In the Hoffman reflex, what type of response is seen with flexion of the terminal phalanx of the thumb or index finger?

• A. Negative
• B. Positive
• C. Inconclusive
• D. Absent

Answer: (B)

The Hoffmann sign is about corticospinal tract excitability. When you flick the distal phalanx of the middle finger, a brisk flexion of the distal phalanx of the thumb or index finger is produced. That brisk, specific finger flexion is called a positive Hoffmann sign and indicates upper motor neuron (pyramidal) tract involvement. It reflects disinhibition and increased reflex activity in the spinal circuits controlled by the cortex, similar in concept to the Babinski sign in the leg. In healthy individuals the response may be absent or minimal, but a definite flexion of the thumb or index finger’s distal joint after flicking the middle finger is the positive finding.