Klumpke's paralysis: lower trunk injury and its effects
THE CONTEXT
Klumpke's paralysis follows injury to the lower trunk of the brachial plexus, involving mainly T1 and partly C8.
Mechanism and muscles affected
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Undue abduction of the arm can cause the injury, as when a person clutches something during a fall from a height; birth injury is another stated cause.
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Paralysis affects the intrinsic muscles of the hand associated with T1 and the ulnar flexors of the wrist and fingers associated with C8.
Hand deformity and sensory findings
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Complete claw hand results from unopposed action of the long flexors and extensors of the fingers.
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The metacarpophalangeal joints are hyperextended, while the interphalangeal joints are flexed.
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Cutaneous anaesthesia and analgesia affect a narrow zone along the ulnar border of the forearm and hand.
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The passage also lists loss of the biceps and supinator jerks.
Sympathetic involvement
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Injury to T1 proximal to the white ramus communicans to the first thoracic sympathetic ganglion may cause an associated sympathetic syndrome.
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The listed features are ptosis, miosis, absence of sweating, enophthalmos and loss of the ciliospinal reflex.
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These findings arise from injury to sympathetic fibres supplying the head and neck that leave the spinal cord through T1.
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The skin in the region of sensory loss becomes warmer because of arteriolar dilation and drier because sympathetic activity and sweating are lost.
Long-standing trophic changes
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Long-standing paralysis causes dry, scaly skin, easily cracked nails and atrophy of the pulp of the fingers.