Nerve Lesions Flashcards
How does carpal tunnel syndrome occur?
Results from pressure and compression on the median nerve as it passes through the carpal tunnel in the wrist
What is the compression in carpal tunnel syndrome usually the result of?
Inflammation of nearby tendons and tissues = oedema
What is carpal tunnel syndrome associated with?
- Hypothyroidism
- Diabetes mellitus
- Pregnancy (third trimester)
- Amyloidosis including in dialysis patients
- Obesity
- Rheumatoid arthritis - joint inflammation
- Acromegaly
Is carpal tunnel syndrome more common in men or women and why?
It is more common in women as they have narrower wrists but similar sized tendons
How do the symptoms in carpal tunnel syndrome usually start?
Aching pain in the hand and arm (especially at NIGHT)
What can the symptoms of carpal tunnel syndrome lead to?
Paresthesia (tingling or prickling) in thumb, index, middle & 1/2 ring fingers + palm (median nerve distribution)
What can often relive the paresthesia caused by carpal tunnel syndrome?
Relieved by dangling the hand over the edge of the bed - “wake and shake”
Apart from pain and paresthesia what other symptoms can carpal tunnel syndrome cause?
- Sensory loss and weakness of abductor pollicis brevis (thumb abductor) +/- wasting of the thenar eminence (muscles at the base of thumb)
- Clumsiness with fiddly tasks
- Light touch, 2-point discrimination and sweating may be impaired
What would you see on an Electromyography (EMG) in someone with carpal tunnel syndrome?
- See slowing of conduction velocity in the median sensory nerves across the carpal tunnel
- Prolongation of the median distal motor latency
- Helps to confirm lesion site and severity
What is the Phalens test?
Patient can only maximally flex wrist for 1 minute and will produce symptoms of carpal tunnel.
What is the tinsel test?
Tapping on the nerve at the wrist induces tingling - but non-specific.
What symptoms would be present in a lesion in the oculomotor nerve (CNIII)?
- Ptosis - dropping eyelids
- Fixed dilated pupil - loss of PARASYMPATHETIC outflow from EDINGER WESTPHAL NUCLEUS which supply pupillary sphincter and ciliary bodies - lens accommodation
- Eye down and out
What symptoms would be present in a lesion in the trochlear nerve (CNIV)?
A head tilt to correct the extortion that results in diplopia on looking down e.g. walking downstairs
What does the trochlear nerve do?
Innervates superior oblique muscle
What does the abducens nerve do?
Innervates the lateral rectus
What are the symptoms of trigeminal nerve palsy?
- Jaw deviates to side of lesion
- Loss of corneal reflex
What are the symptoms of facial nerve palsy?
Facial droop and weakness
What are some causes of facial nerve palsy?
- Bells palsy (most common) lesion of the facial nerve
- Fractures of the petrous bones
- Middle ear infections
- Inflammation of the parotid gland - which facial nerve passes through
What are the symptoms of a vestibulocochlear nerve palsy?
- Hearing impairment
- Vertigo and lack of balance
What are the causes of a vestibulocochlear nerve palsy?
- Tumour (in the internal acoustic meatus - will press on the vestibulocochlear & facial nerve)
- Skull fracture
- Toxic drug effects
- Ear infections
What are the symptoms of a CN 9 (Glossopharyngeal) & CN 10 (Vagus) palsy?
- Gag reflex issues
- Swallowing issues
- Vocal issues
- Caused by a jugular foramen lesion
What are the overall symptoms of Brown-Sequard syndrome?
- Ipsilateral loss of; proprioception, motor & fine touch
- Contralateral loss of; pain, temperature & crude touch
What is paraplegia?
Paralysis of BOTH LEGS ALWAYS caused by spinal cord lesion
What is hemiplegia?
Paralysis of ONE SIDE of body caused by lesion of the brain
What are the signs of an UMN lesion?
- Increased muscle tone - SPASTICITY: - Velocity dependent and non-uniform i.e. the faster you move the patients muscle, the greater the resistance, until it finally gives way in a clasp-knife manner
- Weakness: - Flexors are generally weaker than extensors in legs and reverse in arms
- Increased reflexes, they are brisk - HYPERREFLEXIA
What are the signs of a LMN lesion?
- Decreased muscle tone - WASTING (atrophy) +/- FASCICULATIONS (spontaneous involuntary twitching)
- Weakness that corresponds to those muscles supplied by the involved cord segment, nerve root, part of plexus or peripheral nerve
- Reflexes are reduced or absent - hyporeflexia