Segmental H-reflex studies in upper and lower limbs of patients with radiculopathy.

The H-reflex was recorded from the flexor carpi radialis, vastus medialis, and soleus muscles in patients with radiculopathy at C7, L4, and S1 roots. Reflex parameters were compared to normal standards and correlated with other electrophysiologic (eg, electromyography) and clinical evaluations, as well as magnetic resonance imaging scan reports. The H-reflex had significantly smaller peak-to-peak amplitude and longer latency. The stimulus threshold for eliciting the reflexes was substantially higher than normal standards, and the reflex was polyphasic in most patients. A strong correlation was recorded between the pathologic changes in reflex parameters and electrophysiologic and clinical findings of different segmental lesions. Magnetic resonance imaging reports showed moderate correlation with the H-reflex changes. A test of specificity showed that soleus and vastus medialis H-reflexes were 100% specific for lumbosacral segments; flexor carpi radialis was 90% specific for cervical spinal segments. These results indicate that flexor carpi radialis, vastus medialis, and soleus H-reflexes are useful and valid methods for testing C7, L4, and S1 radiculopathy.