Neuropathies Flashcards
What is mononeuritis multiplex? What are the causes?
Dysfunction of 2+ peripheral nerves
Most common: DM
-HIV, amyloidosis, sarcoid
Describe the presentation of an ulnar nerve palsy
Partial claw hand
- Flexion of the intrinsic muscles of the hand
- Hypothenar wasting
- Loss of sensation to medial 1 1/2 fingers
What is the most common cause of an ulnar nerve palsy?
Elbow trauma eg. supracondylar fracture
What are the ulnar nerve roots?
C7-T1
Describe the presentation of a median nerve palsy
Carpal tunnel syndrome
- Thenar muscle wasting
- Parasthesia/anaesthesia of the palmar side of lateral 3 1/2 digits and palm
- LLOAF muscle weakness
- Tinel’s and Phalen’s test +ve
What are the causes of median nerve palsy?
Carpal tunnel syndrome -Pregnancy -High BMI -Occupational factors -Acromegaly Trauma
What are the median nerve roots?
C6-T1
Describe the presentation of radial nerve palsy
Wrist drop
- Weakness of the extensor muscles of the forearm and hand
- Parasthesia/anaesthesia of the dorsal thumb
What are the radial nerve roots?
C5-T1
What are the causes of radial nerve palsy?
Trauma
- Wrist fracture
- Fracture of the humeral shaft
Describe the presentation of Erb’s palsy. What are the affected nerves?
Caused by lesion of upper branch of brachial plexus (C5-6)
- Internally rotated shoulder
- Flexed wrist (waiter’s tip)
- Often present from birth
Describe the presentation Klumpke’s palsy. What are the affected nerves?
Caused by a lesion of the lower branch of the brachial plexus (C8-T1)
-Claw hand
What is the name of palsy of the lateral cutaneous nerve of the thigh?
Meralgia parasthetica
What are the nerve roots of the sciatic nerve?
L4-S3
What are the nerve roots of the common peroneal nerve?
L4-S2
What are the nerve roots of the tibial nerve?
L4-S3
Describe the presentation of a tibial nerve palsy
Inability to tip-toe walk
- Weakness of ankle plantarflexion and inversion, digit flexion
- Parasthesia/anaesthesia of the posterolateral leg, lateral foot and sole of the foot
Describe the presentation of a common peroneal nerve palsy
Footdrop- inability to heel-walk
- Weakness of ankle dorsiflexion and eversion, digit extension
- Parathesia/anaesthesia of the lateral leg, dorsum of foot
What are some causes of common peroneal nerve palsy?
- Fracture of fibula
- Tight plaster cast
Describe the presentation of sciatic nerve lesion
- Weakness of knee flexion
- Weakness of ankle and digits movements
- Reduced sensation to posterolateral leg and foot
What are the nerve roots of the femoral nerve?
L2-L4
Describe the dermatomes of the lower limb
L1: groin L2: anterolateral thigh L3: medial thigh to the knee L4: medial leg L5: big toe/ anterior leg S1: small toe and heel S2: posterior leg S3: buttock
Describe the dermatomes of the upper limb
C5: upper shoulder (deltoid), lateral arm C6: lateral forearm, thumb C7: middle finger C8: pinky finger, medial forearm T1: medial arm
Describe the presentation of Bell’s palsy
7th/facial nerve palsy
- Sudden onset unilateral weakness of the facial muscles, non-forehead sparing
- Altered taste sensation
- Hyperacusis, otalgia
What are the differentials for Bell’s palsy?
- Lyme disease
- Ramsay Hunt syndrome
- UMN: stroke
- Neoplasms
Describe the diagnostic process for suspected Bell’s palsy
- History suggestive
- Examination: full cranial nerves, otoscopy
- Consider: Lyme serology, EMG, MRI
Describe the management of Bell’s palsy
Conservative: corneal protection (glasses, drops)
Medical: corticosteroids within 72 hours of onset
-60mg PO for 5/7 -> taper
Surgical: decompression in severe cases
What is the prognosis of Bell’s palsy? Name some complications
70% fully recover within several months
Improved with steroids
Complications: corneal abrasion, keratoconjunctivitis sicca, crocodile tears (eat -> tears), synkinesis (blink -> upturn mouth)
Describe the presentation of Ramsay Hunt syndrome
Otalgia followed by facial weakness, dysgeusia, hyperacusis (very similar to Bell’s palsy)
Presence of vesicles on the TM/ear canal, hard palate
-May also have 8th nerve involvement
Describe the treatment of Ramsay Hunt syndrome
Valaciclovir and prednisolone
Name some causes of bilateral polyneuropathy
- DM
- Inflammatory: GBS
- Infectious: HIV
- Toxins, medications, alcohol
- Metabolic: B12 deficiency, hypothyroidism
- Vascular
What investigations would you consider for polyneuropathy?
- History and exam
- Bloods: FBC, CRP and ESR, U+Es, LFTs, HbA1c, TFTs, B12, HIV
- Special tests: EMG, NCS
Describe the presentation of diabetic neuropathy
- Sensory neuropathy in a glove + stocking distribution
- Reduced/absent deep tendon reflexes
- Foot drop, muscle weakness
- Joint deformity
Describe the presentation of GBS
- Acute onset symmetrical polyneuropathy
- Distal sensory abnormality and progressive proximal ascending muscle weakness (LMN)
- Following GI/resp infection
- Peaking within 2 weeks, resolving within months
Describe the diagnostic process in suspected GBS
- History and examination suggestive
- Bloods: general screen, anti-ganglioside antibodies, LFTs
- NCS
- LP for CSF analysis (raised protein w normal cell count)
- Spirometry 6 hourly initially to determine ICU need
- Consider MRI if unclear or ?spinal cord lesion
Describe the management of GBS
Supportive: -Analgesia -Airway -Antithrombotic -Autonomic support IVIG or plasma exchange Rehabilitation
What is Charcot Marie Tooth disease?
A group of hereditary peripheral neuropathies
Describe the presentastion of CMT
- Onset during puberty
- Mixed motor and sensory polyneuropathy
- Motor: weakness of anterior leg muscles: foot drop, champagne bottle legs, pes cavus, toe clawing. Absent ankle jerks
- Sensory: stocking pattern loss
What are the investigations for CMT?
- NCS
- Genetic testing
What is the use of nerve conduction studies?
- To diagnose peripheral neuropathies
- Can differentiate between sensory and motor neuropathy
