# Clinical Cases: Upper Limb - Neurovasculature ## Case 1: Erb-Duchenne Palsy (Upper Brachial Plexus Injury) ### Clinical Image ![Brachial Plexus](case_01_image.jpg) *Source: [Wikimedia Commons - Brachial Plexus](https://commons.wikimedia.org/wiki/File:Brachial_plexus.svg) - Public Domain* ### Case Presentation A newborn male is delivered via vaginal delivery complicated by shoulder dystocia. Birth weight was 4,500 grams, and delivery required significant traction and maneuvers to release the impacted shoulder. Immediately after delivery, the pediatrician notes that the infant does not move his right arm. The arm is held in adduction and internal rotation at the shoulder, with the elbow extended, forearm pronated, and wrist flexed - the classic "waiter's tip" position. The infant withdraws to painful stimuli in the hand, and grasp reflex is intact. The Moro reflex is asymmetric, with the right arm failing to abduct and externally rotate. There is no clavicle fracture on palpation or chest X-ray. The infant is diagnosed with Erb-Duchenne palsy affecting the upper trunk of the brachial plexus (C5-C6). Physical therapy with passive range of motion exercises is initiated immediately to prevent contractures. At 3-month follow-up, the infant shows significant spontaneous recovery with return of biceps function. Complete recovery is expected by 6 months. ### Key Learning Points - The brachial plexus forms from ventral rami of C5-T1 and courses between the anterior and middle scalene muscles - Upper trunk (C5-C6) injury causes loss of shoulder abduction, external rotation, elbow flexion, and supination - "Waiter's tip" position: adducted/internally rotated shoulder, extended elbow, pronated forearm, flexed wrist - Obstetric brachial plexus injury occurs with shoulder dystocia and lateral neck flexion during delivery - Prognosis is generally good; spontaneous recovery occurs in majority of cases with intact hand function --- ## Case 2: Saturday Night Palsy (Radial Nerve Compression) ### Clinical Image ![Wrist Drop](case_02_image.jpg) *Source: [Wikimedia Commons - Wrist Drop](https://commons.wikimedia.org/wiki/File:Wrist_drop.jpg) - CC BY-SA 3.0* ### Case Presentation A 35-year-old man presents with inability to extend his right wrist and fingers that he noticed upon waking this morning. He admits to heavy alcohol consumption the night before and recalls falling asleep on a bench with his right arm draped over the backrest. He has no history of trauma. Physical examination reveals weakness of wrist extension (wrist drop), finger extension at the MCP joints, and thumb extension. He can extend his IP joints (medial bands of lumbricals intact). There is weakness of forearm supination with the elbow extended (brachioradialis), but supination with elbow flexed is intact (biceps). Elbow extension (triceps) is normal. Sensation is diminished over the dorsum of the hand and first web space (superficial radial nerve). Finger and thumb flexion are intact, and grip strength is normal. The diagnosis is radial nerve palsy from compression at the spiral groove of the humerus. He is given a wrist extension splint and reassured about the excellent prognosis. At 8-week follow-up, wrist extension has returned to full strength. ### Key Learning Points - The radial nerve (C5-T1) is the largest branch of the posterior cord and winds around the humeral shaft in the spiral groove - Prolonged compression against a hard surface compresses the nerve in the spiral groove (Saturday night palsy) - Clinical findings: wrist drop, finger drop, weak thumb extension, sensory loss over dorsal hand (superficial branch) - Triceps is usually spared because branches exit before the spiral groove - Finger IP extension is intact due to preserved lumbrical function (ulnar and median nerve) --- ## Case 3: Ulnar Nerve Entrapment at the Cubital Tunnel ### Clinical Image ![Cubital Tunnel Syndrome](case_03_image.jpg) *Source: [Wikimedia Commons - Ulnar Nerve](https://commons.wikimedia.org/wiki/File:Ulnar_nerve.png) - CC BY-SA 4.0* ### Case Presentation A 48-year-old accountant presents with 4 months of progressive numbness and tingling in his left small finger and the ulnar half of his ring finger. Symptoms are worse after prolonged elbow flexion, such as when talking on the phone or sleeping. He has noticed weakness when trying to spread his fingers apart and clumsiness with fine motor tasks like buttoning his shirt. Physical examination reveals decreased sensation in the ulnar 1.5 digits, both dorsally and volarly. There is visible atrophy of the first dorsal interosseous muscle. Weakness is noted with finger abduction (interossei), finger adduction, and thumb adduction (adductor pollicis). Froment's sign is positive - he flexes his thumb IP joint when attempting to grip paper between thumb and index finger (compensating with FPL due to adductor weakness). Tinel sign is positive at the cubital tunnel (posterior to the medial epicondyle). There is subluxation of the ulnar nerve over the medial epicondyle with elbow flexion. Nerve conduction studies confirm ulnar neuropathy at the elbow with slowing of conduction velocity across the cubital tunnel. He undergoes cubital tunnel release with anterior submuscular transposition. ### Key Learning Points - The ulnar nerve passes posterior to the medial epicondyle through the cubital tunnel (formed by medial epicondyle and olecranon) - The cubital tunnel is the most common site of ulnar nerve compression (second most common compression neuropathy after CTS) - Ulnar nerve supplies all interossei, medial two lumbricals, hypothenar muscles, and adductor pollicis - Sensory distribution: ulnar 1.5 digits (small finger + ulnar ring finger), both dorsal and volar surfaces - Froment's sign indicates adductor pollicis weakness; Wartenberg sign (small finger abduction) indicates interosseous weakness