Mononeuropathies Flashcards
Name the common nerves which are affected by neuropatheis?
Radial nerve Ulnar nerve Median nerve (and anterior interosseous nerve) Common peroneal nerve Femoral nerve
What are the main nerves given off by the brachial plexus?
Musclocutaneous nerve Axillary nerve Median Radial Ulnar
What is the most common cause of radial nerve palsy?
Saturday night palsy (pressure on the underside of the arm, causing entrapment of the nerve in the spiral groove)
What is the function of the radial nerve?
Motor - extends wrist and fingers - tennis backhand Sensory - area over the anatomical snuffbox
What are the presenting symptoms of a radial nerve palsy?
Wrist and finger drop
Numbness - usually painless
Describe the pattern of motor weakness in radial nerve palsy.
Wrist extension weakness - extensor carpi radialis longus
Finger extension weakness - extensor digitorum communis
Elbow flexion in mid-pronation - brachioradialis
What is the most common cause of ulnar nerve palsy?
Entrapment of the nerve at the ulnar groove (medial epicondyle of the humerus)
- caused by inflammation of lifestyle chanegs
What is the function of the ulnar nerve?
Motor - intrinsic muscles of the hand - some muscles of the forearm Sensory - medial aspect of the hand
What are the presenting symptoms of ulnar nerve palsy?
History of trauma at the elbow - repeated trauma causes permanent damage Sensory disturbance Weak grip Painless
Describe the pattern of motor weakness in ulnar nerve palsy.
Weakness in the following actions
- index finger abduction (1st dorsal interosseus)
- pinkie abduction (abductor digiti minimi)
- wrist flexion (flexor carpi ulnaris)
- thumb adduction (adductor policis)
What is the most common cause of medial nerve palsy?
Entrapment within the carpal tunnel at the wrist
- can be caused by inflammation and swelling of tendons within the tunnel
What is the function of the median nerve?
Sensory
- the most lateral 3.5 fingers on the palm
Motor
- flexors of the forearm
- LOAF (lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis)
What are the presenting symptoms of median nerve palsy?
Intermittent nocturnal pain
Numbness and tingling
Weak grip
Tinel’s sign
- lightly tapping the nerve to elicit tendernss and tingling over the wrist
Phalens test
- complete flexion of the wrist to elicit tingling and pain over the wrist
Which muscles display weakness in median nerve palsy?
Lumbicals (1 and 2) - flexion at the MCP joint Opponens pollicis - thumb opposition Abductor pollicis brevis - thumb abduction Flexor pollicis brevis - thumb flexion
What is the most common cause of anterior interosseous branch nerve palsy?
Trauma to the forearm
What is the function of the anterior interosseous branch?
This nerve branches off the median nerve in the forearm where it travels deeper to supply
- pronator quadratus (hand pronation)
- flexor pollicis longus (allows OK sign)
- lateral part of flexor digitorum profundus (thumb flexion)
What are the presenting symptoms of anterior interosseous nerve palsy?
History of forarm pain
Weak grip on keys
Tinels sign
Phalens test
Which muscles are weakened by an anterior interosseous nerve palsy?
Pronator quadratus - flexion at MCP joint is limited
Flexor pollicus longus - thumb flexion
Flexor digitorum profundus - thumb flexion
Give a brief description of the function of the nerve of the upper limb.
Radial nerve - tennis backhand - wrist and finger extension Median nerve - forearm flexors - LOAF Ulnar nerve - intrinsic muscles of the hand
Where is the lumbar plexus located?
Near iliopsoas
- damage to this muscles risks damage to the plexus
Name the large nerves of the hip (supply the thigh).
Femoral nerve
Sciatic nerve
Obturator nerve
Summarise the nerves of the thigh, and what they supply.
Femoral nerve - found in the front of the leg - supplies the quads (knee extension and hip flexion) Obturator nerve - found medially - hip adduction Sciatic nerve - found in the back of the leg - supplies the hamstrings (knee flexion, allowing running)
What is the most common cause of femoral nerve palsy?
Haemorrhage or trauma
What is the function of the femoral nerve?
Motor - knee extension - hip flexion Sensory - skin over the front and inner thigh, shin and arch of foot
What are the presenting symptoms of femoral nerve palsy?
Weakened quadriceps
Weakened hip flexion
Numbness on medial shin
Which muscles and actions are weakened in femoral nerve palsy?
Quadriceps - knee extension
Iliopsoas - hip flexion
Adductor magnus - hip adduction
Once it has entered the lower leg, what happens to the sciatic nerve?
At the knee, it splits into
- common pernoeal nerve (muscles in anterior and lateral leg compartments)
- tibial nerve (posterior leg compartment and sole of the foot)
Describe the pattern of distribution of the common pernoeal and tibial nerves?
Tibial - back of the leg
- motor: gastrocnemius and soleus muscles of the calf
Common peroneal - front of the leg
- motor: tibialis anterior and the peroneus muscles
- sensory: shin and dorsum of the foot
What is the most common cause of common perneal nerve palsy?
Entrapment at the fibular head.
What are the presenting symptoms of a common peroneal nerve palsy?
History of trauma, surgery or external compression Acute onset foot drop (plantarflexion) - stepage gait Sensory disturbance Painless
How can you tell the difference between common peroneal nerve palsy and L5 radiculopathy?
L5 radiculopathy and common peroneal nerve palsy both have sensory change down the lateral skin and foot dorsum
However L5 radiculopathy also has foot inversion
Which muscles and movements would be weakened in common peroneal nerve palsy?
Tibialis anterior - ankle dorsiflexion
Extensor hallucis longus - great toe extension
What is mononeuritis multiplex?
Simultaneous or sequential development of palsies of two or more nerves.
List some common causes of mononeuritis multiplex.
Diabetes Vascilitic - Churg Strauss Rheumatological - RA, lupus, Sjogrens syndrome Infective - Hep C, HIV Sarcoidosis Lymphoma
