A patient with one peripheral nerve lesion may also have a second lesion elsewhere along the course of the nerve. Both lesions could contribute to the patient’s symptoms.
The nerve cell body produces material that is necessary for a normal function of the axon. These materials travel distally along the axon, breakdown products, and return in a proximal direction by the axonal transport mechanism. Disruption of the synthesis or blocking of the transport of these materials (antegrade/retrograde) increases sustainability of the axon to compression. Edema and impaired neural blood flow, neuropathy, diabetes, and decreased nerve elasticity such as in fibrosis.
Compression of the nerve at a point lowers the threshold for occurrence of compression neuropathy at another point distal or proximal at the same point by interfering with the axon transport mechanism. The outcome of surgical decompression may be disappointing unless both compression areas are treated. C5-C6 is the most common level that is affected in the neck. The EMG of the patient will show fibrillation or sharp waves in the biceps, extensor carpi radialis longus, and the extensor carpi radialis brevis muscles. This is different than the findings in carpal tunnel.
Common Double Crush Associations
- Cervical Root Compression and Carpal Tunnel Syndrome (Medial Nerve)
A lessor compression in median nerve at the carpal tunnel as seen in EMG (distal sensory latency) will produce symptoms when proximal cervical lesion is present. Coexisting cervical root compression is one of the main reasons for persistent residual symptoms following carpal tunnel relief. Physicians should not develop tunnel thinking, blaming tunnel syndrome when seeing patients, instead consider possibility of causes with a widener diagnostic approach which includes EMG and nerve studies from neck down. Persistence of the system of symptoms after initial treatment of nerve entrapment is an indication to search for another site of compression.
- Thoracic Outlet Syndrome and Carpal Tunnel Syndrome (Medial Nerve)
- Pronator Teres Syndrome and Carpal Tunnel Syndrome (Medial Nerve)
- Cervical Nerve Root Compression and Cubital Tunnel Syndrome (Ulnar Nerve)
- Thoracic Outlet Syndrome and Cubital Tunnel Syndrome
- Cubital Tunnel Syndrome and Guyon’s Cannel Syndrome (Ulnar Nerve)
The ulnar nerve enters the palm of the hand through the Guyon’s Canal.
Cervical Nerve Root Compression and Radial Tunnel Syndrome (Radial Nerve)
