Fractionated stereotactic radiotherapy for parasellar meningiomas: a preliminary report of visual outcomes.

BACKGROUND/AIM: Fractionated stereotactic radiotherapy (FSRT) is a new treatment for brain tumours that are close to critical structures, such as the visual apparatus. This study aims to assess the visual outcomes for patients with parasellar meningioma following FSRT. METHODS: A retrospective, non-comparative case series of 13 patients with parasellar meningiomas who were treated in one institution with FSRT between January 1995 and January 2001. RESULTS: 13 patients (26 eyes) were followed for a mean of 2 years. Visual acuity improved in four eyes (12.5%), remained stable in 18 eyes (75%), and worsened in three eyes (12.5%). Visual field improved in 15 eyes (57%), remained stable in six eyes (23%), and worsened in four eyes (15%). No adverse visual outcome occurred as a result of radiation. CONCLUSION: These preliminary findings suggest that FSRT is a safe and effective treatment for parasellar meningiomas.

Multifocal ERG in ethambutol associated visual loss.

AIM: To determine the anatomical site and extent of electrophysiological dysfunction in patients with ethambutol associated visual loss. METHODS: A comparative case series. Four patients with ethambutol associated visual loss underwent multifocal electroretinography (mERG). Two patients had advanced visual loss while two had early signs of toxicity. The N1-P1, N1, P1 amplitudes, N1, and P1 latencies were compared to 10 age and sex matched controls. RESULTS: mERG abnormalities were detected in the ethambutol treated patients. The N1 amplitude was significantly lower in the ethambutol treated patients than in the control group. CONCLUSION: Ethambutol is possibly toxic to the retina, and not only the optic nerve. The multifocal ERG may be of value to diagnose and monitor patients taking ethambutol.

Identification of gonadotroph adenomas in men with clinically nonfunctioning adenomas by the luteinizing hormone beta subunit response to thyrotropin-releasing hormone.

Because of the recent finding that a majority of clinically nonfunctioning pituitary macroadenomas in women could be identified as of gonadotroph origin by their LH beta-subunit responses to TRH, we evaluated in this study the value of the LH beta-subunit response to TRH in identifying gonadotroph adenomas in men with clinically nonfunctioning macroadenomas. Thirty-eight consecutively studied men with clinically nonfunctioning macroadenomas were given TRH iv, and intact FSH and LH and LH beta- and alpha-subunits were measured every 15 min for 90 min before and 90 min after. TRH tests were also performed on 15 healthy, age-matched control men and on 12 men with adenomas secreting GH or PRL. Of the 38 men with clinically nonfunctioning macroadenomas, basal values were supranormal in 10 for FSH and in 6 each for alpha- and LH beta-subunits. Responses to TRH were elevated, compared to the healthy, age-matched controls, in 14 for LH beta-subunit and in 5 each for intact FSH and LH. None of the men with adenomas secreting GH or PRL exhibited supranormal responses to TRH. Of the 38 clinically nonfunctioning adenomas, 35 were established in dispersed cell culture, and 29 secreted readily detectable amounts of intact FSH, LH, and LH beta-subunit, strongly suggesting that these adenomas were of gonadotroph cell origin. We conclude that the LH beta-subunit response to TRH can identify gonadotroph adenomas in men with clinically nonfunctioning adenomas better than can basal concentrations of intact FSH and alpha-subunit, alone or combined, but not as well as it can in women.

Follicle-stimulating hormone-secreting pituitary adenomas: correlation of reduction of adenoma size with reduction of hormonal hypersecretion after transsphenoidal surgery.

Ten men who had FSH-secreting pituitary adenomas were evaluated before and 4-6 weeks after transsphenoidal surgery to determine whether reduction of adenoma mass would ameliorate the hormonal abnormalities associated with these adenomas. Nine of the 10 men exhibited marked reduction in adenoma size, as judged by computerized tomography, an 7 had improvement in vision. The same 9 men also had decreases in basal serum FSH concentrations to within the normal range after surgery. The 1 man who had no reduction in adenoma size by computed tomographic scan and whose serum FSH concentration did not decrease to normal after surgery was also the only patient whose abnormal FSH and LH responses to TRH did not improve after surgery. Another man, who had a reduction in adenoma size and serum FSH concentration after surgery, subsequently had regrowth of the adenoma and concomitant resurgence of the FSH concentration. Two men had increases in their serum testosterone concentrations from subnormal to well within the normal range after surgery, suggesting that gonadotroph cell adenomas may impair LH secretion from normal gonadotroph cells. We conclude that the correlation of reduction in adenoma size with reduction in hormonal hypersecretion after surgery suggests that the hormonal hypersecretion is a direct consequence of the adenomatous tissue.

Inhibition of follicle-stimulating hormone secretion from gonadotroph adenomas by repetitive administration of a gonadotropin-releasing hormone antagonist.

As a preliminary step in searching for a pharmacological treatment for gonadotroph adenomas, we administered the GnRH antagonist analog Nal-Glu GnRH to five patients, four men and a woman, with FSH-secreting gonadotroph adenomas in order to determine its effect on FSH secretion. Administration of a single 10-mg dose of Nal-Glu GnRH to four of the patients produced a significant decrease in the serum FSH concentration in two patients and returned the FSH level to normal in only one. Administration of 5 mg Nal-Glu every 12 h for 7 days, however, produced a significant (P less than 0.001) decrease, and to within the normal range, in four of the five patients (mean +/- SEM, 32.7 +/- 5.6 IU/L during the 3 days before treatment and 9.8 +/- 1.4 IU/L during the last 3 days of treatment). Also, in response to the 7-day treatment, LH fell significantly in all five patients, alpha-subunit fell in three, and testosterone fell in all four men. Administration for 6 weeks of the GnRH agonist analog leuprolide did not decrease the serum FSH concentration of one of the patients whose serum FSH did decrease in response to Nal-Glu GnRH. We conclude that repetitive administration of Nal-Glu GnRH may often inhibit FSH secretion by gonadotroph adenomas and that FSH secretion by gonadotroph adenomas may be dependent on endogenous GnRH secretion.

Primary aberrant aculomotor regeneration. A sign of intracavernous meningioma.

Four patients exhibiting signs of partial aberrant oculomotor regeneration without a preceding acute third nerve palsy had meningiomas involving the cavernous sinus. Two of the patients had preceding sixth nerve palsies. We propose that slowly progressive primary aberrant oculomotor regeneration is diagnostic of intracavernous meningioma. The best diagnostic studies are orbital phlebography, carotid arteriography, and possibly computerized axial tomography.

Cavitary developmental defects of the optic disc. Visual loss associated with optic pits and colobomas.

Congenital cavitary anomalies of the optic disc (optic pit and coloboma) are uncommon and frequently go unrecognized. Patients with these defects have a high incidence of visual loss and the abnormal appearance of the discs may be mistaken for atrophy due to acquired neurological disease. Occasionally, associated midline neurological developmental malformations will be found associated with pits, colobomas, or other dysplastic optic discs, as in one of our cases. A group of patients with optic pits and colobomas referred for neurological evaluation of visual loss are presented to remind the neurologist of the appearance of these congenital crater-like defects and of the causes of loss of vision.

Visual evoked potentials in occipital lobe lesions.

Recording of visual evoked potentials (VEPs) to pattern reversal is considered to be a reliable diagnostic procedure for examining patients with anterior visual pathway lesions (optic nerves and chiasm). Less consistent results have been reported in studies of more posterior lesions. The VEPs were recorded in 20 patients with occipital lobe lesions. A maximal VEP response (P94) was recorded at the scalp electrodes situated over the involved occipital lobes and contralateral to the hemianoptic visual field defect, indicating a positive correlation of unilateral occipital lobe lesions, homonymous visual field loss, and the VEP abnormality.

Abnormal ocular pneumoplethysmographic results in unilateral neovascular glaucoma.

Little is known about the predictive value of ocular pneumoplethysmography in patients with ophthalmic disease. We evaluated eight patients with unilateral increased intraocular pressure due to neovascular glaucoma who did not have evidence of severe extracranial carotid stenosis by duplex scanning and continuous-wave Doppler ultrasound. The ophthalmic systolic pressure measured by ocular pneumoplethysmography was decreased in the affected eye of all eight patients, indicating that neovascular glaucoma may be a cause of abnormal ocular pneumoplethysmographic results. Patients with neovascular glaucoma tended to have larger interocular ophthalmic systolic pressure differences than other patients with false-positive ocular pneumoplethysmographic results by noninvasive criteria.

Visual loss in pseudotumor cerebri. Follow-up of 57 patients from five to 41 years and a profile of 14 patients with permanent severe visual loss.

The prognosis for vision in most patients with pseudotumor cerebri is excellent; however, visual loss, which is the only serious complication, may occur either early or late in the course of the disease. A group of 57 patients was followed up five to 41 years with visual fields, visual acuity, and fundus photographs. Blinding visual loss or severe visual impairment in one or both eyes occurred in 14 patients, and in seven patients, this occurred months to years after the initial symptoms. Systemic hypertension was a significant risk factor for visual loss in patients with pseudotumor cerebri, and blindness occurred in eight of 13 patients who were hypertensive. Despite suggestions that blind spot measurement is useful for following up patients with this condition, we believe that sequential quantitative perimetry gives more complete information and is essential to rational decision making in the treatment of pseudotumor cerebri.

Traumatic chiasmal syndrome.

We studied 11 patients with the uncommon finding of traumatic chiasmal syndrome after closed head trauma. Visual field defects varied from complete monocular blindness and contralateral temporal hemianopia to subtle bitemporal arcuate scotomas. The degree of visual loss was not necessarily related to the severity of the craniocerebral trauma. Diabetes insipidus was present in half of these patients, but unlike the visual abnormalities, this complication was transient.

Factors influencing outcome of prednisone dose reduction in myasthenia gravis.

We reviewed retrospectively 114 prednisone dose reduction attempts in 63 myasthenic patients. Dose reduction was considered successful if a patient remained asymptomatic for more than 1 year on no prednisone or a stable low dose of prednisone. Successful dose reduction attempts were more common in patients taking azathioprine, but thymectomy did not influence taper outcome. Slower rate of dose reduction and higher ending dose of prednisone improved the chance of success.

Positron emission tomography in a patient with progressive multifocal leukoencephalopathy.

A 56-year-old man with chronic lymphocytic leukemia, progressive multifocal leukoencephalopathy, and a dense left homonymous hemianopia had 18F-fluorodeoxyglucose positron emission tomography. Cortical glucose metabolism was decreased in the right cerebral hemisphere and the left cerebellar hemisphere. To our knowledge, this is the first demonstration of cerebral and cerebellar hypometabolism due solely to white matter disease.

Comparison of metrizamide computed tomography and magnetic resonance imaging in the evaluation of lesions at the cervicomedullary junction.

We compared intrathecal metrizamide-enhanced CT (metrizamide-CT) and magnetic resonance imaging (MRI) in the evaluation of 17 patients with clinical suspicion of lesions at the cervicomedullary junction. MRI was superior in imaging the position of the cerebellar tonsils and the size and extent of mass lesions. MRI and metrizamide-CT were equal in detecting syringomyelia. CT with and without IV contrast enhancement was necessary to detect calcium or defects in the blood-brain barrier within neoplasms.

Ischemic lesions of the occipital cortex and optic radiations: positron emission tomography.

We used 18-F-fluoro-2-deoxyglucose positron emission tomography (PET) and computed tomography (CT) to study eight patients with homonymous hemianopias or quadrantanopias due to ischemic lesions of the visual pathways. Four patients with ischemic damage to all or part of the occipital lobe had decreased glucose metabolism in the affected region. Three patients with ischemic damage limited to the optic radiations had decreased glucose metabolism in the portion of striate cortex appropriate for the visual field defect. Changes in glucose metabolism frequently occurred in the undamaged ipsilateral thalamus and visual association areas.

Blink-saccade synkinesis.

We studied two patients who could make saccades of normal velocity and amplitude only in association with a simultaneous blink. In one patient, the initiation of saccades was also facilitated by blinks. Both patients had signs of cerebellar or brainstem dysfunction, suggesting a posterior fossa localization for blink facilitation of saccadic velocity and amplitude.

Radiologic evaluation of the mediastinum in myasthenia gravis.

We reviewed the records of 36 patients with myasthenia gravis who had CT of the anterior mediastinum before thymectomy in an effort to improve preoperative detection of thymoma. At surgery, 10 patients had thymomas, 21 had germinal center follicular hyperplasia, and 5 had histologically normal glands. CT performed on an EMI 5005 was abnormal in 23 of 36 patients; 10 had thymoma, 11 had hyperplasia, 1 had a normal gland, and 1 had a cyst. Tumors were detected by routine chest x-ray in 5 of 10 patients and by linear tomography in 7 of 8. All four patients with calcified masses on CT had thymomas (including the patient with normal linear tomograms). CT alone is too sensitive a screening test; 12 of 25 patients with hyperplasia or normal glands had abnormal scans. However, in combination with chest x-ray and linear tomography, we detected 10 of 10 patients with thymoma with reasonable certainty.

Melioidosis and bilateral third-nerve palsies.

Central nervous system involvement in melioidosis is unusual. We describe a 34-year-old man who developed a Pseudomonas pseudomallei meningitis, manifested as bilateral third-nerve palsies, 13 years after having been in southeast Asia. Diagnosis was established by a fourfold rise in the serum antibody titer for the bacterium. Recovery occurred after treatment with rifampin, isoniazid hydrochloride, ethambutol, and trimethoprim-sulfamethoxazole. Since a long latent period from exposure to overt infection is possible, additional cases of melioidosis in the United States can still be expected in veterans of the Vietnam War.

Atherosclerotic carotid artery disease in patients with retinal ischemic syndromes.

The extracranial carotid systems of 105 patients with retinal ischemia were examined using B-mode ultrasonography with integrated pulsed Doppler. Sixty-four patients had amaurosis fugax (AF), 17 central retinal artery occlusions (CRAO), and 21 branch retinal artery occlusions (BRAO). The prevalence of carotid stenosis (greater than or equal to 60%) ipsilateral to the symptomatic eye was low (16%). Eighty-six percent of AF patients had either no plaque causing less than a 60% stenosis. A significant proportion of subjects with normal duplex scans had alternative explanations for their retinal ischemia (eg, migraine, cardiac embolus). Patients with Hollenhorst plaques were more likely to have stenotic or ulcerated plaque (p = 0.04). The degree of carotid stenosis correlated significantly with the number of vascular risk factors identified in individual patients (p = 0.02). The presence of risk factors was more common in CRAO and BRAO patients compared with the AF group. Combined ultrasound-Doppler investigations of the carotid bifurcation are valuable noninvasive tools for the screening of patients with retinal ischemia.

Hypopituitarism following radiation therapy of pituitary adenomas.

Pituitary function was evaluated before and after supervoltage radiotherapy for a pituitary adenoma in 35 patients; 22 had had prior surgical treatment, and 13 had not. For comparison, pituitary function was also followed concurrently in another 10 patients whose pituitary adenomas were treated surgically, but who did not receive subsequent radiotherapy. Following radiotherapy, deficiencies of adrenal, thyroid, and gonadal function developed in 67, 55, and 67 percent of the patients who had previously been treated surgically during a mean of 4.2 years of observation, and in 55, 15, and 50 percent of the patients who did not have prior surgery during the subsequent five years. In contrast, in patients who had previously been treated surgically and who did not receive radiation, deficiencies of these hormones developed in only 13, 13, and 0 percent during four years of observation. It is concluded that supervoltage radiotherapy for pituitary adenoma, especially when preceded by surgical treatment, frequently produces, during the ensuing four to five years, deficiencies of pituitary hormones that had been secreted normally prior to irradiation.