Neuroophthalmology
Marc J. Dinkin
Don C. Bienfang
DISORDERS OF LID POSITIONPtosis
Background
Slight asymmetries of lid position are common; usually the patient is the best source of information regarding their importance.
Pathophysiology
The major muscle holding the lid up is the levator palpebrae innervated by the third cranial nerve; a minor muscle is Müller muscle innervated by the sympathetic nervous system.
Prognosis
Prognosis is a function of cause.
Diagnosis
1. Most acquired cases of upper lid ptosis that come to the attention of a neurologist raise the question of partial third nerve palsy or myasthenia gravis or the mild ptosis of Horner syndrome.
2. The ptosis of myasthenia usually demonstrates several special features: When it is lifted by the physician, the contralateral lid may droop a bit (curtaining). It may improve after eye closure for 15 minutes (rest test), application of ice for 1 minute (the ice test), or with edrophonium (Tensilon test).
3. The ptosis of a Horner syndrome is associated with ipsilateral miosis and sometimes anhydrosis. It may lift with topical application of the alpha agonist, apraclonidine.
4. If these entities have been ruled out by examination and appropriate testing, most seemingly “new” cases of upper lid ptosis will in fact prove to be old if photographs, such as driver’s license, are reviewed.
5. Local trauma, ocular surface injury, and chronic use of topical steroids are other causes.
6. Levator dehiscence, a detachment of the levator tendon from its insertion, may occur with aging, from contact lens use or after cataract surgery.
Treatment
1. Mild and severe lid ptosis of any etiology can be helped by surgical procedures that lift the lid as described in Volume 4 of Albert and Jakobiec’s The Principles and Practice of Ophthalmology.
a. Caution must be exercised because there is a risk that in myopathies the ptosis may be the first expression of what later will involve other eye muscles.
b. If the surgical procedure leaves the patient with a partial inability to close the lid and the patient loses the protective Bell reaction later, a corneal ulcer may develop. This is particularly common in cases of chronic progressive ophthalmoplegia.
2. In some cases “lid crutches” fitted to the back of a pair of glasses by a skilled optician can be helpful.
3. Taping of the lid to the forehead is often unsuccessful in the long run.
Lid Retraction
Background
This entity is often confused with exophthalmos, which it mimics.
Pathophysiology
1. The majority of cases of acquired upper lid retraction are due to thyroid eye disease. The two major mechanisms are overstimulation of the sympathetic fibers to Müller muscle and scarring of the levator palpebrae muscle or the lid itself. In such cases it may be accompanied by a lid lag, or deficiency of lid lowering during downgaze, sometimes referred to as Von Graefe sign.
2. When lid retraction is caused by a dorsal midbrain injury (i.e., Parinaud syndrome), it is called Collier sign. It occurs when posterior commissure fibers, which inhibit the central caudal nucleus (which innervates the levator palpebrae muscles), are damaged.
3. Ptosis of the lid of the opposite side and weakness of the ipsilateral superior rectus are other causes.
Prognosis
This is a function of etiology.
Treatment
1. An ophthalmic plastic surgeon can weaken the small sympathetically driven Müller muscle to correct this problem (see Volume 4 of Albert and Jakobiec’s Principles and Practice of Ophthalmology).
2. In cases of thyroid lid retraction, an equally successful and simpler procedure is to create a small laterally placed adhesion between the upper and lower lids. This is done by abrading equal lengths of the lid margin of the upper and lower lid and then bringing them into anatomic apposition by means of a suture that passes through both lid margins in a mattress stitch fashion. It should be left in place 2 to 3 weeks and then removed.
3. Although one might expect that successful treatment of the thyroid would eliminate this problem, unfortunately this is not always the case.
ASYMMETRIC PUPILS (ANISOCORIA)Background
In the absence of strabismus or any other neurologic findings, most pupil asymmetries will turn out to be physiologic or due to a local cause.
Pathophysiology
Since the pupil is innervated by both the sympathetic system (which dilates the pupil) and the parasympathetic system (which constricts via the third cranial nerve), there is a long list of neurologic conditions that can lead to anisocoria through disruption of either system. The most essential entities to diagnose quickly are an aneurysmal third nerve palsy, which typically affects pupillary function early, and a Horner syndrome from a carotid dissection, which is a risk factor for a stroke.
Prognosis
Abnormally small pupils rarely cause much problem for the patient unless there is a cataract present. Large pupils result in glare from light.
Diagnosis
Although asymmetric pupils are a common problem, many cases are not an expression of serious pathology. Two simple general principles can be applied to determine which pupil is abnormal, the large one or the small one. First, the abnormal pupil is the one that does not move normally. Second, if anisocoria is greater in bright light, the problem is with the larger pupil not constricting adequately, either from iris sphincter injury, an Adie pupil, or oculomotor nerve palsy. If the anisocoria is worse in the dark, the likely cause is a Horner syndrome, which is preventing the smaller pupil from dilating. Specific eye drops confirm a Horner syndrome and localize the lesion along the three neuron system (Table 15-1). Various drops can be used to determine the cause of a dilated pupil (Table 15-2).
Treatment
1. Small pupils, such as from Horner syndrome, cause little problem to the patient and can be ignored.
2. The droopy lid of Horner can be fixed surgically if necessary.
3. Dilated pupils, as from an Adie pupil, third cranial nerve palsy, or as an effect of drugs or trauma, cause more visual problems and may require treatment.
a. If the pupillary sphincter is responsive, a drug such as pilocarpine can be used to make the pupil smaller. Unfortunately, this is not without its dangers. Pilocarpine is an uncomfortable drug to the patient and can cause retinal detachment. The lowest possible dosage that is effective should be used. Commercially this is 0.25%. It may have to be used two to three times a day to maintain miosis.
b. Another solution is the fitting of a contact lens that has a painted ring at the periphery artificially, thus making a small aperture.
4. Before any of the above measures are taken, management of the underlying cause of the anisocoria is critical (e.g., repair of aneurysm causing a third cranial neuropathy, anticoagulation for a carotid dissection causing a Horner syndrome).
TABLE 15-1 Drops Used to Confirm and Localize a Horner Syndrome | ||||||||||||||||||||
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TABLE 15-2 Drops Used to Determine the Cause of a Dilated Pupil | |||||||||
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DISORDERS OF EYE MOVEMENTSMyopathies
Degenerative Myopathies
Background Slowly progressive and often with a suggestive family history, this group of entities expresses itself in many parts of the body in addition to the eye. The patient may have limitation of extraocular motility and bilateral ptosis. The pupil is spared (Table 15-3).
TABLE 15-3 Myopathies Affecting Extraocular Muscles | ||||||||||||||||||||||||
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Pathophysiology Some myopathies affecting the extraocular muscles reflect a disorder of the mitochondria, giving rise to the “ragged red fibers” seen pathologically, while others result from somatic mutations affecting myocyte function. The strabismus in mitochondrial myopathies is often symmetric so that the patient experiences no diplopia.
Prognosis These entities usually have a steady downhill course over a prolonged period.
Diagnosis The diagnosis depends on characteristic clinical, biopsy, and electrophysiologic findings.
Treatment
1. Degenerative myopathies of the ocular muscles such as chronic progressive external ophthalmoplegia (CPEO) are largely not treatable in any way that would restore normal eye movement. A special caution must be exercised since these conditions often present first with lid ptosis before there are other expressions.
2. If a surgical procedure is done to lift the lid and later the patient loses Bell reaction as the superior rectus loses function or develops a weakness of orbicularis function, a corneal ulcer may develop. (Treatment for this is discussed in the section on seventh nerve palsies.) This is such a frequent sequence of events that the experienced ophthalmologist learns to recognize that a corneal ulcer after surgery is a common first clue that a patient has CPEO.
3. Because lid ptosis is so disfiguring and disturbing visually, lid crutches in this condition are the best solution. Once the extraocular muscle weakness has reached a steady state, prism glasses can be given to allow single binocular vision in most cases. Prisms are especially effective in this condition since there is little or no eye movement.
Myopathy of Graves Disease
Background Autoimmune effect on the extraocular muscles in some patients with Graves disease leads to muscle hypertrophy, diplopia, proptosis, and if severe, compressive optic neuropathies.
Pathophysiology
1. The muscles most commonly affected are the inferior rectus and the medial rectus, in that order, resulting in diplopia.
2. The muscle becomes inelastic and stiff and restricts movement in the direction of its agonist.
3. Progressive proptosis often occurs, which may help protect the eye from optic nerve compression.
Treatment
1. Thyroid eye disease is usually responsive to a combination of muscle recession operations and prism.
2. Surgery should be delayed until the active phase of the orbitopathy has passed.
3. Intravenous (IV) steroid treatments may decrease the inflammation and reduce symptoms in some cases.
4. Radiation to the orbit is sometimes used in severe cases, but its efficacy remains in question and it may be complicated by post-radiation side effects.
5. In the case of optic nerve injury, removal of a bony wall of the orbit can decompress the nerve and prevent further loss of vision.
Orbital Trauma
Background
Direct mechanical trauma to the orbit can result in a bewilderingly complex array of eye movement disorders, either by restricting extraocular muscles or injuring ocular motor nerves. The principles of management share many features.
Pathophysiology
1. It is in this group of entities that detailed computed tomography (CT) imaging of the orbital walls and contents is indispensable, as its ability to show bony abnormalities is superior to magnetic resonance imaging (MRI).
2. One has to make decisions rapidly about the cause of ocular muscle dysfunction. As time passes, scarring becomes an issue that will complicate later repairs; thus, any problems such as entrapment of muscle in fractures and muscle disinsertions from the globe need to be dealt with surgically early on. At the same time, a remarkable amount of orbital deformity can be well tolerated.
3. Hemorrhage or inflammation of or around the affected muscle may develop later.
Prognosis
The prognosis depends entirely on the cause and degree of damage.
Diagnosis
This is usually straightforward given the history.
Treatment
1. When a final status has been reached, combinations of muscle surgery with appropriate prism fine tuning can have as their goal at least some degree of single vision in the straight-ahead and downgaze positions.
a. These are the most important positions for adults to have single vision and should be the first goal of all therapies.
b. If this cannot be achieved, a patch, usually on the eye with the worse motility, may be the only solution.
2. Iatrogenic trauma to eye muscles is also common after cataract, retina, orbital, and sinus surgery. A large proportion of these seem to be restrictive myopathies, and appropriate recessions of the affected muscles are usually in order. Peribulbar anesthesia may cause trauma to the muscle cone and appears to be of highest incidence in the left eye reflecting a greater difficulty in precise injection by righthanded surgeons.
DISORDERS OF THE NEUROMUSCULAR JUNCTIONMyasthenia Gravis
Background
The subject of myasthenia gravis as it affects the eye is so similar to generalized myasthenia that the reader is referred to this subject in Chapter 9.
Prognosis
When ocular myasthenia gravis occurs in isolation (without systemic myasthenia), there is approximately a 50% chance that the patient will develop systemic symptoms within 2 years.
Treatment
1. The challenge of ocular myasthenia is its fluctuation. This makes prism fitting and surgical therapeutic solutions an option only in the rare case that stabilizes. Given the nature of the disease, this decision may be difficult and hazardous.
2. A particular problem with the use of prisms in this condition, and many of those described in this chapter, is that the double vision may vary greatly depending on the direction of gaze. One can often only hope to get the patient visually aligned in straight-ahead and downgaze positions; even this may require two sets of glasses.
a. A device that artificially blurs the vision in one eye is often the easiest solution; however, this need not be a patch, which calls attention to the patient.
b. Adequate blurring without as much cosmetic disfigurement can be accomplished by “frosting” one lens of a pair of glasses. Clear nail polish applied to a lens and then patted with the finger before it dries is an inexpensive solution.
3. One might think that lid ptosis by occluding one eye should be a good solution for the diplopia. Patients differ on this as a droopy lid is very disfiguring. Many patients prefer to have the lid propped up by a crutch or with tape even though they have double vision as a result.
4. The systemic therapy for pure ocular myasthenia is little different from treatment of generalized myasthenia and is discussed in general neurology texts. If the ocular problem can be dealt with easily by the patient, systemic therapy should be limited to those most easily tolerated, such as cholinesterase inhibitors and episodic use of corticosteroids. Some observational studies have concluded that systemic steroid therapy may lower the conversion rate to systemic myasthenia gravis, but there have been no conclusive trials to date.
Botulism
Background
Flaccid paralysis may be caused by the botulinum toxin, which is released by the bacterium Clostridium botulinum and may contaminate certain foods or bodily wounds. The toxin is usually preformed in food, but is elaborated by bacteria in wound infection.
Pathophysiology
The botulinum toxins inhibit acetylcholine release at the presynaptic neuromuscular junction. Flaccid paralysis ensues.
Diagnosis
Botulism should be suspected in any patient with paralysis beginning in the ocular muscles and “descending” to the limbs and respiratory muscles, without sensory symptoms. The main features are nausea, vomiting, dysphagia, diplopia, dilated or fixed pupils, and an extremely dry mouth refractory to drinking fluids. Autonomic and respiratory weakness may develop. The toxin may be isolated in serum, stool, or recently consumed foods. Single-fiber electromyography can confirm localization to the neuromuscular junction.
Prognosis
Recovery occurs over 1 to 3 months. Survival is 90% to 95% with intensive care, but delayed treatment and older age predict a less favorable outcome.
Treatment
1. Rigorous supportive and respiratory care is the mainstay of treatment to keep the patient alive through the illness.
2. Trivalent A-B-E antitoxin can slow disease progression although it will not speed reversal of active symptoms. Serum sickness occurs in a subset of patients.
DISORDERS OF THE OCULAR MOTOR NERVESThird Cranial Nerve Palsies
Background
This occurs mainly with aging, diabetes, tumor, and aneurysm. An evaluation to determine the cause is more important with this nerve than with cranial nerves IV or VI.
Pathophysiology
1. Partial third nerve palsies only imply that the cause has not completely destroyed the nerve; it should not be reassuring.
2. In a complete palsy, sparing of the pupil is reassuring that an aneurysm is not the cause, although rare exceptions occur.
3. The third nerve separates into a superior (superior rectus and levator palpebrae) and inferior (medial, inferior, superior recti, inferior oblique, and parasympathetic fibers) branch in the anterior cavernous sinus, so isolated superior or inferior branch lesions can help pinpoint localization.
4. Nuclear third nerve palsies cause bilateral ptosis (the central caudal nucleus innervates bilaterally) and may affect elevation of the contralateral eye (the superior rectus fibers decussate).
Prognosis
1. If tumor or aneurysm is the cause, the prognosis for recovery is poor, especially if the paralysis has been present for a long time and if aberrant regeneration has begun.
2. Pupil-sparing palsies in which the cause is believed to be vasculopathic have a better prognosis, although several months may pass before resolution.
Diagnosis
It is not the purpose of this chapter to provide a complete evaluation of third nerve palsies. But because myopathies, myasthenia, and a number of other conditions can deceive the physician, it is wise to evaluate patients in whom a third nerve palsy is suspected with special caution.
Treatment
1. A well-established, complete third nerve palsy is challenging for correction by prism or surgery, and the patient’s expectations should be modified accordingly.
a. The first and most hoped for therapy is time.
b. During this time, it is probably best that a patch, if necessary, be alternated on a daily basis between the two eyes.
c. Most idiopathic third cranial nerve palsies will express most of their resolution within the first 2 to 3 months.
d. Surgeons often wait 6 months before considering surgery.
2. The surgical repair of paralytic ocular muscle palsies for the most part depends on the presence of some tone in the weak muscle and another functioning muscle whose tone can be grafted to the tone of the dysfunctional muscle. In the case of third cranial nerve palsies, the only muscle available for transplantation is the superior oblique, which may have its insertion moved close to that of the superior rectus.
a. In a complete third nerve palsy, adjustable sutures are advised. The ptosis that some patients consider cosmetically unacceptable can usually be helped by appropriate surgery, but the double vision now exposed remains a challenge. Reports of successful outcomes are at the case report level and not routinely expected.
b. If the third nerve palsy is partial, there may be options for the combination of surgery and prism usage with a goal of at least single vision in straight-ahead and in straight-ahead down positions.
c. Later on, if aberrant regeneration emerges, the situation becomes even more complex.
Fourth Cranial Nerve Palsies
Background
Fourth nerve (trochlear) palsies produce vertical and torsional diplopia, although many patients only recognize the vertical component. In contrast to third cranial nerve palsies, fourth cranial nerve palsies can usually be treated with a number of maneuvers.
Pathophysiology
The fourth nerve exits the dorsal lower midbrain and decussates to innervate the contralateral superior oblique muscle, which depresses the eye when adducted, intorts the eye, and contributes to abduction. Most acquired cases are caused by head trauma or are idiopathic. Congenital fourth nerve palsies are common and often unrecognized by the patient.
Prognosis
There is often considerable or complete spontaneous recovery of idiopathic palsies in 2 to 3 months. The prognosis in traumatic cases is not as good; in these cases the palsies may be bilateral.
Diagnosis
1. The affected eye elevates on adduction. Head tilt to the shoulder with the higher eye on adduction makes the hypertropia worse but to the opposite side makes it better. The patient sees a horizontal line as two lines that come closer together at one end pointing like an arrow to the affected eye.
2. Diplopia is worst in downgaze contralateral to the affected eye.
3. Careful inspection of the fundus may reveal excyclodeviation of the eye.
4. The first clue to bilateral fourth nerve palsy is that the patient prefers a chin-down position to a head tilt. This is because there is typically an exotropia that is improved in upgaze. Otherwise the diagnosis of bilateral fourth nerve palsy can be challenging.
5. Injury to the trochlear nucleus or fascicles within the midbrain is rare and results in a contralateral fourth nerve palsy.
Treatment
1. The patient may have already discovered that tilting the head to the side opposite the weak muscle solves many of the double-vision problems.
a. For many partial fourth nerve palsies, the major problem for the patient is vertical double vision in downgaze. A separate pair of reading glasses with a vertical prism may be all that is needed.
b. If the vertical deviation is beyond what can be solved by prism (usually when the total prism power would have to be in the teens), muscle surgery may be necessary. The fourth cranial nerve is very long and if the axon damage is close to the cell body, the regenerating axons may take several months to reach the muscle.
2. Another approach is surgical weakening of the ipsilateral antagonist, the inferior oblique. This operation simultaneously addresses the torsional problem and the hyperdeviation. In long-standing fourth nerve palsies this is not adequate to correct diplopia. Depending on the measurements in the various fields of gaze, surgery on the contralateral muscles that control vertical movements, the superior rectus, and inferior rectus and even the ipsilateral vertical movers may be necessary.
Sixth Cranial Nerve Palsies
Background
Because of the straightforward nature of this problem it provides an excellent example of the difference in therapy of a muscle weakness versus the therapy of a muscle paralysis.
Pathophysiology
The long course of this nerve in isolation from other brain stem structures increases the potential causes of dysfunction. The sixth nerve exits the pons, travels superiorly up along the clivus bone, enters Dorello canal, traverses the cavernous sinus, and then enters the orbit. Extremes in intracranial pressure (high or low) may produce bilateral sixth palsies, as the nerve is forced against the superior aspect of the clivus.
Prognosis
Prognosis depends on the cause but in cases of ischemic mononeuropathy, maximum recovery can be expected in 2 to 3 months.
Diagnosis
1. If the lateral rectus muscle is completely paralyzed, the eye will abduct only as far as the midline. This is accomplished by the relaxation of the medial rectus plus the normal elastic forces within the orbit.
2. Reaching the midline is not evidence of active contraction of the lateral rectus. Later, the eye will not even reach the midline as the medial rectus contracts.
Treatment
1. If there is no evidence of active lateral rectus function, there is no procedure one can do on that muscle to make it function better. The only solution is to bring in muscle tone from other muscles, usually the superior and inferior rectus muscle of the same side, using a muscle-sharing procedure.
a. The medial rectus muscle can be weakened by means of a recession and chemodenervation with Botox (5 units), but this alone will not be enough to straighten the eye. Some active tone must be supplied by a functioning muscle to counteract the tone in the medial rectus.
b. The analysis can be complicated by medial rectus contraction even though there is some lateral rectus tone.
c. To discover this situation, perform a test in which the eye is grasped by some device and active contraction against this hold by the lateral rectus with the eye in the adducted position is demonstrated.
2. If there is tone in the lateral rectus as evidenced by abduction beyond the midline or by active pulling on the forceps when the eye is adducted and the patient is asked to abduct, tightening by means of shortening the muscle but leaving its insertion on the globe unchanged will move the position of the eye laterally into alignment with the fellow eye.
a. Experienced eye muscle surgeons have a rough idea of how much tightening to do along with weakening of the medial rectus by means of recessing the insertion on the globe in order to achieve alignment.
b. The weakening of the medial rectus can be done in such a way that the muscle insertion location can be adjusted after the effect of the anesthetic is over (the adjustable suture technique).
3. Surgery is not usually considered until all hope of spontaneous recovery has passed, usually 6 months.
a. As a sixth nerve palsy recovers, there is usually a period during which the patient has single vision in part of the horizontal field of gaze and diplopia in the rest. During this period partial taping of the lens to block vision in the eye with the weak muscle may be useful.
b. Most clinicians who deal with these problems encourage patients to exercise the paretic eye muscle. This is done by alternately patching one eye on 1 day and the other eye on the next.
c. Again, as with the third and fourth, in milder cases a prism in the glasses may suffice.
Seventh (Facial Motor) Cranial Nerve Palsies
Background
This condition is commonly seen in any center with an active neurological service.
Pathophysiology
The seventh nerve is vulnerable to inflammation- (e.g., Lyme disease, sarcoidosis, Guillain-Barré syndrome), trauma-, and tumor-induced damage. Idiopathic seventh nerve palsies (i.e., Bell palsy) is felt to be due to HSV1. If the lesion is proximal, weakness of the muscles of facial expression may be accompanied by hyperacusis (nerve to the stapedius) and changes in taste (chorda tympani). Lower motor neuron facial palsies include the frontalis muscle but it is spared in upper motor neuron lesions due to bilateral cortical supranuclear control.
Prognosis
There are two overriding principles that govern the prognosis in this condition.
1. If the paralysis of motor function is not associated with any anesthesia of the cornea, it becomes much less likely that there will be any scarring and loss of vision.
2. The second principle is that surgical closure of the lids should be done sooner rather than later. A common mistake is to wait until advanced ulceration or even scarring has developed before performing a tarsorrhaphy. Attempts to rectify the problem late in the course often result in permanent damage to the eye.
Diagnosis
Seeing how well the patient can close the eye most easily makes diagnosis.
Treatment
1. In mild cases—in which there is some preservation of lid closure a good Bell’s reaction, and the ultimate prognosis for recovery is good—treatment with intense daytime lubrication, (usually the most viscous drops one can obtain) or and ointment at night may be sufficient. Manual closure of the eye by the patient’s finger frequently during the day duplicates the blink.
2. In general, patching of the eye is disappointing.
a. The ability of an eye to open under even the firmest of patches is remarkable. Under such a circumstance one not only has an open lid but also has the added possibility of the patch rubbing against the corneal surface.
b. If the patient or a friend is skilled and motivated, the use of tape, frequently attended to and changed after thorough cleaning of the skin of the lids, can keep the lid closed and is especially useful overnight.
3. A surgical lid closure should be done early in most cases that are likely to last for more than a few weeks.
a. Often it is enough to bring the lateral lid margins together allowing just enough of an aperture medially to allow inspection of the eye and especially the cornea. A common technique is to abrade the lid margins and bring them in apposition to one another with a heavy suture on a bolster. The suture can be removed in a couple of weeks. An advantage of this is that the tarsorrhaphy can be gradually taken down as the condition improves. A disadvantage is that the lid margin and lashes are often permanently scarred in an unpleasant way. Also this technique is less useful if the medial portions of the lids must also be closed. There is more pull at this level and the skin bridge that forms between the lids can stretch out to create an unsightly band across the interpalpebral fissure.
b. A stronger bond using less of the lid margin can be created by splitting the lid on the gray line (the most superficial portion of the orbicularis oculi) for just 1 or 2 mm of depth. The two raw surfaces from the upper and lower lids can be brought together with an absorbable mattress suture. This bond is very strong, uses only a small amount of lid margin to be effective, and can be used medially as well as laterally.
4. Another approach is the insertion of gold weights into the upper lid, the use of springs, and reinnervation of the facial musculature by nerve grafting. These techniques are best handled by an experienced plastic surgeon.
5. If the corneal exposure has evolved to the point of frank ulceration, a soft contact lens in addition to lid closure may be necessary as a temporary aid to healing. Even so, a scar is likely.
6. Timely medical treatment of the underlying process (e.g., prednisone when appropriate for idiopathic Bell palsy) can speed recovery and reduce risk to the cornea. In the case of Bell palsy, treatment within 48 hours appears to reduce the risk of permanent weakness.
Multiple Cranial Nerves
Background
In general, the occurrence of deficits in III, IV, V1, V2, sympathetic fibers, and VI reflect cavernous sinus disease. Orbital apex syndrome may include all of the above except V2, with the addition of reduced acuity from damage to the optic nerve (Table 15-4).
Pathophysiology
Depending on the location, in most cases something of considerable size or capable of spread is necessary to cause such an entity. Cancer, granulomas and certain infections are the usual causes.
Prognosis
1. The best resort is that resolution of the underlying disease will alleviate the problem.
2. The next best hope is that there will be enough balance between opposing groups (III vs. VI) that the eye will be in an almost straight-ahead position barring complete ptosis of the upper lid, which makes the whole issue moot. In general these situations are complex and different from case to case; thus, therapy may be unique for each case.
3. This is an entity that is often detected too late for effective therapy.
Mucormycosis
Pathophysiology
Mucormycosis is a fungus with broad nonseptate hyphae that branch at right angles. It causes vascular invasion and damage, but can also infiltrate ocular and orbital structures directly. It is typically seen in diabetic patients or patients with longstanding steroid use.
TABLE 15-4 Syndromes of Multiple Cranial Neuropathies | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Diagnosis
Patients typically have headache and facial pain, and may have proptosis or orbital cellulitis. Visual disturbances may result from strabismus by way of orbital apex or cavernous sinus disease. Visual loss can occur through invasive optic neuropathies or retinal/choroidal infarcts.
Prognosis
This condition progresses rapidly and has a poor prognosis, especially once it is apparent that the infection has spread beyond the sinuses.
Treatment
1. Consultation with ear, nose, and throat (ENT) and infectious disease specialists will be necessary. Often a biopsy, not a culture, of the nasal tissue will be necessary to confirm the diagnosis.
