A 24-year-old patient presents with weakness of all intrinsic hand muscles (both thenar and hypothenar), loss of sensation over the entire hand and medial forearm, and no Horner's syndrome. This pattern of deficit is most consistent with which level of injury?

• A Combined complete median and ulnar nerve lesion at the wrist
• B Medial cord of the brachial plexus injury
• C T1 nerve root avulsion (preganglionic)
• D Lower trunk (C8-T1) injury of the brachial plexus ✓

Explanation

Lower trunk (C8-T1) injury (Klumpke's type) affects all intrinsic hand muscles (both median-innervated thenar and ulnar-innervated hypothenar and interossei), causing total claw hand. Sensory loss covers the medial forearm and medial two fingers (medial cutaneous nerve of forearm C8-T1). Absence of Horner's syndrome suggests the T1 sympathetic contribution is intact (postganglionic T1 lesion affecting the rami after sympathetic outflow has left). Medial cord injury would spare C8 root-specific muscles. Combined median+ulnar wrist lesion would spare medial forearm sensation.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.