3rd, 4th & 6th Cranial Nerve Palsies

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III, IV, VI Cranial Nerve Palsies:

III, IV, VI Cranial Nerve Palsies Sridevi Rajeeve 2008 batch 1

III Cranial Nerve (Oculomotor nerve):

Oculomotor nerve innervations : Superior rectus Inferior rectus Medial rectus, Inferior oblique Levator palpebrae superioris Ciliary muscle Iris sphincter (Constrictor pupillae) III Cranial Nerve ( Oculomotor nerve)

III cranial nerve Palsy Significance of its Anatomy and relations :

The anatomy and its relations of the various portions of the third cranial nerve accounts for the clinical features of third cranial nerve palsy. III cranial nerve Palsy Significance of its Anatomy and relations

Anatomy and its relations of III cranial nerve (in brief) :

1) Nuclear portion : situated in the midbrain. 2)Fascicular portion : situated ventrally to the mid brain 3)Fascicular subarachnoid portion : situated anterior to the midbrain and in close proximity to the posterior communicating artery. 4) Fascicular cavernous sinus portion : Runs through the lateral wall of the cavernous sinus and enters the cavernous sinus 5) Fascicular orbital portion : situated in the posterior part of the orbit Anatomy and its relations of III cranial nerve (in brief)

Clinical significance…:

Clinical significance… III portion: Fascicular subarachnoid portion : Clinical significance : Berry aneurysm at the junction between the posterior communicating artery and the internal carotid artery. IV Portion: Fascicular cavernous sinus portion : Clinical significance : Masses invading the cavernous sinus are likely to cause third cranial nerve dysfunction

Aetiology:

Aetiology direct trauma , demyelinating diseases (e.g., multiple sclerosis ) increased intracranial pressure (leading to uncal herniation ) due to a space-occupying lesion (e.g., brain cancer ) or a spontaneous subarachnoid haemorrhage (e.g., berry aneurysm ), and microvascular disease, e.g., diabetes.

Clinical Features of IIIrd Nerve Palsy:

Symptoms : 1 ) Diplopia from misalignment of the visual axes 2 ) Symptomatic Glare in bright light (if the ptotic lid does not cover the pupil ) Findings : 1) Involved eye usually is deviated down and out ( infraducted , abducted) 2 ) Ptosis (differentiated from myasthenia gravis by TENSILLON TEST) 3) Pupillary Dilatation 4) Paralysis of Accommodation causes blurred vision for near objects Clinical Features of IIIrd Nerve Palsy

Photograph: Patient with third cranial nerve palsy due to left posterior communicating artery aneurysm:

Photograph : Patient with third cranial nerve palsy due to left posterior communicating artery aneurysm

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Treatment 1) Symptomatic cases can be treated with Strabismus surgery , 2) Surgical correction of Ptosis: Ptosis surgery

IV Cranial Nerve (Trochlear) palsy :

Innervation : the Superior oblique muscle Physiological Actions : 1) Primarily Intort the eye (such that the top of the eye rolls toward the nose), 2)Secondary actions of depression ( down gaze ) and abduction ( looking away from the nose ). Clinical features in Palsy : 1 ) The affected eye Extorts , 2) Deviate Upwards ( H ypertropia ), 3 ) Drift Inward . IV Cranial Nerve ( Trochlear ) palsy

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Aetiologyof IV Cranial Nerve Palsy: 1) Usually neurogenic 2) Dysgenesis of the IV CN nucleus or nerve, 3) Clinically similar palsy may result from absence or mechanical dysfunction (e.g., abnormal laxity) of the superior oblique tendon

Clinical Features of IV Cranial nerve Palsy :

Clinical Features of IV Cranial nerve Palsy Congenital IV cranial nerve palsy : 1) It may not become symptomatic until later childhood or adulthood. 2) Young children adopt a compensatory position head tilt ( T orticollis ) in order to compensate for the underacting superior oblique muscle (towards contralateral side) 3) Facial asymmetry due to chronic head tilt. 4) Vertical diplopia

IV cranial Nerve palsy- Clinical features :

1) Lack of subjective symptoms of torsion (Torsion -rotation of vertical corneal meridians) 2) Diplopia - following Cataract surgery - manifest transiently during pregnancy 3) Neck Pain after years of head tilting. IV cranial Nerve palsy- Clinical features

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Treatment Symptomatic cases can be treated with Strabismus surgery Prism lenses set to make minor optical changes in the vertical alignment may be prescribed instead of or after surgery to fine-tune the correction.

VI CRANIAL NERVE(ABDUCENT) PALSY :

Innervation : Lateral rectus muscle Physiological action: Abduction Palsy causes: 1. Horizontal double vision 2. Convergent Strabismus ( Esotropia ) VI CRANIAL NERVE(ABDUCENT) PALSY

Aetiology: :

Increased intra-cranial tension Diabetes mellitus Trauma Brain stem hemorrhage/infarction Tumour Meningitis Aneurysms(basilar artery) Cerebello -Pontine angle tumour Orbital tumour Gradenigo’s syndrome ( otorrhoea–diploplia-retroorbital pain) Aetiology :

Localizing Signs :

1. Brainstem Isolated lesions of the VI nerve nucleus will not give rise to an isolated VIth neve palsy because paramedian pontine reticular formation fibers pass through the nucleus to the opposite IIIrd nerve nucleus. Thus, a nuclear lesion will give rise to an ipsilateral gaze palsy. In addition, fibers of the seventh cranial nerve wrap around the VIth nerve nucleus, and, if this is also affected, a VIth nerve palsy with ipsilateral facial palsy will result. In Millard Gubler syndrome , a unilateral softening of the brain tissue arising from obstruction of the blood vessels of the pons involving sixth and seventh cranial nerves and the corticospinal tract, the VIth nerve palsy and ipsilateral facial paresis occur with a contralateral hemiparesis . [4] . Foville's syndrome can also arise as a result of brainstem lesions which affect Vth , VIth and VIIth cranial nerves. 2. Sub arachnoid space As the VIth nerve passes through this space it lies adjacent to anterior inferior and posterior inferior cerebellar and basilar arteries and is therefore vulnerable to compression against the clivus . Typically palsies caused in this way will be associated with signs and symptoms of headache and/or a rise in ICP. 3. Petrous Apex The nerve passes adjacent to the mastoid sinus and is vulnerable to mastoiditis , leading to inflammation of the meninges , which can give rise to Gradenigo's syndrome . This condition results in a VIth nerve palsy with an associated reduction in hearing ipsilaterally , plus facial pain and paralysis, and photophobia. Similar symptoms can also occur secondary to petrous fractures or to nasopharyngeal tumours . 4. Cavernous sinus/Superior orbital fissure The nerve runs in the sinus body adjacent to the internal carotid artery and oculo -sympathetic fibres responsible for pupil control, thus, lesions here might be associated with pupillary dysfunctions such as Horner's syndrome . In addition, III, IV, V1, and V2 involvement might also indicate a sinus lesion as all run toward the orbit in the sinus wall. Lesions in this area can arise as a result of vascular problems, inflammation, metastatic carcinomas and primary meningiomas . 5. Orbit The VIth nerve's course is short and lesions in the orbit rarely give rise to isolated VIth nerve palsies, but more typically involve one or more of the other extraocular muscle groups. Localizing Signs

Management:

The first aims of management should be to identify and treat the cause of the condition, where this is possible, and to relieve the patient's symptoms, where present. In children, who rarely appreciate diplopia , the aim will be to maintain binocular vision and, thus, promote proper visual development. Thereafter, a period of observation of around 9 to 12 months is appropriate before any further intervention, as some palsies will recover without the need for surgery . Management

PowerPoint Presentation:

Fresnel prisms : slim flexible plastic prisms can be attached to the patient's glasses, or to plano glasses if the patient has no refractive error, and serve to compensate for the inward misalignment of the affected eye. Use of Botulinum helps to prevent the contracture of the medial rectus which might result from its acting unopposed for a long period. reduces the size of the deviation temporarily it might allow prismatic correction to be used where this was not previously possible removes the pull of the medial rectus it may serve to reveal whether the palsy is partial or complete by allowing any residual movement capability of the lateral rectus to operate Vertical muscle transposition procedures such as Jensen's, Hummelheim's or whole muscle transposition

Investigative tests to be done.. :

III NERVE : Eye Movements , Eyelid Movements, Pupil: Size, Symmetry, Reactions . IV and VI NERVE : Eye Movements V NERVE : Sensation to face Corneal reflex Jaw movements Investigative tests to be done..

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