Cranial nerve and eye muscle palsies

Chapter 83 Cranial nerve and eye muscle palsies

Chapter contents

INTRODUCTION

CONGENITAL IIIRD NERVE PALSY: CLASSIFICATION

ACQUIRED IIIRD NERVE PALSY

IVTH NERVE PALSY

ACQUIRED IVTH NERVE PALSY

VITH NERVE PALSY

MULTIPLE OCULAR MOTOR PALSIES/COMPLEX OPHTHALMOPARESIS

AUTOIMMUNE OCULAR MOTOR DISTURBANCES IN CHILDHOOD

OCULAR MUSCLE DISEASE

OCULAR MYOSITIS

Introduction

Apart from congenital IVth nerve palsy, childhood congenital and acquired infranuclear ocular motor palsies are uncommon. Because of this and concerns about the potential serious underlying pathology, these cases are usually referred to specialist centers. However, the principles of history taking, examination, diagnosis, and documentation are the same as those applied to more routine ocular motility cases. All ophthalmologists whose practices include child referrals should be familiar with the investigation and management of these cases and establish a network of contacts with pediatric neurology and neuroimaging colleagues to optimize outcomes.

Congenital IIIrd nerve palsy: classification

Bilateral

A. Congenital cranial dysinnervation disorder (CCDD) (see Chapter 82). This is the commonest cause of bilateral congenital IIIrd nerve palsy. Inherited genetic mutations lead to primary maldevelopment of either the IIIrd (CFEOM1) or the IIIrd and IVth cranial nerve nuclei (CFEOM2). Clinical features include bilateral ptosis and symmetrically reduced elevation and adduction. High resolution MRI shows cranial nerve hypoplasia.¹

B. Rarely, sporadic bilateral infranuclear congenital IIIrd nerve palsy has been described usually in association with extensive neurodevelopmental anomalies.

Unilateral congenital IIIrd nerve palsy

A. Clinical features suggesting pre- or perinatal peripheral IIIrd nerve damage, viz. variable IIIrd nerve innervated muscle involvement and signs of misdirection regeneration. The palsy may be isolated or associated with additional perinatal neurologic damage (Fig. 83.1).²

B. With features suggesting a primary nuclear maldevelopment, viz. bilateral partial ptosis and contralateral superior rectus palsy. A hypoplastic peripheral IIIrd nerve may be seen on MR imaging and specific genetic mutations known to be associated with CCDD identified.

C. Unilateral congenital IIIrd nerve palsy has also been reported in:

• Neurofibromatosis 2 (NF2) – this can be the presenting feature.

• PHACE syndrome. The posterior fossa malformations described include unilateral IIIrd nerve palsy (Fig. 83.2).

• Septo-optic dysplasia. Both unilateral and bilateral congenital IIIrd have been described.

• Rarities, e.g. congenital neurenteric cyst.

• Cyclic ocular motor palsy. This occurs following congenital or early onset acquired IIIrd nerve palsy. The child has a complete IIIrd nerve palsy but with superimposed episodic activity in IIIrd nerve innervated muscles. The muscles involved are usually the levator, which may elevate to a normal position or even retract, plus the superior and medial recti. A dilated pupil may constrict. These “spasms” of IIIrd nerve function are short-lived lasting 30 seconds to a minute and may be induced by contralateral eye movement or attempted fixation with the paretic eye, but may also occur spontaneously and in sleep. It is presumed that variable prenuclear activation of intact motor neurons is responsible for this phenomenon.

• Double elevator palsy. A hypotropia and deficit of elevation of an eye is due to an isolated palsy of the superior rectus and inferior oblique muscles. Differentiation from primary isolated ocular muscle fibrosis may require a forced duction test.

• Congenital medial rectus palsy with synergistic divergence. Isolated congenital medial rectus palsy is associated with divergence of both eyes on attempted adduction of the affected eye. This is probably a CCDD variant.

• Brown’s syndrome variant. Congenital failure of elevation in adduction may be associated with elevation of the ipsilateral lid on adduction which elevates further on gaze down and in. The lid movements are those of “misdirection regeneration” of the IIIrd nerve and this Brown’s syndrome variant may be due to IIIrd nerve pathology.

Fig. 83.1 Congenital left IIIrd nerve palsy. Axial T2-weighted scan shows superior vermis lesion (other presumed perinatal hypoxic ischemic lesions seen elsewhere).

Fig. 83.2 PHACES. Axial T2-weighted scan shows facial hemangiomata plus absent right internal carotid artery and dilated perforators in Sylvian fissures. Patient had congenital left IIIrd nerve palsy.

Management

Important steps in the management of congenital IIIrd nerve palsy are:

• Establishing the etiology if possible. This may be clear from the history or require investigation and neuroimaging.¹

• Advising the parents about the possible outcomes.

Vision

Amblyopia of the affected eye in unilateral cases is invariable. Patching of the uninvolved eye is essential but the visual outcome is usually poor. No binocular single vision (BSV) will develop.

Eye position and movement

Whether or not it will be possible to successfully align the affected eye with strabismus surgery will depend on the extent of the palsy. The outcome in a complete IIIrd nerve palsy is likely to be disappointing. The eye position should be corrected first before considering ptosis surgery. Ptosis surgery should not be undertaken unless corneal protection can be guaranteed.

Acquired IIIrd nerve palsy

Most cases are unilateral and likely to occur in a clinical context that helps establish the etiology.²

Trauma

The commonest cause is accidental closed head injury, e.g. in a road traffic accident. Isolated IIIrd nerve palsy is due to avulsion of the nerve rootlets from the brain stem. With basal skull fracture there are likely to be multiple cranial neuropathies.

IIIrd nerve palsy occurring after minor head trauma may indicate an underlying predisposing factor. IIIrd nerve palsy has been described after non-accidental injury in infants and following surgical trauma. Some spontaneous recovery for up to a year can be expected, often with misdirection–regeneration.

Infection

A. Bacterial meningitis. In neonates, due to group B streptococcal infection (also Escherichia coli/listeria with brain stem encephalitis), it may be complicated by unilateral or bilateral IIIrd; recovery is likely to be poor. Cerebral visual impairment is also common (see Chapter 56). IIIrd nerve palsy can also occur in infantile or childhood meningitis.

B. TB meningitis. This can present with or be complicated by unilateral or bilateral progressive IIIrd nerve palsy.

C. Para-infectious palsy. A presumed immune-mediated pathology is responsible for cases described after, for example, influenza vaccination or MMR (measles, mumps, rubella) vaccination. The condition can be recurrent.

D. Viral meningitis. Causal viruses include herpes simplex, Epstein-Barr virus, cytomegalovirus, and herpes zoster virus.

Tumor

Intracranial and intraorbital tumors can present with signs including a IIIrd nerve palsy, usually progressively worsening (Fig. 83.3). External compression, direct involvement of the nerve (e.g. by schwannoma), infiltration, or malignant meningitis may be responsible. Compression can be anywhere along the course of the nerve (e.g. brainstem glioma or parasellar tumor). Raised intracranial pressure may be a contributory or primary cause.

Fig. 83.3 Left intracavernous dermoid. Coronal T1-weighted scan; presented with progressive left IIIrd nerve palsy in an 8-year-old.

Additional neuro-ophthalmic signs should be sought to help localize the pathology: neuro-imaging is mandatory.¹

Rare causes

Vascular

A. Aneurysmal compression. This may occur in the first or second decade due to posterior communicating artery aneurysm: also (usually with a VIth nerve palsy) due to intracavernous internal carotid artery aneurysm in, for example, Loewys-Dietz syndrome (Fig. 83.4).

B. Vasculitis. Cases have been described secondary to Kawasaki’s disease with or without aseptic meningitis and raised intracranial pressure, also polyarteritis nodosa.

C. Vascular malformation. A hemorrhage in a brain stem cavernoma or other vascular malformation can present with a partial IIIrd nerve palsy.

Fig. 83.4 Loeys-Dietz syndrome. Axial T2-weighted scan showing large flow voids in bilateral internal carotid artery aneurysms. Patient has bilateral VIth nerve palsies.

Ophthalmoplegic migraine

This is a diagnosis of exclusion after full investigation.³ It cannot be made on clinical grounds alone. The syndrome is not certainly due to migraine. The diagnostic criteria are:

• Childhood onset IIIrd nerve palsy associated with headache, photophobia/photopsia, and nausea.

• Pupillary involvement and usually a complete palsy.

• Neuroimaging normal except for enlargement and gadolinium enhancement of the cisternal portion of the IIIrd nerve on MRI (not invariable).⁴ The cerebrospinal fluid (CSF) is normal.

• Steroid responsive (but self-limiting without treatment).

• Family history of migraine.

The differential diagnosis includes schwannoma, hemangioma, and lymphoma. The condition may be recurrent (Fig. 83.5).

Fig. 83.5 Recurrent right IIIrd nerve palsy × 3 from ages 5 to 9. Axial T1-weighted FS post gadolinium shows enhancing nodule on right IIIrd nerve. The scan also shows bilateral vestibular schwannomas indicating NF2.

It characteristically affects the IIIrd nerve but can affect the IVth or VIth.

Neuroma

IIIrd nerve neuroma producing a slowly progressive palsy can complicate NF2 or as an isolated tumor. The signs may fluctuate initially.

Inflammatory

Fascicular IIIrd nerve palsy may occur in ADEM (acute disseminated encephalomyelitis) and in childhood onset multiple sclerosis (MS).⁵

Idiopathic/cryptogenic

Despite full investigation, a small proportion of childhood onset IIIrd nerve palsies remain unexplained. It is important to be prepared to reinvestigate if new signs develop; ocular myasthenia, for example, can present as a unilateral pupil sparing IIIrd nerve palsy with negative antibodies and normal electromyography.⁶

Management

Establishing the etiology is the first priority. Treatable underlying pathology must be identified and managed appropriately.

In visually immature children, amblyopia is inevitable in the affected eye and should be managed in the conventional way.

At least 1 year from onset (e.g. of a traumatic palsy) should be allowed for spontaneous recovery before considering surgical treatment. Attempts to correct a neurogenic hypotropia by inferior rectus recession always lead to an abnormal recessed lower lid position: a better option is to move both horizontal muscles upwards with augmenting sutures if necessary.

IVth nerve palsy

Congenital palsy

This is the commonest congenital cranial nerve palsy and the commonest cause of hypertropia in children.⁷ It is usually unilateral.

The clinical signs are:

• An abnormal head posture (AHP) – possibly detectable from early infancy onwards. This consists of a tilt and turn of the head away from the side of the lesion (for differential diagnosis, see Box 83.1).⁸

• Without the AHP, a hypertropia of the affected eye which increases in adduction and reduces in abduction. This is associated with ipsilateral inferior oblique overaction/superior oblique underaction and contralateral superior rectus underaction/inferior rectus overaction.

• The Parks’ three step test is a useful way of identifying the primary underacting muscle (see Chapter 80).

Box 83.1

Differential diagnosis of a head tilt/turn in childhood

• Unilateral IVth nerve palsy

• Duane’s syndrome

• VIth nerve palsy

• Homonymous hemianopia

• Nystagmus with a null-zone

• Sternomastoid torticollis

Only gold members can continue reading. Log In or Register to continue

Related

Stay updated, free articles. Join our Telegram channel

Tags: Pediatric Ophthalmology and Strabismus

Jun 4, 2016 | Posted by admin in OPHTHALMOLOGY | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access