Ординатура / Офтальмология / Английские материалы / The Neurology of Eye Movements_Leigh, Zee_2006

360 The Diagnosis of Disorders of EyeMovements

per day. The attacks may be brought on by looking downward, by tilting the head toward the side of the affected eye, or by blinking. Most patients with superior oblique myokymia have no underlying disease, though cases have been reported following trochlear nerve palsy, head injury, possible demyelination or

brain stem stroke, and with cerebellar tumor.261'433-62?

The eye movements of superior oblique myokymia are often difficult to appreciate on gross examination, but the spasms of torsional-vertical rotations can sometimes be detected by looking for the movement of a conjunctival vessel as the patient announces the onset of symptoms (see VIDEO: "Superior oblique myokymia"). They are more easily detected during examination with an ophthalmoscope or slit

magnetic search coil technique has demonstrated an initial intorsion and depression of the affected eye, followed by irreg-

ular oscillations of small amplitude (Fig. 9-17).365'433>627 The frequency of these os-

cillations is variable; some resemble jerk nystagmus at frequencies of 2 to 6 Hz, but superimposed upon these oscillations are

low-amplitude, irregular oscillations with frequencies ranging up to 50 Hz.

Electromyographic recordings from superior oblique muscles affected by the disorder have revealed abnormal discharge from some muscle fibers, either spontaneous or following contraction of the muscle.261'325'331 These discharge abnormalities include prolonged duration, increased amplitude, and polyphasic pattern, with a spontaneous discharge rate of approximately 45 Hz. Spontaneous activity is only absent with large saccades in the "off" (upward) direction. Those fibers having an irregular discharge following muscle contraction subside to a regular discharge of about 35 Hz. These findings have been interpreted as indicating neuronal damage and subsequent regeneration, leading to desynchronized contraction of muscle fibers. Experimental lesions of the trochlear nerve have demonstrated regenerative capacities such that the remaining motoneurons increase their number of ax-

Figure 9-17. Superior oblique myokymia (see VIDEO: "Superior oblique myokymia"). A shows a typical attack affecting the right eye, which the patient induced by blinking (b). The affected right eye depressed and intorted, and high frequency oscillations were superimposed. B compares the torsional position of the right eye and left; note that the high frequency oscillations of superior oblique myokymia are only present in the right eye; the left eye shows some drift and nystagmus that is typical in the torsional plane for normal subjects during fixation. LT, left torsional; RH, right horizontal; RV,right vertical; RT, right torsional. Upward deflections indicate rightward, upward, or clockwise rotations, from the point of view of the subject. Eye position is relative, individual records having been offset to aid clarity of display.

ons to hold the total constant.266'671 Patients with superior oblique myokymia usually do not report a prior episode of diplopia, but MRI studies sometimes show atrophy of the superior oblique muscle,406

and it seems possible that mild damage to the trochlear nerve could trigger

individual patients may respond to car-

myokymia spontaneously resolves,73 but in others the symptoms are so troublesome that surgical treatment is considered, and a modification of the Harada-Ito procedure—nasal transposition of the anterior portion of the superior oblique tendon, to weaken cyclorotation—has been beneficial.335

Oculomotor Nerve Palsy

CLINICAL FEATURES OF OCULOMOTOR NERVE PALSY

The third cranial nerve supplies four extraocular muscles (medial, superior and inferior recti, and inferior oblique) and the levator of the lid and contains parasympathetic fibers that supply the sphincter of the pupil and the ciliary body.

A complete, peripheral third nerve palsy is easily recognized by ptosis; a fixed, dilated pupil; and a resting eye position that is "down and out" (see VIDEOS: "Oculomotor nerve palsy"). Incomplete third nerve palsies, however, are more common, and characteristic patterns of loss of function can be correlated with lesions at various sites along the course of the nerve from nucleus to muscle. It is necessary to differentiate such patterns of muscle weakness from a variety of restrictive ophthalmopathies, and from myasthenia gravis

tant, since some underlying conditions— notably aneurysms—require prompt therapy (Table 9-7). An MRI often helps to confirm the underlying cause.56

NUCLEAR OCULOMOTOR

NERVE PALSY

Lesions of the nucleus of the third nerve are rare. When they occur, they usually involve adjacent structures important for vertical conjugate gaze. Based on current knowledge of the anatomic organization of the oculomotor nucleus (Fig. 9-9), it is possible to set certain criteria for diagnosis of nuclear third nerve palsy;124 these are summarized in Table 9-8. However, it is important to recognize that in this small area of the midbrain, the nuclei and fascicles of the oculomotor nerve lie in close proximity, and both may be affected to varying degrees. At present, MRI findings may not provide sufficient resolution to

differentiate between nuclear and fascicular lesions.67'378-509

When nuclear lesions affect the superior rectus subnucleus, elevation of both eyes is impaired.78'203 This is because axons from one superior rectus subnucleus cross and pass through the fellow subnucleus of the opposite side.53'711 Thus, a lesion of one superior rectus subnucleus is effectively a bilateral lesion. It follows that in those case reports when only one superior rectus muscle—either ipsilateral or contralateral to the side of the lesion—is involved, the lesion must have involved the superior rectus nerve fascicles (i.e., axons after they have left the nucleus).

Similarly, when lesions affect the central caudal nucleus, the result is bilateral ptosis. This is because of the unpaired nature of the central caudal subnucleus that supplies the levator muscle (Fig. 9-9). Since the central caudal nucleus sits at the bottom of the oculomotor nuclear complex, it may be selectively affected and bilateral ptosis may be the only manifestation of the nuclear palsy. The "plus-minus" lid syndrome of unilateral ptosis and contralateral eyelid retraction has been reported in association with nuclear third lesions.202 If raising the ptotic lid does not abolish the contralateral lid retraction (which would be expected according to Hering's law of the eyelids),24 and if the lesion is acute (i.e., there has not been time for aberrant reinnervation), then the eyelid retraction in such cases is most probably due to loss

Nuclear

Congenital hypoplasia234'269'508

Infarction or hemorrhage202'203-322'339

Tumor307'510

Trauma630

Infection16-554'636

Fascicular

Infarction96-344'438

Hemorrhage183'301'344

Demyelination193'643

Syphilis663

Trauma30-305

Subarachnoid

Aneurysm (typically posterior communicat ing artery; occasionally basilar

artery)220'22 J,306,434,653,673,690

Meningitis (infectious, syphilitic, granulomatous, Lyme, and neoplastic)44'241'282'418-507'541'636

Nerve infarction (associated with diabetes)680 Tumors of the oculomotor nerve3'491-515'697 Neurosurgical complication418'703

Trauma305

At the Tentorial Edge

Uncal herniation495'526

Pseudotumor cerebri402

Hydrocephalus534

Trauma342

Cavernous Sinus and Superior Orbital Fissure

Aneurysm of internal carotid artery37'319'459 Carotid-cavernous fistula7'313'347'422

Cavernous Sinus and Superior Orbital Fissure—continued

Cavernous sinus thrombosis672

Internal carotid artery stenosis,31 or dissection546

Tumor: pituitary adenoma, meningioma,

nasopharyngeal carcinoma, metastases, angioma, other1'76'194-295.321'458'463

Pituitary infarction (apoplexy)414'514-529

Nerve infarction (associated with diabetes, hypertension, or arteritis)19'157'528'625 or

hemorrhage423

Sphenoid sinusitis and mucocele280 Herpes zoster17

Tolosa-Hunt syndrome22

In association with monoclonal gammopathy and Waldenstrom's macroglobulinemia68'353

Orbit*

Trauma368

Mucormycosis and other fungal infections512 Tumor and other infiltrates566

Frontal or sphenoidal sinus mucocele159'560'609

Localization Uncertain

In association with viral and other infections, and following immunization97'309'556

In association with cancer chemotherapy591 or cocaine413

Nerve infarction129'236 Migraine479'613-691

Following dental488 or retrobulbar anesthesia132

of inhibition of the levator. The origin of this inhibition is undetermined, but it appears to emanate from the nucleus of the posterior commissure, which synapses in the M-group of neurons before reaching the central caudal nucleus. Since ptosis is unilateral, the lesion cannot be localized to the central caudal nucleus (even though other parts of the oculomotor nucleus are), and the ptosis is fascicular in origin.

The medial rectus neurons lie at three locations within the nucleus, so it would

seem unlikely for medial rectus paralysis (unilateral or bilateral) to be the solemanifestation of a nuclear third nerve palsy.

Similarly, because the visceral nuclei are spread throughout the rostral half of the nucleus, unilateral internal ophthalmoplegia is unlikely to be the sole manifestation of a lesion of the oculomotor nucleus. Involvement of the pupil with midbrain

third nerve lesion suggests a rostral site in the nucleus.537

The third-nerve nucleus also houses oculomotor internuclear neurons, which project to the contralateral abducens nucleus. Experimental studies indicate that they play a role in coordinating conjugate eye movements and that pharmacological inactivation of these internuclear neurons

Table 9-8. Diagnosis of Nuclear

Oculomotor Nerve Palsy*i24,203

Obligatory Lesions

Unilateral third nerve palsy with contralateral superior rectus paresis and bilateral partial ptosis

Bilateral third nerve palsy associated with spared levator function (internal ophthalmoplegia may be present or absent)

Possible Nuclear Lesions

Bilateral total third nerve palsy Bilateral ptosis

An isolated weakness of any single muscle except the levator, superior rectus, and medial rectus muscles

Conditions That Cannot Be Due to Nuclear Lesions

Unilateral third nerve palsy, with or without internal involvement, associated with normal contralateral superior rectus function

Unilateral internal ophthalmoplegia Unilateral ptosis

Isolated unilateral or bilateral medial rectus weakness

*In the absence of pupillary involvement, ocular myasthenia must always be ruled out.

with lidocaine causes a contralateral abduction weakness.106 We have observed abduction weakness in the eye contralateral to a midbrain lesion that caused a third nerve palsy.

Paralysis of the inferior rectus and inferior oblique muscles in isolation is theoretically possible but is usually associated with conjugate vertical gaze disorders. Patients reported to have impaired depression of one eye associated with impaired

elevation of the other with or without adduction paresis of the higher eye133'167'677

most probably had skew deviation rather than nuclear oculomotor palsy.586 Disruption of saccadic inputs from the riMLF have sometimes been invoked to account for vertical disconjugacy in patients with lesions involving the oculomotor nucleus. However, the demonstration of axon collaterals from saccadic burst neurons in the riMLF (see Fig. 6-5), which contact yoke muscle pairs in the oculomotor and trochlear nuclei,435 means that violations of Hering's law for vertical saccades must reflect lesions within or close to the mo-

toneurons. This issue is discussed further in Chap. 10 (see Display 10-25).

CONGENITAL OCULOMOTOR NERVE PALSY

Congenital palsies of the third nerve are usually incomplete and unilateral; aberrant reinnervation is a common associated finding (see below).34'234 The location of the lesion is variable and may be associated with other developmental anomalies.214'234 Rarely, congenital oculomotor weakness may alternate with periodic spasms of third nerve overactivity such as esotropia or miosis; this is called oculomotor palsy with cyclic spasms.186'381 This syndrome

sometimes occurs with acquired oculomotor palsies;329'640 its pathogenesis is un-

known.

Ophthalmoplegic migraine usually has its onset in childhood.27 The oculomotor palsy is usually complete, but rarely just the superior ramus is affected.293 The palsy typically lasts for days or weeks after the headache has resolved. Rarely, patients are reported with congenital limitation of ocular motility that suggests anomalous innervation of muscles normally supplied by the oculomotor nerve. One example is a syndrome of congenital, unilateral adduction palsy; when the patient attempts to look into the field of action of the weak medial rectus muscle, the affected eye abducts rather than adducts

(synergistic divergence). Electromyographic studies suggest a pattern of anomalous innervation which is analogous to the abnormality in Duane's retraction syndrome (see above).119-670 Slowly progressive third nerve palsy in childhood may, in some cases, be due to schwannoma of the nerve sheath that can be detected with imaging

studies,3 but in others no cause can be found.324'424

DISORDERS AFFECTING THE FASCICLES OF THE OCULOMOTOR NERVE

As the fascicles of the oculomotor nerve traverse the midbrain, they pass through important structures that enable precise localization of third nerve palsies.379 If the oculomotor nerve is involved as it tra-

364 The Diagnosis of Disorders of Eye Movements

verses the cerebral peduncle, a contralateral hemiparesis will result, called Weber's syndrome.574 Involvement of the oculomotor fascicles, red nucleus, and superior cerebellar peduncle causes Claude's syndrome: oculomotor palsy, contralateral ataxia, asynergy, and dysdiadochokinesis. More extensive lesions may affect the third nerve fascicles, cerebral peduncle, and adjacent red nucleus and substantia nigra, causing Benedikt's syndrome: oculomotor palsy, contralateral hemiparesis, and contralateral involuntary movements or tremor. Dorsal midbrain lesions that involve the oculomotor nucleus and produce a combination of nuclear and supranuclear gaze limitation with ataxia have been called Nothnagel's syndrome.379

The third nerve may also be affected by hemorrhages caused by downward herniation of the brain stem. Small midbrain lesions may selectively involve the fascicles of the oculomotor nerve, causing paresis of one or more of the extraocular muscles with no associated neurologic

deficits.96-198-263'344'345'470* Thg pattern Qf

involvement of the third nerve has been used to advance theories for the topographic organization of the oculomotor fascicles (see Anatomy of the Oculomotor Nerve, above).

DISORDERS AFFECTING THE

SUBARACHNOID PORTION OF THE OCULOMOTOR NERVE

After its exit from the brain stem, the third nerve runs in the subarachnoid space and is susceptible to meningeal processes (infection, tumor, blood) and compression by arterial aneurysm. Basilar artery aneurysms can cause oculomotor nerve palsy,639 but the internal carotid-posterior communicating arterial junction is the more common site. With these aneurysms, it is unusual for the pupil to be affected alone; ptosis and external ophthalmoplegia usually coexist. With posterior communicating aneurysms, third nerve palsy may occur in the setting of subarachnoid hemorrhage, but another presentation is of acute diplopia with facial or orbital pain but without subarachnoid hemorrhage. Occasionally, minor head trauma may pre-

cipitate oculomotor nerve palsy due to aneurysms or tumors.673 A common clinical challenge is to differentiate third nerve compression due to aneurysm from nerve infarction in association with diabetes or hypertension (see below), in which cerebral arteriography is not indicated. The presence of pupillary involvement can be relied on to identify those patients that

harbor an aneurysm. Initially, however, the pupil may be spared,37'319'459 so pupil-

sparing third nerve palsy requires careful observation for a week before a decision can be made about arteriography. After

aneurysm.298 Cases of complete extraocular palsy with normal pupils due to aneurysm are rare.385 Partial pupillary involvement may be grounds for an arteriogram,320 although mild involvement of the pupil may occur with noncompressive processes.60 Pleocytosis in the cerebrospinal fluid may occur with aneurysm.306 Spontaneous resolution of an oculomotor paresis does not necessarily mean that aneurysm is excluded.220 Another factor that should be weighed when considering arteriography for acute oculomotor palsy is the patient's age: Individuals between 20 and 50

years of age are more likely to have an

aneurysm,638 whereas children younger than 11 years almost never do.690 MRI and

angiography often help to differentiate nerve infarction from compressive or brain stem lesions,56 and gadolinium enhancement of the cisternal portion of the oculomotor nerve is a sensitive index of neoplastic or inflammatory processes, including migraine.613

COMPRESSION OF THE

OCULOMOTOR NERVE AT

THE TENTORIAL EDGE

The third nerve may also be compressed against the tentorial edge, the petroclinoid ligament, or clivus by the uncus of the temporal lobe during transtentorial herniation.495 Alternatively,the third nerve may be stretched by displacement of the midbrain.526 Classically, the pupillary fibers are affected first and mydriasis results. When the pupil becomes fixed, extraocu-

lar muscle weakness also appears. Rarely, upward herniation of a posterior fossa mass lesion may cause a third nerve palsy.

DISORDERS AFFECTING THE

CAVERNOUS PORTION OF THE OCULOMOTOR NERVE

Within the cavernous sinus (Fig. 9-8), the oculomotor nerve may be compressed by aneurysm or tumor. Intracavernous (infraclinoid) aneurysms are less common than posterior communicating (supraclinoid) aneurysms and seldom rupture. The typical presentation of intracavernous aneurysms is progressive ophthalmoplegia and ptosis, often with signs of aberrant reinnervation.390 About half of all patients suffer pain in the face. Often the abducens and trochlear nerves are also affected. Symptoms are usually slowly progressive and may suggest tumor. Sparing of the pupil is more common with aneurysms involving the cavernous sinus than with posterior communicating aneurysms, probably because the inferior division of the oculomotor nerve, which contains the pupillomotor fibers, is less frequently involved in the former.638 An alternative explanation is that sympathetic paresis and parasympathetic paresis coexist. Rarely, the aneurysm ruptures and creates a ca- rotid-cavernous fistula (see below).

Tumors arising near the cavernous sinus, including meningioma, pituitary adenomas, and lymphomas, may cause third nerve palsy; usually other nerves in the cavernous sinus are also affected. Typically, the tumors grow slowly without producing any pain. Sometimes, the diagnosis only becomes evident with serial MRIs. Occasionally, hemorrhage occurs into a pituitary tumor, causing the syndrome of pituitary apoplexy as in the following case history.

CASE HISTORY: Pituitary apoplexy

A 56-year-old man suddenly developed nausea and vomiting, which lasted for 24 hours and then resolved. The next day,he noticed a mild headache; several hours later, he suddenly developed diplopia and a left, partial ptosis. On examination, he had normal visual acuity and

full visual fields. His left pupil diameter was 6 mm and his right was 5 mm. There was a left exotropia and hypotropia; testing showed weakness of all extraocular muscles supplied by the left oculomotor nerve but sparing of the lateral rectus and superior oblique (seeVIDEOS: "Oculomotor nerve palsy"). He was hypertensive but had no neck stiffness, and results of the general neurologic examination were normal. A CT showed possible enlargement of the sella turcica. A carotid arteriogram showed no aneurysm. A spinal tap revealed a protein of 57 mg/dL, glucose of 54 mg/dL, 200 red cells/ mm3, and 4 white cells/mm3. An MRI showed a pituitary tumor that extended laterally on the left to compress the oculomotor nerve (Fig. 9-18). The patient was treated with corticosteroids and underwent a successful transsphenoidal resection of his tumor. Histological examination demonstrated hemorrhage in a chromophobe adenoma.

Comment: This case illustrates several features of pituitary apoplexy: sudden onset of headache (usually severe), variable degrees of ophthalmoparesis (which may be bilateral and complete), and subarachnoid hemorrhage. Visual loss and endocrine insufficiency may also occur. A CT or MRI confirms the diagnosis. Prompt transsphenoidal neurosurgical intervention, preceded by massive corticosteroid administration, is usually required.487'514'681

Septic thrombosis of the cavernous sinus is now rare,152 but low-grade inflammatory processes may cause oculomotor nerve palsy as part of the Tolosa-Hunt syndrome (see below).

INFARCTION OF THE

OCULOMOTOR NERVE

Solitary third nerve palsy may be due to infarction, usually in association with diabetes or hypertension ("medical third"). It is also reported in association with collagen vascular disease or giant cell arteritis.129 The pupil is usually spared or only minimally involved,2733 though it may occasionally be fixed to light.209 Patients often complain of facial or orbital pain that usually precedes the muscle palsy and disappears when diplopia or ptosis develops.

The onset of diplopia is sudden but the muscle paresis may evolve for up to 2 weeks.274 Recovery is usually the rule within 3 months.90 Although it generally occurs in diabetic patients who already have evidence of small-vessel disease in other organs, third nerve palsy may be the presenting feature of the disease and it has been reported in children with dia-

betes.225 Pathologic examination of the third nerve in diabetic patients has shown

infarction of the nerve in the intracavernous19'157 or subarachnoid portions.680

The core of the nerve is most severely involved, thus sparing the peripherally located pupillary fibers. The oculomotor nerves of diabetics who have not suffered third nerve palsy showmicrofasciculation

of edge fibers and changes in the distribution of fiber size.585 Other studies, however, suggest that a common site of nerve infarction in diabetics is within the brain stem.255 Coexistent involvement of the oculomotor nerve and the trochlear nerve or of all three ocular motor nerves and the ophthalmic division of the trigeminal nerve probably implies occlusion of branches of the inferolateral trunk that arises from the intracavernous carotid artery.356 Mucormycosis must always be considered in the diabetic patient who develops ocular musclepalsies.

OCULOMOTOR NERVE PALSY DUE TO TRAUMA

In most large series of patients with oculomotor nerve palsy, trauma is an important cause. The head injury usuallycauses frac-

ture or loss of consciousness; only rarely does palsy follow mild trauma, and then other diagnoses, such as tumors at the base of the skull, should be considered.170 The third nerve may be injured as it emerges from the brain stem (root avulsion) in its subarachnoid course as it attaches to the dura, or by fractures at the supraorbital fissure. Penetrating injuries to the orbit or brain may also cause third nerve palsy.305

ABERRANT REGENERATION OF THE OCULOMOTOR NERVE

A common sequel of oculomotor nerve palsy is aberrant regeneration. Ramon y Cajal first showed that after experimental transection of the oculomotor nerve, the regenerating fibers no longer follow their previous paths but innervate different

muscles supplied by the third nerve.511 Other studies have confirmed such misrouting of axons.178'572-573 This cannot be the mechanism in every case, however, since anomalous synkinesis can occur

transiently after an acute third nerve

palsy.369'572-573

The clinical signs of aberrant regeneration include abnormal lid movements. Most commonly the lid elevates during adduction or depression of the eye. Other common patterns include depression of the lid on abduction, and pupillary constriction on adduction or depression of the eye, but absent direct pupillary light reaction. All these combined movements are due to cocontraction of muscles innervated by the third nerve. Rarely, the lid of the other eye may be affected with elevation on down gaze.228 Acquired oculomotorabducens synkinesis has been reported.281

Aberrant reinnervation of the oculomotor nerve may occur after trauma,552 aneurysm,580'653 congenital third nerve palsy,34 migraine,54 or as a complication of neurosurgery.270 If aberrant regeneration is encountered without a history of preceding oculomotor palsy, then slowly growing intracavernous meningioma66'545 or carotid aneurysm116 is likely, though sometimes no cause can be found.351 Aberrant regeneration almost never occurs with diabetic third nerve palsy. Aberrant regeneration in which misdirected fibers of the abducens nerve came to innervate the pupil has been proposed as the explanation of miosis with abduction in a patient who suffered palsies of CN III, IV, and VI following head trauma.489

PARTIAL OCULOMOTOR NERVE PALSY

As the oculomotor nerve passes through the cavernous sinus, it divides into superior and inferior rami or divisions. The superior oculomotor division supplies the superior rectus and levator palpebrae superioris; the inferior oculomotor division supplies the other extraocular muscles, the pupil, and the ciliary body.

Isolated lesions of these branches occur.74,120,161,464,540,609 Tne pattern of weak-

ness encountered with a superior division lesion can be produced, however, by le-

sions located in the more proximal portions of the nerve,229'230 or even within the

brain stem.344 Less commonly, individual

muscles supplied by the third cranial nerve may be paralyzed.96'439'510'668 In patients

with isolated ptosis or paralysis of individual muscles, myasthenia gravis should be considered. Rarely, double-elevator palsy, with no tropia in central position, is due to a brain stem lesion (see Chap. 10).

MANAGEMENT OF OCULOMOTOR NERVE PALSY

Complete oculomotor palsy is easily diagnosed, but with partial involvement, consideration should be given to whether the patient has another condition (Table 9-4). In adults, a common challenge is to determine whether the palsy is due to nerve infarction in association with diabetes or hypertension, or is due to a compressive lesion such as arterial aneurysm. If the pupil is completely fixed to light, the chance of aneurysm is high, and angiography is usually indicated. Patients with partial involvement of the pupil and complete involvement of the extraocular muscles and lid should undergo MRI-MRA and be closely observed. An MRA will reveal some but not all aneurysms compressing CN III. It is wise to closely observe all patients who have developed a third nerve palsy for several days, since their signs may evolve and cerebral angiography may become indicated. Anisocoria of greater than 2 mm may be considered grounds for an arteriogram.638a An MRI may also demonstrate brain stem infarction or hemorrhage, and gadolinium enhancement may demonstrate inflammation or infiltration affecting the oculomotor nerve throughout its course.56 Oculomotor nerve palsy in children is less likely to be due to aneurysm, but if there has been no antecedent trauma, cerebral tumors should be sought with MRI.324

Multiple Ocular Motor

Nerve Palsies

The principal culprits causing combined third, fourth, and sixth nerve palsies are

brain stem stroke, lesions within the cavernous sinus or superior orbital fissure (where the three nerves lie near each other), trauma, and generalized neuropathies (Table 9-9). Any of these processes can lead to complete ophthalmoplegia.299 Other causes to be considered in the patient with complete ophthalmoplegia include neuromuscular disorders (myasthenia gravis, Miller Fisher syndrome, and botulism), drug intoxications (see Table 10-21), and Wernicke's encephalopathy.

ment in advanced cases,425'469 although other brain stem nuclei may be involved.23 This rarity of involvement has been related to the peculiarly low concentrations of glycinergic and muscarinic cholinergic receptors of these nuclei, when compared with other cranial nerve nuclei or the spinal cord.683 Abnormalities of eye movements in ALS are discussed in Chap. 10. Limitation of eye movements has been de-

scribed in some forms of spinal muscular atrophy.224-480

BRAIN STEM LESIONS CAUSING

OPHTHALMOPLEGIA

Infarction or hemorrhage of the brain stem may limit horizontal and vertical eye movements;299'693 diagnostic features are described in Chap. 10. A combination of ocular motor nerve palsies, with brain stem lesions, is encountered in some pa-

tients with acquired immune deficiency syndrome (AIDS).237'303 The nuclei of the

ocular motor nerves are usually spared in amyotrophic lateral sclerosis (ALS), with only rare pathologic reports of involve-

CAVERNOUS SINUS AND SUPERIORORBITAL

FISSURE SYNDROMES

Within the cavernous sinus (Fig. 9-8), a variety of disease processes may affect the ocular motor nerves. To differentiate cavernous sinus from orbital apex lesions, associated findings are helpful.71 Involvement of the first two sensory divisions of the trigeminal nerve suggests disease of the cavernous sinus; if all three divisions are involved, a retrocavernous process may be present. If trigeminal function is

Brain stem

Tumor534

Infarction or hemorrhage299'632'693

Encephalitis215

Subarachnoid

Meningitis (infectious and neoplastic)380-507 Trauma302'368

Clivus tumor

Aneurysm and dolichoectasia158

Cavernous Sinus and Superior Orbital Fissure

Aneurysm of internal carotid artery182-390

Occlusion of internal carotid artery201'687 Tumor: meningioma, pituitary adenoma with apoplexy, cavernous angioma or hemangiopericytoma, nasopharyngeal

carcinoma, lymphoma, myeloma,

Waldenstrom's macroglobulinemia,

Other20'138>251,352,383,401,445,497,514,558,620

Pseudotumor cerebri355 Cavernous sinus thrombosis152'672

Cavernous Sinus and Superior Orbital Fissure—continued

Tolosa-Hunt syndrome87'212-265'631 Neurosurgical complication703 Herpes zoster17

Nerve infarction (associated with diabetes or arteritis)128'337'410

Carotid-cavernous fistula217'313'372

Orbital*

Mucormycosis and other infec-

tions121'279'362'512'710

Trauma399

Tumor and other infiltrates332

Localization Uncertain

Generalized neuropathies, especially postinflammatory type (Guillain-Barre and

Miller Fisher syndromes)181-409

Sjogren's syndrome396 Toxins622

Behget's disease460