Presentation on theme: "Oculomotor nerve lesion Lesion results in: – Lateral squint & Diplopia (eye deviated laterally by the action of unopposed lateral rectus) – Ptosis (drooping."— Presentation transcript:
Oculomotor nerve lesion Lesion results in: – Lateral squint & Diplopia (eye deviated laterally by the action of unopposed lateral rectus) – Ptosis (drooping of upper eye lid) due to paralysis of levator palpebrae superioris. – Proptosis (forwards bulging of eye ball) due to relation of paralysis of extrinsic eye muscle.
-Pupil dilatation & loss of light reflex due to paralysis of constrictor pupillae. -Loss of accommodation (& convergence) reflex due to paralysis of ciliary muscle. - Impaired downward & outward movement of the eye ball on the damaged side. The preganglionic parasympathetic fibers run superficially in the nerve and are therefore the first axons to suffer when a nerve is affected by external pressure. Consequently, the first sign of compression of the occulomotor nerve is ipsilateral slowness of the pupillary response to light.
Trochlear nerve lesion Isolated trochlear nerve injury is rare. Lesion results in diplopia & inability to rotate the eye infero-laterally due to paralysis of the superior oblique muscle of the same side. The eye deviates; upward and slightly inward. Person has difficulty in walking downstairs. If you asking the patient to look downwards towards the opposite side of the lesion Leads to diploplia.
Abducent nerve palsy Lesion results in: Isolated abducent nerve injury is rare Isolated abducent nerve leads to medial squint with an inability to direct the affected eye laterally (due to unopposed action of the medial rectus) A nuclear lesion may also involve the nearby nucleus or axons of the facial nerve, causing paralysis of all the ipsilateral facial muscles.
Trigeminal nerve lesion Complete injury of the trigeminal nerve 1- Paralysis of the ipsilateral muscles of mastication & other muscles supplied by mandibular nerve. 2- Loss of sensation on the ipsilateral ½ of the face except the area over lateral ½ of the mandible. There is also unilateral loss of sensation of the anterior ½ of the scalp. Cornea, conjunctiva, mucosa of themouth & anterior 2/3 of the tongue. TRIGEMINAL NEURALGIA Inflammatory condition affecting one or more of the three divisions of trigeminal nerve. It is characterized by recurring of episodes of intense stabbing pain, radiating from angle of jaw along a branch of trigeminal nerve. Usually involves maxillary & mandibular nerves, sparing the ophthalmic division.
Facial nerve injuries Upper motor neuron (UMN) lesion of facial nerve: result from lesion of the pyramid tract above the level of facial nucleus (supranuclear lesion) It commonly occurs with capsular hemiplegia, There is hemiplegia accompanied by paralysis of lower ½ of the face of the opposite side of the capsular lesion. The upper part of the face is not affected asIt recieves corticobulbar from both sides.
While the lower ½ of facial nucleus receives corticobulbar pyramid fibers only from the opposite side. II- Lower motor neuron (LMN) lesion of facial nerve (Clinically called Bell s palsy): results from affection of the facial nucleus & facial nerve fibers. Manifested by Complete Paralysis of the facial muscles of the side of lesion. If the injury is proximal to geniculate ganglion: there is also loss of secrtion from lacrimal, nasal, buccal, sunmandibular & sublingual glands in addition to loss of taste sensation from the anterior 2/3 of the tongue on the affected side.
There is hyperacusis (increase sound perception ) due to paralysis of the stapedius muscle. If the injury is distal to the geniculate ganglion & above the origin of chorda tympani, glands will not affected.
Bell’s Palsy BELL’S (FACIAL) PALSY Lesion of facial nerve (below sytlomastoid foramen) results in paralysis of muscles of facial expression. It is of the lower motor neuron lesion type (whole face, at same side of lesion, is affected). Distortion of face : sagging of angle of mouth, dribbling of saliva, loss of facial expressions, loss of chewing, blowing, sucking, unable to show teeth or close eye.
Vestibular nerve lesion: leads to: 1- Vertigo: in the form of subjective feeling of rotaion of the individual or his surroundings. 2- Nystagmus: in the form of oscillating jerk movements of the eyes. 3- Nausea & vomiting. Cochlear nerve lesion: 1- complete loss of hearing of the same side of the lesion.
Lesion of glossopharyngeal nerve Isolated injury of the glossopharyngeal is rare. But its lesion result in loss of taste & general sensations from the posterior 1/3 of the tongue (corresponding side), anaesthesia of the pharynx, partial dryness of the mouth & loss of carotid sinus reflex. Vagus Nerve Lesion Unilateral Injury of the vagus nerve at the base of the skull result in paralysis of the muscles of the pharynx, palate & larynx on the same side, this leads to: 1- Dysphagis 2- Hoarseness of the voice 3- Loss of pharyngeal reflexes on the affected side & uvula deviation to the healthy side (palatal paralysis). Bilateral vagus injury at the base of the skull may be fatal as they lead to bilateral paralysis of the all laryngeal muscles lead to asphyxia unless emergency tracheostomy is done. Loss of vagal tone lead to tachycardia, dyspnea & loss of respiratory reflexes.
Lesion of spinal part of accessory nerve results into: Difficulty in swallowing and speech Inability to turn the head and raise the shoulder Winging of scapula
Lesion of the hypoglossal nerve Injury of the nerve & its nucleus (LMN paralysis) leads to paralysis of all the muscles of the tongue on the same side. The paralyzed tongue atrophy of the muscles & becomes shrunken and furrowed of its mucosa on the affected side 2- Difficulty in chewing and speech Unilateral lesion; the protruded tongue deviates to the affected side. Bilateral lesion; the person can’t protrude the tongue.
Lesion results in: visual field defects and loss of visual acuity, a defect of vision is called anopsia
Visual pathway Optic nerve Optic chiasma Optic radiation Lateral geniculate body Visual area Optic tract
1. Right-sided circumferential blindness due to retrobulbar neuritis. 2. Total blindness of the right eye due to lesion of right optic nerve. 3. Right nasal hemianopia due to partial lesion of right optic chiasm. 4. Bitemporal hemianopia due to a complete lesion of the optic chiasm. 5. Left temporal and right nasal hemianopias due to a lesion of the right optic tract. 6. Left temporal and right nasal hemianopia due to a lesion of the right optic radiation. 7. Left temporal and right nasal hemianopia due to a lesion of the right visual cortex.