Department of Neurosurgery

"Peripheral Nerves" are running in the periphery and connect the brain and the myelon with the extremities and the body surface. They can be temporarily or permanently damaged by trauma, strain, inflammation and tumors. Even after a complete transection peripheral nerves have the tendency to recover their function if the nerve ends are reconnected in time.

Usual signs of nerve injury are:

• Pain
• Numbness
• Pareses

As major nerves can be quite long, the symptoms might occur in the distant periphery and not only at the sight of injury. There are many common deformities like the “claw hand” (injury of the ulnar nerve), the “hand-of-benedict” (injury of the median nerve) or the “wrist-drop-hand” (injury of the radial nerve) that can occur whenever the corresponding nerve is impaired. Those symptoms are almost always associated with a loss of sensation in the respective skin area.

Beside injury and tumors nerve entrapment is a common cause of nerve impairment. Typical localizations are the carpal-tunnel-syndrom with nightly numbness of the first 3 fingers, caused by an entrapment of the median nerve at the wrist. Operative transection of the “retinaculum-flexorum-ligament” may ameliorate those symptoms immediately.

The cubital-tunnel-syndrom (CUTS) is caused by a narrowing of the ulnar nerve canal at the elbow, resulting in pain and numbness of the fourth and fifth finger, rarely in a weakness of the small hand muscles.

A narrowing of the peroneal tunnel can cause a weakness in the foot elevation, resulting in an irritating foot drop, and the rare tarsal tunnel syndrome mostly provokes pain in the sole of the foot. In a "thoracic-outlet-syndrome" the brachial nerve plexus is compressed, resulting in pain and numbness in the arm and hand mostly when the extremity is elevated.

Morton’s neuralgia – mostly seen in female patients – is the symptom of a compressed interdigital nerve and leads to pain between the 2^nd/3^rd or 3^rd/4^th toe. This syndrome is mostly caused by tight shoes and gets better when both broader shoes are used and the site is surgically decompressed.

Further diagnostic tools

Clinical examination by a specialist is crucial whenever a peripheral nerve injury or entrapment is assumed. Sometimes, infiltration with local anesthetics helps to isolate the site of irritation. Beyond clinical assessment, electromyography and nerve-conduction-velocity measurement can be performed in order to encircle the underlying cause. Also imaging techniques like MRI and sonography can be very helpful.

Operative treatment

Non-severe nerve irritation without transection can often be treated conservatively, but the treatment modality is dependent on the cause of the injury. If severe symptoms like pareses, numbness or pain persist under medical and physiotherapy, an operative approach is the therapy of choice.  Such surgery can either be performed in local or regional anesthesia or in general anesthesia. In an operative approach, nerve entrapments are decompressed and scar tissue resected to give the nerves space to function properly. Nerve tumors should be surgically resected in order to both avoid damage to the nerve by a growing tumor and to receive a histological assessment.

If a nerve is transected during an accident, both ends can either be adapted. If the gap between the ends is too big, a transplant from a tiny sensory nerve of the foot can be used to reconstruct motor and sensory function.

Prognosis

In general, the shorter the time of injury or entrapment, the better the function will recover. A too long conservative treatment e.g. in an injury of the brachial arm plexus may lead to an unfavorable outcome even if a surgical treatment is eventually chosen. As each nerve fiber usually grows with a speed of 1 mm/day, the motor and sensory recovery of extremities may last up to several months. Intensive physical therapy is crucial for a good result, and electrical stimulation may help the muscles to keep their shape until the nerve-connection is reestablished.