Brachial Plexus Injuries
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Direct answer
Waiter's tip versus claw hand is the shorthand the exam wants: an upper plexus injury (Erb's palsy, C5-C6, from shoulder dystocia or downward traction) produces an adducted, internally rotated arm with extended elbow and pronated forearm — the posture of a waiter hinting for a tip — while a lower injury (Klumpke's palsy, C8-T1, from forced abduction) produces a claw hand with intrinsic wasting and, when T1 roots avulse, an ipsilateral Horner syndrome. The most consequential distinction in adult injuries is pre-ganglionic (root avulsion — irreparable by grafting, with preserved sensory nerve action potentials in an anaesthetic dermatome, pseudomeningocoele on myelography) versus post-ganglionic (rupture — repairable by graft or transfer). Birth palsies occur in roughly 0.4-2 per 1000 deliveries; most recover spontaneously, and absent biceps recovery by three months flags surgical referral. Adult traction injuries from two-wheeler accidents are explored within weeks to months by pattern, with nerve transfers — Oberlin for elbow flexion, spinal accessory to suprascapular — now central to reconstruction.
What you must remember
- Root values map the posture: C5-C6 (Erb) — shoulder abductors, external rotators and elbow flexors paralysed, giving waiter's tip; C8-T1 (Klumpke) — intrinsic minus, claw hand, Horner when T1 avulsed; C7 loss adds extension weakness; total palsy is a flail anaesthetic limb.
- Pre-ganglionic markers: Horner syndrome, preserved sensory nerve action potential from an anaesthetic hand (dorsal root ganglion intact but disconnected), pseudomeningocoele on CT or MR myelography, phrenic palsy, intractable deafferentation pain — these roots cannot be grafted.
- Post-ganglionic markers: conduction absent across the lesion with distal degeneration and normal myelography; ruptures repaired with sural cable grafts or excised neuromas-in-continuity and grafted.
- Birth palsy timeline: most recover spontaneously; biceps contraction by 3 months predicts good recovery, and its absence is the referral trigger for microsurgery.
- Adult management clock: clean laceration — immediate repair; closed traction — serial assessment with exploration around 3-6 months if plateaued, earlier for complete palsy with pre-ganglionic signs.
- Priorities of reconstruction: elbow flexion first, then shoulder stability and abduction, wrist and finger extension, lastly intrinsic function; short-distance transfers (Oberlin) beat long grafts by reinnervating in months.
Two very different referrals
A 3.5 kg newborn after shoulder dystocia holds the right arm adducted and internally rotated, elbow extended, forearm pronated, hand moving — classic Erb's palsy, C5-C6, no Horner syndrome. Management is physiotherapy to maintain joint range, parental teaching of exercises, and monthly review of biceps: by three months this infant visibly flexes the elbow against gravity, so surgery is off the table and prognosis good — the majority follow this path. Had biceps stayed silent at three to four months with a complete deficit, referral for exploration and grafting or transfer follows.
The second referral is a 24-year-old motorcyclist with a flail, anaesthetic arm after a high-speed fall, Horner syndrome on the right, an elevated hemidiaphragm, and MR myelography showing C5-C7 pseudomeningocoeles — pre-ganglionic avulsion of the upper roots, not a repairable rupture. The plan becomes transfer surgery: spinal accessory to suprascapular for shoulder stability, Oberlin transfer for elbow flexion, intercostal or pectoral donations for the long game; years-late presentations need tendon transfers, shoulder arthrodesis, or free functioning gracilis transfer.
Where students slip
Anatomically, candidates mix the traction directions: shoulder dystocia stretches C5-C6 by pulling head from shoulder, while a grasping fall hyperabducts and stretches C8-T1 — matching mechanism to root level is half the marks. "Horner means worse prognosis" is quoted without the reason: it marks T1 avulsion, which is pre-ganglionic and ungraftable. Temporally, the birth-palsy number that decides management is biceps by three months, and the adult exploration window of three to six months for closed injuries is the other probed date. In Indian conditions, adult plexus injuries cluster around two-wheeler and agricultural machinery trauma, patients present months late after traditional massage and splinting, and microsurgical expertise is concentrated in few centres — so honest counselling about what late presentation forfeits is part of the practical answer.
Frequently asked questions
What posture defines Erb's palsy and which roots are involved?
C5-C6 injury gives the waiter's tip — shoulder adduction and internal rotation, elbow extension, forearm pronation, wrist flexion — classically from shoulder dystocia traction.
What marks a pre-ganglionic avulsion injury?
Horner syndrome, preserved sensory nerve action potentials from an anaesthetic dermatome, pseudomeningocoele on myelography, phrenic palsy and severe deafferentation pain — findings that rule out useful graft repair.
When is birth brachial palsy referred for surgery?
When biceps function has not returned by about three months, since early elbow flexion recovery is the best predictor of spontaneous outcome.
What is the Oberlin transfer?
One fascicle of the ulnar nerve transferred to the biceps branch of the musculocutaneous nerve to restore elbow flexion — short distance, reinnervation typically within months.
Why is elbow flexion the first reconstruction priority?
It positions the hand in space and enables most daily functions; without it even a sensate hand is functionally marooned, so grafts and transfers are budgeted toward it first.