H-reflex

H-reflex or Hoffmann's reflex is a reflex action in humans and other mammals, named after neurologist Paul Hoffmann. It is a test of nerve conduction, specifically the function of the nerve roots and peripheral nerves, and is used in the diagnosis of various neurological conditions.

Overview

The H-reflex is elicited by electrical stimulation of sensory fibers in a mixed nerve. The resulting electrical activity is recorded from the muscle innervated by the nerve. The H-reflex test is similar to the F-wave, but it is more selective and technically more demanding.

Procedure

The H-reflex is elicited by a stimulus to the sural nerve in the calf. The stimulus travels up the sensory fibers to the spinal cord, where it synapses with motor neurons that send an impulse back to the calf, causing a muscle contraction. The time it takes for the stimulus to travel up the sensory fibers and back down the motor fibers is measured as the H-reflex latency.

Clinical significance

The H-reflex is used in the diagnosis of neuropathy, radiculopathy, and spinal cord injury. It can also be used to assess the severity of these conditions and to monitor their progression. In addition, the H-reflex can be used to evaluate the effects of various treatments on nerve function.

See also

• Electromyography
• Nerve conduction study
• Neurophysiology