Chiasmal syndrome in sarcoidosis

Cranial neuropathies in sarcoidosis

Sarcoidosis is a multisystem, chronic inflammatory disease that is characterized by the development of non-caseating granulomas in multiple body tissues and organ systems. Neurological complications of systemic sarcoidosis include peripheral and cranial neuropathies, myopathies, seizures, gait dysfunction, and cognitive decline. Because sarcoidosis has a predilection to involve the basilar meninges, cranial neuropathy is the most prevalent neurological deficit seen when the nervous system is involved. Sarcoidosis cranial neuropathy may occur at different stages of the disease and even as the initial clinical manifestation of central nervous system involvement. Attributing a cranial neuropathy to sarcoidosis can be challenging, particularly in the setting of normal imaging studies. In this review, cranial neuropathies in sarcoidosis are discussed in detail.

Non-compressive disorders of the chiasm

Chiasmal dysfunction produces a characteristic clinical picture, regardless of the mechanism. In most cases a compressive lesion is the cause. In occasional cases, however, no such extrinsic mass is found and other possible etiologies must be explored. In some of these cases, the pathologic process is identifiable with appropriate neuroimaging. For example, inflammation, infiltrative tumors, and radiation necrosis produce intrinsic chiasmal enhancement. Chiasmal ischemia may require specialized magnetic resonance (MR) sequences for diagnosis. Chiasmal hemorrhage, trauma and chiasmal herniation typically produce distinctive changes on noncontrasted imaging. In cases of metabolic insult, either toxic or hereditary, radiographic changes are typically absent. In each of these, the correct diagnosis can usually be made with a combination of clinical and radiographic features.

Nonuniform pressure generation in the optic chiasm may explain bitemporal hemianopsia

PURPOSE

To measure the pressure in the temporal and central aspects of the chiasm simultaneously during compression of the optic chiasm from below with an expanding simulated tumor.

DESIGN

Experimental study.

METHODS

Craniotomies were performed on 5 unfixed cadaveric specimens ranging in age from 49 to 89 years, and the optic chiasm was exposed. After a pediatric gauge Foley catheter was inserted into the sellar region, the temporal side of the chiasm (temporal aspect uncrossed fibers) was impaled with a 30-gauge needle connected to a pressure transducer. In like fashion, the central portion of the chiasm (crossed fibers) was impaled with another 30-gauge needle connected to a pressure transducer on a separate channel. The Foley catheter was inflated for a period of 30 seconds to 1 minute and the pressure in each channel continuously monitored. Multiple trials were performed on each of the 5 specimens.

MAIN OUTCOME MEASURE

Pressure change between the temporal and nasal aspects of the optic chiasm.

RESULTS

In all cases in which intrachiasmal pressure could be measured, higher pressures were always generated in the central aspect of the chiasm than in the temporal aspect of the chiasm. In cadaver 1, the mean central pressure was 19.75 mmHg, whereas the mean temporal pressure was 6 mmHg. In cadaver 5, the mean central pressure was 4 mmHg, whereas the mean temporal pressure was zero. Donors 70 and older demonstrated abnormally thin and frail chiasms that were unable to support a sustained pressure increase during simulated tumor expansion.

CONCLUSIONS

During deformation of the optic chiasm from below by a radially expanding mass analogous to a pituitary tumor, the central aspect of the optic chiasm consistently manifests a higher pressure than the temporal aspect. It is hypothesized that the peculiar geometry of the optic chiasm renders the crossing nasal fibers more prone to a deformation stress exerted from below. Nonuniform pressure generation between the central and temporal aspects of the chiasm results in a greater effective stress on the crossing fibers of the chiasm and may be responsible for the clinical phenomenon of bitemporal hemianopsia.

Neurosarcoïdose : état des connaissances

The origins of neurosarcoidosis, a multisystemic granulomatous disease, remain unknown. Nervous system localizations remain rare, but severe. Lymphocytic meningitis, psychiatric disorders, diabetes insipidus and cranial nerve palsy are the most frequent signs. Cerebral fluid test and cervical medullar and cerebral MRI with gadolinium have to be performed first. In some cases, histological evidence of granuloma have to be obtained with neuromuscular, meningeal or cerebral biopsies. Functional impairment and life-threatening conditions require early corticosteroid therapy. In worsening cases or in the event of no therapeutic response or poor tolerance to corticosteroids, other immunosuppressive agents should be associated. Maintenance therapy and most often life long maintenance therapy allow a continuous success while avoiding relapse.

Optic nerve enlargement and chronic visual loss

We present four patients with sarcoidosis of the anterior visual pathways. The first patient presented with unilateral visual loss, a mass lesion at the optic nerve head, and an enlarged orbital optic nerve. The second patient presented with bilateral progressive painless visual loss, associated with optic nerve pallor and visual field loss. In these two patients, optic nerve biopsy was diagnostic of sarcoidosis. The third patient developed optic nerve and chiasmal involvement after sarcoidosis was established by lacrimal gland biopsy. The fourth patient had optic nerve, pulmonary, and lymph node involvement with sarcoidosis. A conjunctival and lung biopsy were diagnostic. Computed tomography and magnetic resonance imaging have greatly facilitated diagnosis of sarcoidosis of the anterior visual pathways. Sarcoidosis of the anterior visual pathways may occur alone or in association with other ocular or systemic manifestations. A conjunctival or lacrimal gland biopsy may be preferable as the initial diagnostic approach. Treatment of patients with this condition may require systemic immunosuppression, in addition to corticosteroids, to prevent permanent visual loss.

Low-dose cyclosporine therapy of granulomatous optic neuropathy and orbitopathy

Four patients with granulomatous disease of the anterior visual pathway presented with optic neuropathy between July 1986 and February 1987, secondary to an orbital pseudotumor (n = 1) and sarcoidosis (n = 3). All but one became resistant to corticosteroid therapy, and all were subsequently treated for 1 to 2 years with low-dose cyclosporine alone or in combination with tapering doses of prednisone. Two patients experienced pronounced recovery of visual function, and visual function was stabilized in the other two; in one of these, magnetic resonance imaging showed substantial regression of intracranial lesions. Steroid-induced complications of uncontrolled hyperglycemia (n = 2) and obesity (n = 4) were controlled with cyclosporine. The authors conclude that low-dose cyclosporine is a safe and effective therapeutic alternative in ocular granulomatous diseases.

The perils of Pauline: visual loss in a tippler

A 31-year-old alcoholic woman who smoked had subacute visual loss. She was treated for tobacco-alcohol amblyopia with subsequent improvement in vision.

Pituitary sarcoidosis

A 66-year-old woman presenting with pituitary insufficiency was operated on for an intrasellar tumor. Surprisingly, this tumor, at first suspected to be a hormone-inactive pituitary adenoma, consisted in fact of sarcoid granulomatous tissue in the pituitary gland as found histologically. The morphological picture as seen in the cranial computed tomography was identical with that of an adenoma. This possibility had not previously been considered, although there had been an extracerebral manifestation of the sarcoidosis in the left ovary.

Sarcoidosis of the anterior visual pathway: successes and failures

Four patients with progressive visual deterioration were found to have sarcoidosis involving the anterior visual pathway. They all developed chiasmal dysfunction and bilateral optic neuropathy, which responded to megadose corticosteroid therapy. When an attempt was made to withdraw the corticosteroids, the patients experienced a recrudescence of visual dysfunction and were subsequently unable to tolerate the corticosteroid dose levels necessary to maximise their visual potential. Each patient was treated with high-voltage radiation therapy, totalling up to 4500 rads. The beneficial response obtained was temporary, and immunosuppressive therapy with azathioprine or chlorambucil was instituted, preventing further deterioration.

Progressive visual loss with normal examination. A conundrum

A 68-year-old woman experienced rapid progressive visual loss to blindness over a seven-week period. Inadequate clinical and diagnostic testing masked the diagnosis of a malignant glioma of adulthood.

Combined clinical and computed tomographic diagnosis of orbital glioma and meningioma

The clinical information on 22 patients with orbital optic nerve gliomas and 47 patients with meningiomas was correlated with computed tomographic findings obtained in both axial and coronal studies. Most of the gliomas occurred in children, although 7 patients presented after 20 years of age. Among the patients with meningiomas, the majority were women in early middle age, although two tumors occurred in children less than 20 years of age. Low grades of proptosis (median, 2 mm for both tumors), frequent significant visual field obscurations with eye movements, and opto-ciliary shunt vessels pointed toward the diagnosis of an optic nerve tumor. Patients with gliomas generally manifested massively swollen fusiform optic nerves with clear-cut margins due to circumscription by an intact dura. Kinks and bucklings of the optic nerve as well as infarctive cysts distinguished the glioma CT-scan patterns from the meningiomas. Distinctive axial CT-scan features of the meningiomas not shared by the gliomas were narrowly and diffusely enlarged nerves with polar expansions either at the orbital apex or immediately behind the globe; calcification; irregular excrescent margins signifying extradural invasion into the orbital soft tissues; a negative optic nerve shadow running down the center of the lesion; and bone erosion near the orbital apex. Coronal studies often revealed irregular margins signifying transgression of the dura. A diffusely and narrowly enlarged optic nerve shadow with regular margins (intrasheath lesions) was the one morphologically overlapping pattern displayed by 11 meningiomas and three gliomas. In these cases there tended to be more profound visual loss in the gliomas compared with the meningiomas, as well as the more frequent presence of opto-ciliary vessels in the meningiomas. Arteriography may be helpful in this particular category by demonstrating a tumor blush for the meningiomas, whereas this finding is typically absent with optic nerve gliomas. Meningiomas may be very closely simulated by dural or intraneural inflammations.

Eleven cases of sarcoidosis of the optic nerve

Of 11 patients (eight women and three men, ranging in age from 16 to 48 years) who had sarcoidosis of the optic nerve that caused decreased visual acuity and visual field abnormalities, only two were known to have sarcoidosis at the time the visual impairment developed. Four patients had granulomas involving the optic nerve head, four had granulomatous inflammation of the orbital or intracranial optic nerve or chiasm, and three had retrobulbar neuritis. All 11 patients had histologically confirmed idiopathic noncaseating granulomatous inflammation and eight of the 11 had abnormalities compatible with sarcoidosis in chest roentgenograms. In the three patients in whom the serum level of angiotensin-converting enzyme was determined, it was increased in one and normal in the other two. Computed tomography of the anterior visual pathways was the single most useful neurodiagnostic study. Treatment with corticosteroids was beneficial in six of the 11 cases. These cases demonstrated that sarcoidosis should be included in the differential diagnosis of any inflammatory or compressive lesion involving the anterior visual pathways.