Conditions - Cranial Neuropathy and Brainstem Lesions Flashcards
What are the most common cranial neuropathies?
CNVI Abducent (most common)
CNIII Oculomotor
CNVII Facial
CNV Trigeminal
What are the most common polyneuropathies of the cranial nerves?
Oculomotor & Trochlear
Trigeminal & Facial
Trigeminal & Abducent
How are brainstem lesions classified?
Location
- midbrain / pons / medulla
Orientation
- medial / lateral
Origin
- intra-axial (originate in brainstem)
- extra-axial (original pathology external to brainstem)
Describe the condition of CN VI Abducent Neuropathy
SSX:
- medial deviation of affected eye (from unopposed action of medial rectus)
- diplopia (double vision)
Etiology:
- ischaemia most common
Describe the condition of CN VII Facial Neuropathy
SSX:
- ipsilateral SSX
- weakness / paralysis of muscles of facial expression
- eye unable to close (and subsequent eyelid irritation)
- decreased tear productiono
- drooling
Etiology:
- Bells Palsy common
Describe the condition of CN III Oculomotor Neuropathy
SSX:
- L and R oculomotor nuclei are located close together, so often both are affected
- visual and extra-ocular SSX
- paralysis of extraocular muscles
- diplopia (double visiono)
- ptsosis (drooping)
- dilated pupil
- diminished pupillary response
- no lens accomodation
Etiology:
- vascular insults of posterior cerebral or superior cerebellar artery
- trauma or lesion
Describe the condition of CN V Trigeminal Neuropathy
Anatomy:
- 4 nuclei (3 sensory & 1 motor)
- 3 divisions (V1, V2, V3)
- SSX vary depneding on nuclei / divisions affected
SSX:
- sensory SSX in face
- weakness / paralysis of mm mastication
- trigeminal neuralgia = severe and brief attacks of facial pain
- loss of corneal reflex
Describe the condition of trigeminal neuralgia
- can affect 1 or more branches of trigeminal nerve
- caused by compression of nerve, leads to demyelination and spontaneous nerve firings
SSX:
- brief attacks of severe facial pain
- trigger zone where palpation will trigger an attack
- usually asymptomatic between attacks
Describe the etiology and SSX of brainstem lesions
- usually caused by vascular insult (infarctions / haemorrhages), demyelinating disease or neoplasia
SSX:
- multiple cranial nerve involvement
- long tract signs (motor or sensory)
- crossed or alternating symptoms
- complex eye movement abnormalities
- vertigo / unsteadiness
- ataxia
- dysdiadochokinesia (unable to perform rapid alternating movements)
- nausea / vomiting
Which arteries supply different parts of the brainstem?
Midbrain
- basilar
- posterior cerebral
Pons
- basilar
- superior cerebellar
- anterior inferior cerebellar
Medulla
- vertebral
- posterior inferior cerebellar
- anterior and posterior spinal
Which parts of the brainstem are supplied by the basilar artery?
Midbrain and pons
Which parts of the brainstem are supplied by the posterior cerebral arteries?
Midbrain
Which parts of the brainstem are supplied by the superior cerebellar arteries?
Pons
Which parts of the brainstem are supplied by the vertebral arteries?
Medulla
Which parts of the brainstem are supplied by the anterior inferior cerebellar artery, and which by the posterior inferior cerebellar artery?
Anterior inferior cerebellar artery supplies pons
Posterior inferior cerbellar artery supplies medulla
Describe medial medullary syndrome
- occlusion of anterior spinal or vertebral arteries
damage caused to:
- medial lemniscus
- pyramids
- hypoglossal nucleus / nerve
SSX:
- ipsilalteral paralysis / atrophy of tongue caused by damage to hypoglossal nerve
- contralateral hemiparesis (weakness) caused by damage to pyramids
- contralateral loss of light touch, vibration, propioception caused by damage to medial lemniscus
Describe lateral medullary syndrome
- caused by occlusion of PICA or vertebral artery
damages:
- spinal trigeminal nucleus
- nucleus ambiguus
- spinothalamic tract
SSX:
- ipsilateral loss of pain and temperature sensory over face (damage to spinal trigeminal nucleus)
- ipsilateral paralysis of pharyngeal & laryngeal muscles
- contralteral loss of pain & temperature sensation over body (damage to spinothalamic tract)
- dysphagia (hoarseness)
- ipsilateral Horner’s Syndrome (damage to descending sympathetic fibres
What is Horner’s syndrome?
- caused by interruption to sympathetic supply
SSX:
- ptosis (drooping)
- mimosis (pupil constriction)
- enopthalmos (backward displacement of eyeball in orbit)
- facial anhidrosis (impaired ability to sweat on affected side of face)
Occlusion of the PICA and/or vertebral arteries is associated with which condition?
Lateral medullary syndrome
Occlusion of the anterior spinal and/or vertebral arteries is associated with which condition?
Medial medullary syndrome
