H-reflex
Pronunciation: H-REE-fleks
A monosynaptic spinal reflex evoked by electrical stimulation, used to assess spinal cord function and nerve conduction integrity.
Full Definition
The H-reflex (Hoffmann reflex) is an electrically evoked spinal reflex that bypasses muscle spindles by directly stimulating sensory nerve fibers. The reflex arc involves stimulation of Ia afferent fibers, synaptic transmission in the spinal cord, and activation of alpha motor neurons. Most commonly tested in the soleus muscle via tibial nerve stimulation, the H-reflex provides information about spinal cord excitability, nerve conduction velocity, and neuromuscular function. H-reflex abnormalities can indicate peripheral neuropathy, radiculopathy, spinal cord pathology, or upper motor neuron dysfunction. The H-reflex is particularly useful for evaluating S1 nerve root function.
Usage
Usage note: Capitalize the 'H' and hyphenate (H-reflex) rather than using 'h reflex' or 'H reflex'.
In Context
- "The H-reflex was absent bilaterally, suggesting S1 radiculopathy or peripheral neuropathy." — Nerve conduction study report
- "H-reflex latencies were prolonged, consistent with the patient's clinical presentation of diabetic neuropathy." — Electrodiagnostic interpretation