INTRODUCTION Granulomatous inflammation is a distinctive ...

sequentially in approximately one third of patients (Oksanen, 1986). In isolated facial nerve palsy
secondary to sarcoidosis, the CSF is usually normal; however, when associated with other
neurological manifestations, the CSF can be abnormal in up to 80% of cases. The site of facial
nerve involvement in neurosarcoidosis is unclear. Facial neuropathy often is associated with
dysgeusia, suggesting that the lesion is proximal to the stylomastoid foramen. Other possible sites
include the parotid glands secondary to local inflammation, the intracranial course secondary to
meningitis, and intra-axial involvement within the brain stem. In one study of 16 patients with
facial palsy, none had meningitis, suggesting that basal meningitis is an unlikely etiology. Facial
paresis in neurosarcoidosis, when isolated, has a good prognosis in more than 80% of cases, with
or without treatments (Lower et al., 1997).
The eighth cranial nerve is involved in 10% to 20% of cases (Waxman and Sher, 1979), but is
usually asymptomatic. Brain stem auditory-evoked potential abnormalities, however, are more
commonly observed. Bilateral involvement is highly suggestive of neurosarcoidosis. Symptoms
may include either vestibular or hearing dysfunction. They may be acute or chronic and can
fluctuate.
Optic neuropathy has been reported as an uncommon but serious manifestation of
neurosarcoidosis, seen in about 15% of cases (Stern et al., 1985). On the contrary, Zajicek and
colleagues (1999), reported it as the most common neurological manifestation of sarcoidosis in his
series, which is the largest single series of neurosarcoid to date, in which optic nerve or chiasmal
involvement was seen in 38% of the 68 patients with neurosarcoid; of these patients, 69% had
unilateral involvement and 31% had bilateral disease. That can be explained by the results of
Visual Evoked Potentials (VEP) which may reveal frequent abnormalities even in those with no
visual symptoms. Of Oksanen's patients with neurosarcoid, 23 out of 50 patients (48%) had VEP
abnormalities, but only 3 patients had visual symptoms (Oksanen, 1986)
Optic neuropathy manifests as acute or chronic visual loss, with or without pain. It may be
associated with papilledema or optic atrophy. Optic nerve involvement may be difficult to
diagnose and differentiate from optic nerve glioma or meningioma. Papilledema is seen in 14% of
patients with ocular involvement. Rarely, visual impairment occurs because of involvement of the
optic chiasma (Stern et al., 1985).
Oculomotor dysfunction can be caused by involvement of the third, fourth, or sixth nerves in their
courses in the subarachnoid space caused by meningitis and rarely secondary to disease processes
within the brain stem or orbit. Extraocular muscles are rarely involved by sarcoidosis directly.
Pupillary dysfunction is noted occasionally (Graham et al., 1986).
Olfactory nerve dysfunction can present as anosmia or hyposmia and occurs in 2% to 17% of
patients, secondary to subfrontal meningitis or nasal mucosal involvement by sarcoidosis. Nasal
biopsy should be considered in patients with olfactory dysfunction. Other cranial nerves are
rarely involved in neurosarcoidosis.
Meningeal involvement commonly presents as aseptic meningitis. It is reported to occur in up to
64% or as much as 100% of patients in some pathologic studies (Oksanen, 1986). It can occur
occasionally as a meningeal mass lesion. The course of meningitis can vary from an acute
monophasic illness to recurrent episodes. It is usually associated with a good outcome. When
chronic, it is generally associated with multiple cranial neuropathies. Aseptic meningitis is mostly
asymptomatic and only identified in autopsy studies (Delaney, 1977). Occasionally, meningeal
sarcoid mass lesions may present on cerebral imaging as intracranial tumors (Sethi et al., 1986).
Hydrocephalus, which can be either communicating or obstructive, occurs in 6% to 30% of
neurosarcoidosis patients (Oksanen and Salmi, 1986). Mechanisms of hydrocephalus include