Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmology A Systematic Approach 7th Edition_Kanski, Bowling_2011

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Neurofibromatosis

Neurofibromatosis type 1

Neurofibromatosis is a disorder that primarily affects cell growth of neural tissues. Inheritance is AD with irregular penetrance and variable expressivity. The mutation rate is high. The two main types are: (a) type 1 (NF1) and (b) type 2 (NF2). Both may show segmental involvement in which the features are confined to one or more body segments. NF1 (von Recklinghausen disease) is the most common phacomatosis affecting 1 : 4000 individuals. Inheritance is AD with irregular penetrance and variable expressivity with the gene locus on 17q11, though about 50% have new mutations.

Diagnostic criteria

Two or more of the following must be present:

•Six or more café-au-lait macules over 5 mm in greatest diameter in pre-pubertal children, and over 15 mm in greatest diameter in post-pubertal individuals.

•Two or more neurofibromas of any type, or one plexiform neurofibroma.

•Axillary or inguinal freckling.

•Optic glioma.

•Two or more Lisch nodules (iris hamartomas).

•A distinctive osseous lesion such as sphenoid dysplasia or thinning of long bone cortex, with or without pseudoarthrosis.

•A first degree relative (parent, sibling, or offspring) with NF1 by the above criteria.

Systemic features

1Intracranial tumours, primarily meningiomas and gliomas.

2Neurofibromas may develop anywhere along the course of peripheral or autonomic nerves but do not occur on purely motor nerves. They may also involve internal organs.

aDiscrete cutaneous neurofibromas are small, soft, violaceous nodules or larger pedunculated flabby lesions (Fig. 19.100A).

bNodular plexiform neurofibromas feel like a ‘bag or worms’ when palpated. Involvement of the eyelid gives rise to the characteristic S-shaped deformity (Fig. 19.100B).

cDiffuse plexiform neurofibromas may infiltrate widely and deeply into surrounding structures. Associated overgrowth of soft tissue and thick redundant folds of skin may result in considerable disfigurement (elephantiasis nervosa – Fig. 19.100C).

3Skeletal. Short stature, mild macrocephaly (enlarged head), facial hemiatrophy, absence of the greater wing of the sphenoid bone, scoliosis and thinning of long bone cortex.

4Skin

•Café-au-lait spots are light-brown macules that are most commonly found on the trunk (Fig. 19.100D). They appear during the first year of life and increase in size and number throughout childhood; teenagers and adults invariably have more than six.

•Axillary or inguinal freckles usually become obvious around the age of 10 years and are pathognomonic.

5 Associations include malignancies, hypertension and mental handicap.

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Fig. 19.100 Systemic features of NF1. (A) Discrete neurofibromas; (B) nodular plexiformneurofibroma of the eyelid; (C) elephantiasis nervosa; (D) café-au-lait spots

(Courtesy of S Kumar Puri – fig. C)

Ophthalmic features

1Orbital involvement may be caused by one of the following:

aOptic nerve glioma develops in about 15% of patients. It may be unilateral or bilateral and tends to extend posteriorly to involve the chiasm and hypothalamus (Fig. 19.101A).

bOther orbital neural tumours such as neurilemmoma, plexiform neurofibroma and meningioma.

cSpheno-orbital encephalocele is caused by absence of the greater wing of the sphenoid bone (Fig. 19.101B). It characteristically causes a pulsating proptosis, unassociated with either a bruit or a thrill.

2Eyelid neurofibromas, which may be either nodular or plexiform (see Fig. 19.100B), tend to develop early in life. When involving the upper lid, they frequently cause a mechanical ptosis.

3Iris lesions

aLisch nodules (Fig. 19.101C) develop during the 2nd–3rd decades and are eventually present in 95% of cases.

b Congenital ectropion uveae (Fig. 19.101D) is uncommon and may be associated with glaucoma.

cMammillations are rare.

4Prominent corneal nerves may occur.

5Glaucoma is rare and, when present, is usually unilateral and congenital. About 50% of patients with glaucoma manifest ipsilateral neurofibroma of the upper eyelid and facial hemiatrophy.

6Fundus lesions

aChoroidal naevi, which may be multifocal and bilateral, are common. Patients with NF1 and naevi are at increased risk for the subsequent development of choroidal melanoma.

b Retinal astrocytomas, identical to those in tuberous sclerosis, are rare.

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Fig. 19.101 Ocular features of NF1. (A) Sagittal T1-weighted MRimage shows optic nerve glioma invading the hypothalamus; (B) coronal CTimage shows absence of the greater wing of the left sphenoid bone; (C) Lisch nodules; (D) congenital ectropion uveae

(Courtesy of DArmstrong – fig. A; K Nischal – fig. B)

Neurofibromatosis type 2

Neurofibromatosis 2 (NF2) is less common than NF1. Inheritance is AD with the gene locus on 22q12.

Diagnostic criteria

1Bilateral acoustic neuromas (Fig. 19.102) which usually present in the late teens or early 20s with hearing loss, tinnitus or imbalance. Most acoustic neuromas are schwannomas arising from the vestibular nerve. In young patients tumour growth is invariably fast, whereas in older patients the lesion may be either slowor rapid-growing. Recent advances in microsurgical techniques have significantly improved the results of surgery. The gamma knife (stereotactic radiotherapy) provides a therapeutic option.

2A patient with a first-degree relative with NF2 who also has either a unilateral acoustic neuroma or two of the following: neurofibroma, meningioma, glioma, schwannoma or juvenile cataract.

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Fig. 19.102 MRwith enhancement shows bilateral acoustic neuromas. (A) Axial view; (B) coronal view

Ophthalmic features

The following ocular lesions are often the first signs of the disease and may therefore assist in pre-symptomatic diagnosis:

1Cataract affects about two-thirds of patients. The opacities develop prior to the age of 30 years and may be posterior subcapsular or capsular, cortical or mixed.

2Fundus lesions consisting of combined hamartomas of the retinal pigment epithelium and retina, and perifoveal epiretinal membranes are relatively common.

3Ocular motor defects are present in about 10% of cases.

4Less common findings include optic nerve sheath meningioma, optic nerve glioma, unilateral Lisch nodules and an abnormal electroretinogram.

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Migraine

Clinical features

Migraine is often a familial disorder, more prevalent in females, characterized by recurrent attacks of headache widely variable in intensity, duration and frequency. The headache is commonly unilateral, associated with nausea and vomiting and may be preceded by, or associated with, neurological and mood disturbances. However, all these characteristics are not necessarily present during each attack or in every patient. The main types of migraine are discussed below.

Common migraine

Common migraine (migraine without aura) is characterized by headache with autonomic nervous system dysfunction (e.g. pallor and nausea), but without stereotypical neurological or ophthalmic features as in classical migraine (see later).

•Premonitory features include changes in mood, frequent yawning or other non-specific prodromal symptoms such as poor concentration.

•The headache starts anywhere on the cranium and is pounding or throbbing. It usually spreads to involve one half or even the whole head. If retro-orbital, the pain may be mistaken for ocular or sinus disease.

•During the attack, which lasts from hours to a day or more, the patient is frequently photophobic and phonophobic and seeks relief in a quiet dark environment or through sleep.

•Because of the absence of the well-known migrainous visual distortions, severe nausea and vomiting, common migraine often goes unrecognized.

Classical migraine

Classical migraine (migraine with aura) is less common but better recognized.

•The attack is heralded by a visual aura which lasts about 20 minutes. This may consist of bright or dark spots, zig-zags (‘fortification spectra’), ‘heat haze’ distortions, jigsaw puzzle effects, scintillating scotomas, tunnel vision, which may progress to homonymous hemianopia.

•A small bright positive paracentral scotoma develops, lined on one side with luminous zig-zag lines (Fig. 19.103A).

•After several minutes the fortification spectrum gradually enlarges with the open end pointing centrally (Fig. 19.103B).

•It is often lined on the inner edge by an absent area of vision (negative scotoma – Fig. 19.103C).

•As the scotoma expands, it may drift towards the temporal periphery before breaking up (Fig. 19.103D).

•Full visual recovery within 30 minutes is the rule and symptoms persisting longer than an hour should lead to consideration of an alternative diagnosis.

•These visual features, more or less pathognomonic of migraine, may rarely be caused by degenerative arterial disease or arteriovenous malformation in the occipital poles.

•The headache follows the aura by about 30 minutes and is usually hemicranial, opposite the hemianopia and is accompanied by nausea and photophobia. It may, however, be absent, trivial or very severe, with considerable variation between attacks even in the same individual.

•Visual aura without headache (migraine sine migraine) is not uncommon in the over 40s but there should virtually always be a history of common or classical migraine in the patient's early 20s.

•A visual field defect may occasionally be permanent but migraine should be a diagnosis of exclusion in these circumstances.

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Fig. 19.103 Progression of classic migrainous fortification spectrumand scintillating scotoma

Cluster headache

Cluster headache (migrainous neuralgia) is a migraine variant which typically affects men during the 4th–5th decades. It is of particular interest to ophthalmologists because it is associated with ocular features and may initially be misdiagnosed as a local ocular problem. The condition is characterized by a stereotyped headache accompanied by various autonomic phenomena occurring almost every day for a period of some weeks (Fig. 19.104).

•The headache is unilateral, oculotemporal, excruciating, sharp and deep.

•It begins relatively abruptly, lasts between 10 minutes and 2 hours, and then clears quickly.

•The patient cannot keep still and is very agitated, in contrast to a patient with migraine who would rather lie quietly in a dark room.

•It may occur several times in a 24-hour period often at particular times, not infrequently at around 2 a.m.

•Once the ‘cluster’ is over, there may be a long headache-free interval of several years.

•Associated autonomic phenomena include lacrimation, conjunctival injection and rhinorrhoea.

•Cluster headaches are also a common cause of a transient or permanent postganglionic Horner syndrome.

Fig. 19.104 Clinical features of cluster headache

(Courtesy of KE Misulis and TC Head, from Netter's Concise Neurology, Saunders 2007)

Other types of migraine

1Focal migraine is characterized by transient dysphasia, hemisensory symptoms or even focal weakness in addition to other symptoms of migraine.

2Retinal migraine is characterized by acute, transient unilateral visual loss. Since this may occur in middle-aged patients without a past history of migraine, it is prudent to investigate such individuals as undergoing attacks of retinal embolization until proved otherwise.

3Ophthalmoplegic migraine is rare and typically starts before the age of 10 years. It is characterized by a recurrent transient 3rd nerve palsy which begins after the headache.

4Familial hemiplegic migraine is characterized by a failure of full recovery of focal neurological features after an attack of migraine subsides.

5Basilar migraine occurs in children. It is characterized by a typical migrainous aura associated with numbness and tingling of the lips and extremities which is often bilateral. Ataxia of gait and speech also occur, with occasional impairment of consciousness.

Treatment

1General measures include the elimination of conditions and agents that may precipitate an attack of migraine, such as coffee, chocolate, alcohol, cheese, oral contraceptives, stress, lack of sleep and long intervals without food.

2Prophylaxis is indicated if the frequency and/or severity of the attacks are beyond the patient's tolerance. This may involve betaadrenergic blockers, calcium channel blockers, amitriptyline, clonidine, pizotifen and low-dose aspirin.

3Treatment of an acute attack may be with simple analgesics (aspirin, codeine analogues, paracetamol or NSAIDs) and, if appropriate, an anti-emetic such as metoclopramide. Other drugs, usually reserved for patients who are refractory to analgesics, include sumatriptan and ergotamine tartrate.

Differential diagnosis

Visual phenomena

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The visual phenomena of migraine are typically binocular, zig-zag, scintillating and migrate within the visual field. This is often associated with a scotoma and/or homonymous visual loss. A patient may often report loss of vision only in the eye ipsilateral to the hemianopic symptoms. The following conditions should be considered in the differential diagnosis:

1Acute posterior vitreous detachment is characterized by photopsia, usually associated with the sudden onset of floaters. The flashing lights are usually projected into the temporal visual field and may be precipitated by movements of the head or eyes.

2Transient ischaemic attacks due to retinal microembolization are unilateral and not scintillating. The patient often describes a ‘shade’ or ‘cloud’ which typically starts in the upper or lower parts of the visual field and spreads centrally. It lasts several minutes and clears from the centre to the periphery.

3Transient visual obscurations last only a few seconds and are characterized by a ‘greying out’ or ‘darkening’ of vision in one or both eyes. They classically occur in patients with papilloedema and are often precipitated by changes in posture. They may also precede anterior ischaemic optic neuropathy in patients with giant cell arteritis.

4Occipital epilepsy is very rare; the patient typically sees coloured circles during an attack.

Neuralgias

The following conditions should be considered in the differential diagnosis of ocular or periocular pain in the absence of apparent physical disease:

1Herpes zoster ophthalmicus frequently presents with pain 2–3 days before the onset of the characteristic vesicular rash.

2Trigeminal neuralgia is characterized by brief attacks of severe pain that start in the distribution of one of the divisions of the trigeminal nerve. The pain is paroxysmal and sharp, like an electric shock, usually occurring in multiple bursts lasting a few seconds, in rapid succession. Attacks can be triggered either by cutaneous stimulation such as touching the face whilst shaving or by motor activity such as chewing; sleep is usually undisturbed by pain. Facial sensation is normal. Treatment involves antiepileptic drugs such as carbamazepine, phenytoin and sodium valproate. Trigeminal neuralgia of compressive aetiology may necessitate intracranial surgical decompression of the trigeminal nerve.

3Raeder paratrigeminal syndrome typically affects middle-aged men. It is characterized by severe unilateral headache with periocular pain in the distribution of the first division of the trigeminal nerve associated with an ipsilateral Horner syndrome. The pain may last from hours to weeks before it resolves spontaneously. Carotid dissection needs to be excluded before making the diagnosis.

4Greater occipital neuralgia is characterized by attacks of pain that begin in the occipital region and then spread to the eye, temple and face. The attacks frequently occur at night and are associated with flushing of the face, dizziness and sometimes ipsilateral nasal obstruction. Examination during an attack may reveal extreme tenderness between the mastoid process and occipital protuberance.

5Ophthalmodynia periodica is characterized by short, sharp stabbing ocular pain which often causes the patient to place the hand over the involved eye. A second series of episodes may immediately follow the initial attack.

6Ice-pick syndrome is characterized by attacks of momentary, multifocal, sharp, pain around the skull, face and eyes. Unlike trigeminal neuralgia there are no specific trigger points; the pain also does not conform to the anatomical distribution of the trigeminal nerve.

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Facial spasm

Essential blepharospasm

Clinical features

Essential blepharospasm is an uncommon but distressing idiopathic disorder which often presents in the 6th decade and affects women more commonly than men by a 3 : 1 ratio. It is characterized by progressive bilateral involuntary spasm of the orbicularis oculi and upper facial muscles. In severe cases blepharospasm is disabling because it may temporarily render the patient functionally blind (Fig. 19.105). Spasms may be precipitated by reading, driving, stress or bright light, and alleviated by talking, walking and relaxation. It does not occur during sleep.

1 Meige syndrome is a combination of blepharospasm and involvement of the lower facial and neck muscles (Fig. 19.106).

2Brueghel syndrome is associated with severe mandibular and cervical muscle involvement.

Fig. 19.105 Essential blepharospasm

Fig. 19.106 Meige syndrome

(Courtesy of JA Nerad, KD Carter and MAAlford, from Oculoplastic and Reconstructive Surgery, in Rapid Diagnosis in Ophthalmology, Mosby 2008)

Treatment

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Prior to commencing treatment, it is important to exclude reflex blepharospasm, most commonly due to ocular surface disease such as filamentary keratitis, as well as extrapyramidal disease such as parkinsonism.

1Medical treatment with a great variety of drugs has been reported to ameliorate specific types of blepharospasm, but their efficacy is disappointing.

2Botulinum toxin injection along the upper and lower eyelid and eyebrow affords temporary relief in most patients. Interference with acetylcholine release from nerve terminals results in temporary paralysis of the injected muscles. Most patients require repeat injections every 3–4 months; progressively larger doses may be needed. Side-effects include lagophthalmos and ectropion or entropion, depending on the tone of the eyelids before the injection. Accidental migration of the toxin into the orbit may result in ptosis and diplopia due to paralysis of the levator or extraocular muscles.

3Surgical treatment involves stripping of the orbicularis, corrugator and procerus muscles. Such radical surgery is reserved for patients who cannot tolerate or are unresponsive to botulinum toxin.

Hemifacial spasm

Hemifacial spasm is a unilateral condition that presents in the 5th–6th decades of life. It is characterized by brief spasm of the orbicularis oculi which later spreads along the distribution of the facial nerve (Fig. 19.107). The condition may be idiopathic or the result of irritation at any region from the facial nucleus to the peripheral nerve. Neuroimaging should be performed to exclude a compressive aetiology. Facial hyperkinesia may occur several months or years after a Bell palsy. Treatment is similar to that of essential blepharospasm.

Fig. 19.107 Hemifacial spasm

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Chapter 20 – Ocular Side-effects of Systemic Medication

CORNEA 862 Vortex keratopathy  862

Chlorpromazine 863

Argyrosis 863

Chrysiasis 863

Amantadine 863

LENS 863 Steroids 863 Other drugs 863

UVEITIS 863

Rifabutin  863 Cidofovir 864

RETINA 864 Antimalarials 864 Phenothiazines 865

Drug-induced crystalline maculopathies  866

Other drugs 866

OPTIC NERVE 868 Ethambutol 868 Amiodarone  869 Vigabatrin 869 Topiramate 869

Cornea

Vortex keratopathy

Vortex keratopathy (cornea verticillata) is characterized by whorl-like corneal epithelial deposits.

1Signs in chronological order:

•Bilateral, fine greyish or golden-brown opacities in the inferior corneal epithelium.

•Arborizing horizontal lines in a pattern resembling cat's whiskers, similar to the more common Hudson–Stähli line.

•A whorl-like pattern which originates from a point below the pupil and swirls outwards, sparing the limbus (Fig. 20.1A).

•Although deposits may involve the visual axis, vision is not impaired but some patients may experience haloes around lights.

2Causes

aAntimalarials

•Chloroquine (Nivaquine, Avlocor) and hydroxychloroquine (Plaquenil) are quinolone antimalarial drugs used in the prophylaxis and treatment of malaria as well as in the treatment of certain rheumatological disorders (e.g. rheumatoid arthritis, juvenile chronic arthritis, systemic lupus erythematosus). The use of chloroquine has also been advocated in the treatment of calcium abnormalities associated with sarcoidosis.

•Unlike retinopathy (see below), keratopathy bears no relationship to dosage or duration of treatment. The changes are usually reversible on cessation of therapy, although they may clear despite continued administration.

bAmiodarone

•Amiodarone is an anti-arrhythmia drug used in the treatment of ventricular tachycardia and fibrillation, and in restoration of sinus rhythm in atrial fibrillation.

•Common systemic side-effects include thyroid dysfunction, pulmonary toxicity, peripheral neuropathy and gastrointestinal problems.

•Virtually all patients eventually develop keratopathy which is slowly reversible on discontinuation of medication. In general the higher the dose and the longer the duration of administration the more advanced the corneal deposits.

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