Fig. 44-5), as do basilar invagination and Chiari malformation. Several lower cranial nerves may be involved on one side by a carotid artery dissection. A successive involvement of all cranial nerves on one side has been referred to as Garcin syndrome, or hemibasal syndrome. It has been reported in chondromas and chondrosarcomas of the clivus, but may occur with nasopharyngeal carcinomas. Bone erosion is likely to be seen radiographically in these cases. Table 44-2 lists the main causes of multiple cranial nerve palsies of extramedullary origin in our experience.
The question of viral infections of cranial nerves is always raised by acute neuropathies of the facial, trigeminal, and vestibulocochlear nerves, especially when the condition is bilateral, involves several nerves in combination, or is associated with a pleocytosis in the spinal fluid. Actually, the only proved viral etiologies in this group of cases are herpes simplex, herpes zoster, and cytomegalovirus infections. Because neural deafness, vertigo, and other cranial nerve palsies have been observed in conjunction with the postinfectious encephalomyelitides of
Mycoplasma, varicella, measles, rubella, mumps, and scarlet fever, they probably share an immune-mediated mechanism. Multiple or single cranial nerve palsies of abrupt onset may precede or accompany infectious mononucleosis and sometimes other viral or mycoplasmal diseases. DeSimone and Snyder assembled a series of 20 such cases associated with mononucleosis; bilateral facial paralysis was the most common presentation, bilateral optic neuritis the next most common, and in 3 cases, 3 or 4 cranial nerves were involved. The prognosis is excellent.
Some cases formerly thought to be postinfectious in nature may be true infections of the nerve. The same may be said of the single and multiple cranial nerve palsies that are sometimes associated with HIV and CMV infections. Treatment of the parainfectious cases is symptomatic; the prognosis for recovery is good in many cases. Quite often one observes an acute or subacute form of multiple cranial neuropathy of undetermined cause. Juncos and Beal reported on 14 cases of this type, incorporating 6 well-documented cases of the Tolosa-Hunt orbitocavernous sinus syndrome with oculomotor palsies. In the group that was not attributable to Tolosa-Hunt, the onset was with facial pain and headache (temporofrontal), followed within days by abducens palsy (12 of 14), oculomotor palsy (6 of 14), trigeminal palsy (5 of 14), and facial weakness (4 of 14), and less often by involvement of the eighth, ninth, and tenth cranial nerves (unilaterally in most instances). Increased CSF protein and pleocytosis occurred in several. The prompt relief of pain upon administration of steroids was similar to that obtained in the Tolosa-Hunt syndrome. The mode of recovery, which usually occurred within a few months, was also much the same in the 2 groups of patients. Juncos and Beal concluded that the clinical features of the 2 groups overlapped and that their separation into 2 syndromes was arbitrary. We have seen a relapsing form of this illness in young adults, responsive on each occasion to steroids and stabilizing after several years. Numerous tests of the CSF by polymerase chain reaction revealed no viruses. Conceivably, some of these cases represent variant forms of GBS, in as much as they may be preceded by a nonspecific infection and may at times be accompanied by areflexia or evanescent paresthesias and elevated CSF protein without pleocytosis. Others probably are examples of the entity described by Juncos and Beal, possibly reflecting a granulomatous process in the pachymeninges.