Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

546 CHAPTER 16 Neuro-ophthalmology

Supranuclear eye movement disorders (2)

Vertical gaze palsies

Parinaud dorsal midbrain syndrome

Lesions of the posterior commissure and pretectal area result in supranuclear upgaze palsy (saccades affected first, then pursuits, and finally VOR), light-near dissociation, lid retraction, and convergence retraction nystagmus. Causes include hydrocephalus, tumor, trauma, arteriovenous malformations (AVMs), cerebrovascular accident (CVA), and demyelination.

Progressive supranuclear palsy (Steele–Richardson–Olszewski syndrome)

In this neurodegenerative disease of the elderly, there is supranuclear vertical gaze palsy (downgaze affected first, then upgaze, and finally horizontal movements; saccades are affected before pursuits) and lid apraxia (usually seen as failure to blink). Other features include postural instability, Parkinsonism, pseudobulbar palsy, and dementia.

Other supranuclear gaze palsies

Selective upgaze palsy may occur in Wilson’s disease. Selective downgaze palsy with athetosis and ataxia occurs in Niemann–Pick’s disease type C.

Tonic gaze deviation

Raised intracranial pressure or thalamic hemorrhage may cause forced downgaze (“sunset sign”), although it may occur as a transient phenomenon in healthy neonates.

Selective loss of saccades

In Huntington’s disease, there is selective loss of saccades (vertical more than horizontal) which may be compensated for by head thrusts and blinks.

Skew deviation

This is a vertical deviation that is usually concomitant and associated with torsion. Incomitant skews may be confused with CN IV (or CN III) palsies. Skew deviations are usually caused by lesions of the pons or lateral medulla (e.g., CVA, demyelination).

THIRD NERVE DISORDERS 547

Third nerve disorders

A third nerve palsy may be the first sign of an aneurysm of the posterior communicating artery. Unfortunately, it may also be the last sign before the aneurysm ruptures, causing subarachnoid hemorrhage and often death.

Diagnosis may be difficult: a partial palsy may simulate a number of other conditions. Classical teaching associates painful, pupil-involving, progressive palsies with compressive disease (e.g., an expanding aneurysm). However, the differentiation of a compressive from an ischemic third nerve palsy may not be possible on clinical grounds alone.

Classification

Accurate localization greatly assists diagnosis. Identify whether it is

•Complete vs. partial (including aberrant regeneration).

•Pupil-sparing vs. pupil-involving.

•Nuclear, fascicular, or peripheral (nerve palsy).

•Isolated or complex (other neurological defects).

Clinical features

Headache and pain

A severe headache (“worst pain in my life,” “like someone kicked me in the back of the head”) in this context should be assumed to be due to subarachnoid hemorrhage until proven otherwise. Pain is classically associated with compressive lesions but may also occur in ischemia.

Complete

•Diplopia (horizontal and often vertical).

•Complete ptosis, eye abducted, and usually depressed.

Partial

•Any of the above features from near-complete involvement to single muscle paresis (rare).

•Aberrant regeneration is usually associated with long-standing compressive lesions. In lid-gaze dyskinesia, there is lid elevation on adduction (“inverse Duane’s”) or on depression (“pseudo von Grefe”). In pupil-gaze dyskinesia, there is pupil constriction on adduction or depression. Pure eye movement dyskinesias may also occur

(e.g., elevation when trying to adduct).

Pupil involving (cf. pupil sparing)

There is also mydriasis (no light or near response) and difficulty focusing.

Nuclear, fascicular, or peripheral (nerve palsy)

Certain patterns of CN III disorder are localizing (Box 16.5, Table 16.18)

Isolated or complex

Check for involvement of all other cranial nerves, including CN II (especially fields, discs), CN VI (abduction), CN IV (intorsion), cerebellum, and peripheral nervous system (PNS). Other neurological signs may be local (e.g., compressive lesion) or disseminated (e.g., demyelination).

550 CHAPTER 16 Neuro-ophthalmology

Fourth nerve disorders

Superior oblique weakness secondary to CN IV palsy is a common cause of vertical strabismus. One third of cases are congenital, but they may not present until adulthood. Acquired cases are commonly traumatic or due to microvascular infarction. Bilateral CN IV palsy is most commonly due to head injury (see Box 16.6).

Clinical features

•Diplopia (vertical and torsional; worse on downgaze), head tilt (to opposite side), esthenopia.

•Ipsilateral hypertropia/phoria worse on downgaze or on ipsilateral head tilt; compensatory head tilt to opposite side; limited depression in adduction; extorsion (examine fundus: normal foveal position is level with lower third of disc; measure angle with double Maddox rod); may have V pattern.

•Park’s three-step test (p. 32).

Congenital or acquired

A large vertical prism fusion range and high concomitance suggest that the paresis is either congenital or, if acquired, a long-standing lesion.

Unilateral or bilateral

Bilateral palsy is fairly common (particularly after head injury) but may be asymmetric. Typically, there is a reversing hypertropia with L/R on right gaze and R/L on left gaze, a prominent V pattern, and significant excyclotorsion. See Box 16.7.

Isolated or complex

Check for involvement of all other cranial nerves, including CN II (especially fields, discs), CN III, V, and VI, pupils (Horner’s, RAPD), cerebellum, and peripheral nervous system (see Table 16.19). Other neurological signs may be local (e.g., orbital apex lesion) or disseminated (e.g., demyelination).

Investigation

A history of abnormal head posture (check old photographs) or recent trauma may identify the cause. Assess vascular risk factors (atherosclerosis or arteritis; BP, glucose, lipids, ESR, CRP, CBC). The likelihood of ischemic etiology is increased if there is age > 40 years, known vasculopathy, acute onset, nonprogressive characteristic(s), and no additional neurological abnormality.

If etiology is unclear or there is no recovery at 3 months, then investigate further (including MRI). Monitor in conjunction with orthoptists (including Hess/Lees charts and fields of BSV).

Treatment

Orthoptic intervention with a vertical prism (or occlusion) may satisfactorily control diplopia. Surgical options include ipsilateral IO weakening (disinsertion or recession), contralateral IR recession, SO tuck, and modified Harada-Ito. SO tuck carries a significant risk of inducing an iatrogenic Brown’s syndrome.

FOURTH NERVE DISORDERS 551

Box 16.6 Causes of CN IV palsy

•Trauma

•Microvascular infarction

•Tumor (e.g., pinealoma, tentorial meningioma)

•Demyelination

•Vasculitis

•Meningitis

•Cavernous sinus lesions

•Tolosa–Hunt syndrome

•Neurosurgery

•Herpes zoster ophthalmicus

•Congenital

Box 16.7 Features suggestive of bilateral CN IV palsy

•Chin-down head posture (without much tilt)

•Reversing hyperdeviation

•Excyclotorsion >10’

•Prominent V pattern

•Bilateral failure of adduction in depression

Table 16.19 Nuclear and fascicular CN IV syndromes

552 CHAPTER 16 Neuro-ophthalmology

Sixth nerve disorders

Sixth nerve palsy is the most common cause of neurogenic strabismus (for causes of CN VI palsy see Box 16.8). Although CN VI palsy results in an easily recognized abduction deficit, other pathologies may give a similar picture, notably Duane’s syndrome, medial wall orbital fracture, and thyroid eye disease (Box 16.9).

Clinical features

•Diplopia (horizontal; worse for distance and on looking to the side of the lesion), head turn (to same side).

•Esophoria/tropia (worse for distance and on ipsilateral gaze); ipsilateral abduction deficit (ranges from saccadic slowing only, to complete loss of all movement beyond the midline).

Isolated or complex

Check for involvement of all other cranial nerves, including CN II (especially fields, discs), CN III, IV, V, and VII, pupils (Horner’s), cerebellum, and peripheral nervous system (see Table 16.20). Other neurological signs may be local (e.g., the now very rare Gradenigo’s syndrome), disseminated (e.g., demyelination), or reflect iICP (if CN VI palsy is a false localizing sign).

Investigation

Assess vascular risk factors (atherosclerosis or arteritis; BP, glucose, lipids, ESR, CRP, CBC). The likelihood of ischemic etiology is increased if there is age >40 years, known vasculopathy, acute onset, nonprogressive characteristic(s), and no additional neurological abnormality.

If etiology is unclear or there is no recovery at 3 months, then investigate further (including MRI). Monitor in conjunction with orthoptists (including prism cover test, Hess charts, and fields of BSV).

Treatment

Orthoptic intervention with a base-out prism (or occlusion) may satisfactorily control diplopia. Botulinum toxin injection into ipsilateral MR has both a therapeutic and diagnostic role. It may restore BSV and, if only temporary, may be repeated. In any event, it reveals any residual CN VI function that might be augmented by an LR resection/MR recession.

If there is no residual function, then vertical muscle transposition would be required.

554 CHAPTER 16 Neuro-ophthalmology

Horner’s syndrome

The ocular sympathetic supply may be damaged anywhere along its route (see Table 16.21). The extent of sympathetic dysfunction, associated neurological signs, and pharmacological tests may help identify the location of the injury.

Clinical features

•The pupil is miotic with normal light and near reaction.

•Anisocoria is most marked in dim conditions.

•Also ptosis, apparent (but not true) enophthalmos, conjunctival injection; facial anyhydrosis suggests a lesion of the first or secondorder neuron. Iris hypochromia suggests a congenital lesion but may be a longstanding acquired lesion.

Isolated or complex

Check for involvement of all other cranial nerves, including CN II (especially fields, discs), CN III, IV, V and VI, cerebellum, and peripheral nervous system. Other neurological signs may be local (e.g., cavernous sinus pathology) or disseminated (e.g., demyelination).

Also check for history of pain (headache, neck pain, arm pain), trauma or surgery, and any other physical signs, e.g., scars and masses (lung apices, neck, thyroid).

Investigation

Confirm diagnosis

Administer 4% cocaine to both eyes; repeat at 1 min. At 0 and 60 min, measure pupil sizes when fixing on a distant target in identical ambient lighting conditions. A positive test for Horner’s is if there is no or poor dilation to cocaine (blocks reuptake of NorA at the dilator papillae neuromuscular junction).

Identify level

Administer 1% hydroxyamphetamine to both eyes. If there is a firstor second-order neuron lesion, there will be normal dilation; if a third-order neuron lesion, there will be no or poor dilation. This test is seldom performed in clinical practice.

Topical hydroxyamphetamine is expensive and may not be readily available. The test is not reliable if performed within 48 hours of a cocaine test.

Identify etiology

Further investigation is directed by the likely cause and level of lesion (Table 16.22).

Treatment and prognosis

This is dependent on the underlying etiology and may involve urgent referral to neurosurgery, neurology, vascular surgery, or ENT. Any recovery of a Horner’s syndrome also depends on the underlying cause and treatment. In cases associated with cluster headaches (Reder’s syndrome), recovery may occur within a few hours. Invasive tumors may cause relentless irreversible progression.

HORNER’S SYNDROME 555

Table 16.21 Causes of Horner’s syndrome

Many acquired and congenital cases are idiopathic.

CCA, common carotid artery; ICA, internal carotid artery; LN, lymph node.

Table 16.22 Investigations of Horner’s syndrome