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Home , Ulnar claw, Winged scapula, Wrist drop

QATAR MEDICAL JOURNAL VOL. 12 / NO. 1 / JUNE 2003

CONTINUOUS MEDICAL EDUCATION

Peripheral Nerve *Dr. Atlantic D'Souza and **Dr. A. A. Gehani Department of *Medicine and **CCSD, Hamad Medical Corporation Doha, Qatar

Introduction: Erb's-Duchenne (C 5,6) Peripheral nerve injuries are one of the usual spotter cases It's the most common birth , to the Erb's point caused in international exams. They are fun to diagnose and can be by displacement of the head to the opposite side and depression easily identified by knowing many of the characteristic signs of the on the same side. Eg: falls on the shoulder. The and tests. A few basic concepts in the anatomy , course and limb attitude is reflected by hanging limply by the side , being branches of the peripheral nerves makes it possible to diagnose medially rotated , the being pronated with flexed fin- the level of lesion with ease. gers and (waiter's tip hand)

Types: Klumpke's paralysis (C 8 & Tl) 1. Upper trunk lesions of the Its an injury to the lower trunk injury of the brachial plexus (Erb's Duchenne paralysis) usually caused by injury at birth or traction injury; as in exces- sive abduction of the arm Eg: grabbing a structure when falling 2. Klumpke's paralysis from a height. The 1st thoracic nerve is usually torn also giving 3. lesions rise to the Horner's syndrome. It is usually manifested by pa- 4. lesions ralysis of the muscles of the hand and development of a Claw hand. 5. lesions However the shoulder and movements are usually 6. lesions preserved and is a useful differentiating feature. 7. lesion

Brachial Plexus: nefve t0 $ubc,avUJS

lateral pectoral

thoracodorsal nerve

musculocutaneous nerve

axillary nerve long thoracic nerve radial nerve median nerve

Figure 1: Roots, trunks, divisions, s medial cutaneous nerve of the arm cords, and terminal branches of the * medial cutaneous nerve of the forearm brachial plexus.

Address for correspondence: Long thoracic nerve lesions (C5,6 & 7) Dr. Atlantic D'Souza Department of Medicine, Hamad Medical Corporation It results from radical mastectomy ,blows or surgical injury P. O. Box 3050, Doha, Qatar to the nerve in the and heavy lifting, leading to paralysis

66 Peripheral Nerve Injuries D'SouzaA., et. al.

of the and protrusion of the inferior extension but does not cause , because the extensors angle of the (). The patient also dem- are supplied prior to the division of radial nerve into Posterior onstrates difficulty in raising his arm over the head. The muscle interosseous and superficial Radial nerve. can be tested by asking the patient to push against a wall. Median Nerve Lesions C 5,6,7,8 & T1 Axillary nerve lesions (C 5, 6) It controls the coarse movements of the hand and grip, sup- It s usually caused by inferior plies all muscles of the forearm except dislocations of the , FCU and 1/2 FDP. In the hand it supplies the thenar muscle # surgical neck of & # & 1st and 2nd lumbricals. Causes of median nerve injuries in- scapula usually damaging the nerve clude: Supracondylar #'s of the humerus, wounds just proximal in the quadrangular space; leading to the flexor retinaculum, elbow dislocations, misplaced cubital to paralysis and rapid atrophy of the injection & . In lesions at/above cubital deltoid, loss of shoulder abduction, fossa, IP joint flexion of index is lost (Ochsner's clasp- loss of cutaneous sensation over the ing task) due to denervation of FDS. At the wrist: muscles of lower 1/2 of the deltoid muscle the are paralysed and wasted so that the emi- (regimental patch anesthesia) nence is flattened and the thumb is laterally rotated and adducted Radial Nerve Lesions C 5,6,7,8 & T1 (Ape like deformity), sensory loss of the hand occurs with spar- ing of the long flexors. Pincer action test: In lesion above mid It is motor & sensory to the dorsal compartment of the arm forearm, because of the sensory loss and paralysis of FPL & and forearm and divides in the elbow into the Superficial Ra- FDP to the index, patient is unable to pick up a pin placed over dial nerve ( sensory) and the Posterior Interosseous Nerve( a table with the thumb and index finger. Median nerve lesion motor). Lesion of the radial nerve causes sensory loss to the also causes sensory loss over the thumb and radial 2 _ dorsum of 2nd and 3rd Metacarpals^ and corresponding proxi- anteriorly and posteriorly as far as middle phalanx mal phalanges. It results from nerve injury in the spiral groove. Three conditions usually cause radial nerve lesions: # of midshaft Ulnar Nerve Lesions of the humerus, Crutch paralysis & Saturday night palsy . The function of the Ulnar nerve is mainly to control the fine When an injury is caused above the junction of upper and movements of the hand. Its lesion causes paralysis of the small middle third of the humerus the patient is unable to extend the muscles of the hand except for the muscles of the thenar emi- wrist and fingers (wrist drop) and the is paralysed. A nence, the 1st 2 lumbricals & FCU and FDP in the forearm. usual test is by asking the patient to extend his elbow against Here the patient is unable to adduct and abduct the fingers. Its resistance and palpating the triceps belly. A midshaft injury usually caused by injury to the nerve behind the medial epi- leads to a wrist drop with functional triceps and . condyle of the humerus, lesions where it lies in front of the Damage to the Posterior interosseous nerve causes weak finger flexor retinaculum at the wrist and in by com- and thumb extension & supination, radial deviation on wrist pression of an aponeurotic band that stretches over the medial epicondyle. When lesion occurs at elbow joint, there is pain over the medial aspect of the forearm and hand, weakness of the medial deep forearm muscles and loss of fine movements of the hand, FDP paralysis with hyperextension of Metacarpopha- langeal joints of little, ring and middle fingers. When lesions occur at the wrist the long medial flexors are spared, small muscles are paralysed but there may be preservation of sensa- it/ tion over the dorsal medial aspect of hand to the level of midphalanx of little and ring fingers (the dorsal cutaneous nerve iM arises 5cm above and may be spared). The ulnar nerve can be tested by flexing the fingers against resistance or resting the Sensory loss in a \ back of forearm and hand on a table and asking the patient to high radial nerve 1 flex and ulnar deviate the wrist. Interossei weakness can be tested lesion. (Signficant I I by asking the patient to grip a piece of paper between the fin- variability b/w § \ gers or by pinching a piece of paper between the thumb and patients) A N Wrist drop index. The Froment's sign which tests the adductor pollicis is also useful.

QATAR MEDICAL JOURNAL VOL. 12 / NO 1 / JUNE 2003 67 Peripheral Nerve Injuries D'SouzaA., et. al.

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Froment's sign Ulnar sensory loss in an ulnar lesion Proximal to the mid forearm Claw hand (Main-en-griffe)

Neurological Causes Non-neurological Causes 1. Median and ulnar nerve palsy Late and severe volkmann's ischemic 2. Lesion of the medial cord of the Advanced and untreated R.A brachial plexus 3. Klumpke's paralysis Neglected suppurative tenosynovitis of the ulnar bursa 4. Anterior. Polimyelitis 5. Syringomyelia 6. Progressive muscular atrophy 7. Polyneuritis 8. Amyotrophic lateral sclerosis

Claw hand paralysis of the small muscles of the hand lesions occur at the level of elbow joint or above additional pa- (lumbricals and interossei), most prominent in the 4th and 5th ralysis of the action of the flexor digitorum profundus on the fingers & hyperextension of the metacarpophalangeal joints little and ring fingers prevents flexion at Interphalangeal joints An hand caused by a lesion at the wrist is asso- and produces an ulnar nerve paradox i.e the higher the lesion ciated only with clawing of the little and ring fingers as the rest the less the deformity. of the hand is supplied by the median nerve. When ulnar nerve

B Ulnar claw hand

68 QATAR MEDICAL JOURNAL VOL. 12 / NO. 1 / JUNE 2003