failures (524 ng/ml). In addition to the known factors, the patient's age at the time of operation, the length of amenorrhea, and the patient's growth hormone response to insulin hypoglycemia were newly identified as factors that helped predict surgical outcome. Patients who were less than or equal to 26 years of age and who had had amenorrhea for less than or equal to 6 years at the time of operation had significantly better surgical outcomes. Patients with normal growth hormone responses to stimulation testing had significantly better surgical outcomes than those with a blunted preoperative growth hormone response. The data suggest that prolactin-secreting pituitary tumors may cause a progressive disorder for which operative cure may be obtained only early in the disease.

I-cell disease (ICD), mucolipidosis II, is an autosomal recessive syndrome resulting from defective phosphorylation of acid hydrolases. The diagnosis is made in early childhood and in most cases death occurs by age 5 as a result of cardiorespiratory complications. Pathologic changes are limited to mesenchymal tissues. We treated two children with ICD who developed atlantoaxial dislocation and myelopathy following minor injuries. The first child developed cardiovascular instability with manipulation of the C1 ring at operation, necessitating removal of the arch of C1 and fusion from occiput to C2. The second child was quadriplegic following anatomic reduction of the C1–C2 dislocation at operation during which somatosensory evoked potentials (SSEPs) showed no deleterious change. The atlantoaxial joint is unstable in ICD due to an incompetent transverse ligament infiltrated by storage cells. A cartilaginous, rather than calcified, odontoid process may contribute to the instability. The intraoperative neural injury occurred during attempts to effect anatomical reduction of the chronically dislocated C1–C2 joints and could have resulted from inadvertent trauma to the vertebral arteries and subsequent infarction of the cord. The lack of change in the intraoperative SSEPs was probably due to relative sparing of the posterior columns during the cord injury. We recommend that children with ICD and atlantoaxial instability undergo closed reduction of any existing malalignment followed by posterior C1–C2 fusion as long as the operative risk is not prohibitive. If preopera-tive closed reduction is not readily feasible and the cord is severely compromised, the C1 arch should be removed and the occiput fused to C2. Forceful attempts at anatomical reduction of the chronically dislocated C1–C2 segments should be avoided.

Large pituitary tumors are still a common problem. Thirty consecutive patients underwent operative decompression and radiation therapy for large sellar and suprasellar tumors. They were studied prospectively in terms of their endocrine outcome. Ten of the patients had panhypopituitarism both before and after treatment. The other 20 patients had partial hormonal deficits prior to treatment. Ten (50%) of the 20 patients who had partial preoperative deficits went on to develop delayed onset of worsening in their endocrine function; 9 of the 10 developed panhypopituitarism, and 1 patient developed decreased thyroid function. The mean time from surgery until the onset of delayed worsening in endocrine function was 26.1 months. The mean age of those patients who developed delayed onset of worsening in pituitary function was significantly higher than that of those who did not develop further hormonal loss (40.5 ± 3.1 years versus 52.0 ± 4.1 years, P < 0.05). None of the 10 patients with delayed onset of worsening in pituitary function had anatomical evidence by computed tomographic scan of tumor recurrence. Delayed onset radiation effect is the most likely cause of the late onset of worsening in endocrine function.

We report a case of brain abscess complicating the use of a halo orthosis in the treatment of a cervical spine injury suffered during wrestling. Four previous brain abscesses complicating the use of halo orthoses have been reported. All cases of abscess have been associated with overlying infection at the site of pin insertion. Our case and at least one of those previously reported may have been related to tightening of the halo pins after placement. Serious spine injuries occur rarely in wrestlers and are associated with the use of illegal holds and maneuvers in which one athlete is thrown to the mat. The pathophysiology and radiographic appearance of a unilateral facet dislocation are reviewed.

Aspergillus species are second only to Cryptococcus neoformans as the most common cause of fungal infections of the central nervous system in immunocompromised patients. Survival following treatment of Aspergillus brain abscess has been reported only 4 times. In each case, craniotomy was performed for abscess drainage. We present a case of long-term survival following stereotactic drainage of a bilateral Aspergillus brain abscess. In all reported cases, including the present one, histological examination of the abscess contents established the correct diagnosis. Amphotericin B was used in combination with operation in 4 of the 5 cases of long-term survival.

✓ In an effort to reduce the incidence of postoperative wound infection, the recently proposed regimen of intravenous vancomycin and tobramycin and streptomycin irrigating solution was used in 878 neurosurgical operations. There were eight infections, for an infection rate of 0.9%. This infection rate was compared to the rate in the previously reported series using a sequential statistical analysis. The infection rate was found to be signficantly greater than that previously reported. Controlled clinical trials will be required before the efficacy of antibiotic prophylaxis in clean neurosurgical procedures can be considered proven.