Multiple Cranial Neuropathies

Craig G. Carroll, D.O.; William W. Campbell, M.D., M.S.H.A.

Disclosures

Semin Neurol. 2009;29(1):53-65. 

In This Article

Disorders of Cranial Nerve Groups

In some locations, two or more cranial nerves are bundled in a common anatomic space, and when a focal disease process occurs, the entire cluster of nerves may be involved. Most often, disorders of cranial nerve groups are due to mass effect and are commonly secondary to neoplasms. As with the vascular brainstem syndromes, many of these carry eponyms. Many of these syndromes are rare, however, in neurologic practice. Familiarity with the more common of these syndromes may aid in localization when the relevant cranial nerves are involved. Relatively common anatomical syndromes involve the cavernous sinus, the cerebellopontine angle, and the jugular foramen.

Cavernous Sinus Syndrome

The cavernous sinuses are paired venous channels that lie on either side of the sphenoid bone and sella turcica, lateral to the pituitary. They extend from the superior orbital fissure to the apex of the petrous temporal bone. The two sides are connected by an anterior and posterior inter cavernous sinus. The internal carotid artery with its pericarotid sympathetic plexus runs through the sinus whereas the oculomotor, trochlear, abducens, and trigeminal nerves (1st and 2nd division) pass laterally on its wall. Common signs and symptoms of cavernous sinus disease include ophthalmoplegia, orbital congestion, chemosis, periorbital edema, proptosis, and facial sensory loss as well as Horner's syndrome from involvement of the sympathetics. According to Keane's series, the cavernous sinus was the most frequent site of multiple cranial nerve involvement representing 25% of cases.[2] Common causes can be divided into vascular, neoplastic, inflammatory, and miscellaneous disorders. In severe cases, all of the nerves passing through the sinus may be involved; however, isolated involvement of individual nerves also occurs, especially the abducens nerve. A Horner's syndrome in conjunction with an abducens palsy is particularly localizing.

Of the vascular causes, carotid aneurysms, carotid cavernous fistulas, and thrombosis need to be considered. If large enough, intracavernous aneurysms may compress and distort the contents of the cavernous sinus, often resulting in an indolent painful ophthalmoplegia. Intracavernous aneurysms do not have a significant risk of subarachnoid hemorrhage. When rupture does occur, it tends to remain local and may result in formation of a cavernous-carotid fistula.[49] A carotid cavernous fistula is a communication between the carotid artery and the cavernous sinus. These may be further classified into direct or indirect fistulas. In direct fistulas, the cavernous carotid artery and cavernous sinus are in direct continuity. These often develop spontaneously from a ruptured cavernous aneurysm as above, or may be secondary to trauma, such as a closed head injury. They are characterized by the classic triad of chemosis, pulsatile exophthalmos, and an audible bruit over the eye on auscultation. These often require complex interventional management.[49] In indirect fistulas, shunts are established through meningeal branches from the carotid system. These tend to be more insidious with arterialization of the conjunctival vessels without an audible bruit and often resolve spontaneously. Cavernous sinus thrombosis usually results from paranasal sinus infections, orbital cellulitis, or a facial infection (such as a furuncle). Staphylococcus is the most common causative organism; however, pneumococcal and fungal infections should also be considered, particularly in immunocompromised individuals and diabetics. In diabetics, mucormycosis is of particular concern.

Tumors are the most common cause of cavernous sinus syndrome.[49] These may be metastatic disease, a result of local tumor extension (nasopharyngeal carcinoma, pituitary adenoma or craniopharyngioma) or a primary tumor (meningioma, lymphoma). Finally, the cavernous sinus syndrome can result from any inflammatory granulomatous processes such as sarcoidosis, Wegener's granulomatosis, or polyarteritis nodosa. Another inflammatory disorder that must be considered is Tolosa-Hunt syndrome. This is an idiopathic inflammatory granulomatous disorder that typically presents with painful ophthalmoplegia. Once mass lesion has been excluded, it is the most common cause of cavernous sinus syndrome. Although spontaneous remission occurs in up to a third of patients, the universally positive response to steroids is often regarded as a diagnostic criteria.[49] One must consider, however, that other processes, such as tumors (especially lymphoma) may also show an initial response to steroids.

Cerebellopontine Angle

The boundaries of the cerebellopontine angle include the inferior surface of the cerebellar hemisphere, the lateral aspect of the pons, and the superior surface of the inner third of the petrous ridge. It spans longitudinally from CN V through CN X. Lesions of the cerebellopontine angle are invariably neoplasms, most of which are benign. Vestibular schwannomas are by far the most common tumor, arising from the vestibular portion of CN VIII within the internal auditory canal. Less common neoplasms include meningiomas, epidermoids, and much less commonly metastases and cholesteatomas. The initial symptoms are usually progressive sensorineural hearing loss and tinnitus. Because of the slow-growing nature and the ability of the vestibular system to compensate, frank vertigo is unusual; however, gait dysequilibrium is not uncommon. As the mass expands, cranial nerve dysfunction ensues accompanied by dysfunction of CN VII causing a lower motor neuron facial paresis without hyperacusis. CN V dysfunction causing facial sensory loss is also common. CNs VI, IX and X are less commonly involved, usually later in the course. If the lesion continues to grow, pressure on the cerebellum or its peduncles result in ipsilateral ataxia and incoordination. Nystagmus and gaze palsies may result from pontine compression.

Lower Cranial Nerve Syndromes

The lower cranial nerve syndromes involve CNs IX-XII unilaterally in various combinations. These nerves exit the skull just above the foramen magnum. CNs IX-XI exit through the jugular foramen along with the jugular vein. CN XII exits through the hypoglossal canal just inferiorly. The symptoms of lower cranial nerve disease, including dysphagia, dysphonia, and dysarthria are common reasons for neurologic consultation. Therefore, a knowledge of the cranial foramina and their contents, as well as the relationship of structures near the skull base, are essential for the neurologist who will invariably encounter one of the many diseases that can affect this area.

Jugular foramen syndrome, or Vernet's syndrome, is the prototype lower cranial nerve syndrome, characterized by ipsilateral paralysis of CNs IX, X, and XI. This syndrome is caused by a lesion at the jugular foramen or in the retroparotid space. Glomus tumors (paragangliomas) are common causes of jugular foramen syndrome. They are benign, usually spontaneous, slow-growing head and neck tumors that are thought to arise from widely distributed paraganglionic tissue that originates from the neural crest cells. Glomus tumors commonly arise in the jugular bulb (glomus jugulare), the middle ear (glomus tympanicum), and the nodose ganglion of the vagus nerve (glomus vagale). Although slow growing, they may erode through bone and extend into the jugular foramen or even into the hypoglossal canal. Other common inciting lesions are schwannomas, meningiomas, and metastases. Rarer causes include retroparotid abscesses, chordomas, and thrombosis of the jugular bulb. The term jugular foramen syndrome is often used to refer to any combination of palsies affecting the lower four cranial nerves; however, several other eponymic syndromes deserve mention. Collet-Sicard syndrome, or intercondylar space syndrome, consists of jugular foramen syndrome (dysfunction of CNs IX, X and XI) with additional involvement of CN XII. Villaret's syndrome is Collet-Sicard plus the addition of sympathetic involvement (Horner's syndrome). This is also referred to as the retropharyngeal space syndrome. If the inciting process extends into the retroparotid space, there may be additional CN VII involvement. The same etiologic considerations apply for all these syndromes; therefore, from a practical standpoint, considering all collectively as jugular foramen syndromes stands to reason. Finally, although not technically a lower cranial nerve syndrome, the petrous apex syndrome can progress to include the lower cranial nerves. Otherwise known as Gradenigo's syndrome, this syndrome is typically associated with suppurative otitis media affecting the petrous apex of the temporal bone. It typically presents with pain in a trigeminal nerve distribution combined with abducens palsy. If the infection spreads to the skull base, then features of jugular foramen syndrome may coexist.

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