Neurology - Nerve Injury Flashcards
What is Bell’s palsy?
An acute, unilateral, idiopathic facial nerve (CN VII) paralysis.
Features of Bell’s palsy.
LMN facial nerve palsy - forehead affected.
Patients may also notice:
- post-auricular pain
- altered taste
- dry etes
- hyperacusis
Management of Bell’s palsy.
- oral prednisolone within 72 hours of presentation
- antivirals
Eye care:
- prescription of artificial tears
- close eye at night with microporous tape
Follow-up of Bell’s palsy.
Urgent referral to ENT if no improvement within 3 weeks.
Long-standing Bell’s palsy may require plastic surgery involvement.
Prognosis of Bell’s palsy.
Most people make a full recovery within 3-4 months.
If untreated, 15% of patients can have permanent moderate to severe weakness.
What is trigeminal neuralgia?
A pain syndrome characterised by severe unilateral pain.
Features of trigeminal neuralgia.
Unilateral facial pain:
- electric shock-like
- evoked by light touch
Causes of trigeminal neuralgia.
Most commonly idiopathic.
Compression by tumours or vascular issues may cause trigeminal neuralgia.
Red flag symptoms and signs suggestive of a serious underlying cause of trigeminal neuralgia.
- sensory changes
- deafness or other ear problems
- pain in opthalmic region only
- bilateral pain
- optic neuritis
- onset <40 years
Management of trigeminal neuralgia.
Carbamazepine first line.
Failure to respond to treatment or atypical features should prompt referral to neurology.
Features of vestibular schwannoma.
CN VIII: vertigo; unilateral sensorineural hearing loss; unilateral tinnitus.
CN V: absent corneal reflex.
CN VII: facial palsy.
Management of vestibular schwannoma.
Urgent referral to ENT - the tumour is often slow growing, benign and observed initially.
Investigations of vestibular schwannoma.
MRI of the cerebellopontine angle.
Audiometry.
Management of vestibular schwannoma.
- surgery
- radiotherapy
- observation
What is Erb’s palsy?
Damage to C5, C6 nerve roots caused by breech presentation.
Winged scapula; external rotation of shoulder and wrist flexion.
What is Klumpke’s palsy?
Damage to T1 nerve root caused by traction.
Loss of intrinsic hand muscles.
What is carpal tunnel syndrome?
Compression of the median nerve within the carpal tunnel.
Symptoms of carpal tunnel syndrome.
- paraesthesia in thumb, index and middle finger
- ascending symptoms
- shaking hand relieves sx
Examination of carpel tunnel syndrome.
Tinel’s sign: tapping causes paraesthesia.
Phalen’s sign: flexion of wrist causes paraesthesia.
Causes of carpal tunnel syndrome.
- idiopathic
- pregnancy
- oedema (e.g. heart failure)
- lunate fracture
- rheumatoid arthritis
Electrophysiology of carpal tunnel syndrome.
Motor and sensory prolongation of action potential in median nerve.
Can do nerve conduction studies.
Treatment of carpal tunnel syndrome.
Conservative:
- corticosteroid injection
- wrist splint at night
Surgical decompression if sx are severe (ie. flexor retinaculum division).
Divisions of the sciatic nerve.
MOA for common peroneal nerve injury.
Feature of common peroneal nerve injury.
FOOT DROP.
- weakness of foot dorsiflexion
- weakness of foot eversion
- weakness of extensor hallucis longus
- sensory loss over dorsum of foot and lower lateral leg
- wasting of anterior tibial and peroneal muscles
What nerve is affected in meralgia paraesthetica?
Lateral femoral cutaneous nerve.
Risk factors for meralgia paraesthetica.
- obesity
- pregnancy
- tense ascites
- trauma
- iatrogenic (ie. spinal surgery)
- gymnastics
- idiopathic
Symptoms of meralgia paraesthetica.
Upper lateral aspect of thigh:
- burning, tingling, shooting pain
- numbness
- deep muscle ache
- aggravated by standing; relieved by sitting
Signs of meralgia paraesthetica.
Reproduce sx by deep palpation below the ASIS.
Altered sensation over upper lateral aspect of thigh.
No motor weakness.
Path of the radial nerve.
- Lies posterior to the axillary artery.
- Enters the arm between the brachial artery and long head of triceps.
- Spirals around the radial groove in the proximal humerus.
- Descends down the lateral epicondyle of the humerus.
- Lies deeply between brachialis and brachioradialis.
Radial nerve innervation (m).
- triceps
- aconeus
- brachioradialis
- extensor carpi radialis
Radial nerve innervation - posterior interosseous branch (m).
- supinator
- extensor carpi ulnaris
- extensor digitorum
- extensor indicis
- extensor digiti minimi
- extensor pollicis longus and brevis
- abductor pollicus longus
Radial nerve innervation (s).
Features of damage to radial nerve.
- wrist drop
- sensory loss to dorsal aspect of the 1st and 2nd metacarpals
If damaged in the axilla, paralysis of triceps also occurs.
What is thoracic outlet syndrome?
Compression of:
- brachial plexus
- subclavian artery
- subclavian vein
at the site of the thoracic outlet.
Causes of thoracic outlet syndrome.
- neck trauma
- cervical rib
- scalene muscle hypertrophy
Presentation of neurogenic TOS.
- painless muscle wasting of hand muscles
- sensory symptoms
NB: autonomic nerve involvement causes cold hands, blanching and swelling.