Numbness and tingling (paresthesia) are abnormal sensations that can be felt anywhere in the body. Most commonly, numbness or tingling can be perceived in a hand, arm, leg or foot. Carpal tunnel syndrome is an example of a condition with paresthesia in one or both hands. Carpal tunnel usually presents with a pins and needles sensation, and is diagnosed very frequently due to the increase in repetitive injuries.
Most frequently, numbness will affect one extremity and is most often diagnosed as a peripheral neuropathy. A very common form of nerve damage (peripheral neuropathy) is to the nerves that make up the brachial plexus as they exit the spinal column through the foramina. Neck pain or stiffness may be one of the first signs of brachial plexus damage. In some people the pain may radiate to the shoulder and down to the arm, wrist, hand or finger. Sometimes symptoms appear only in the extremity but not in the neck. Very frequently, nerve entrapment occurs in the neck and involvement in the hands and arms come from the neck (cervical spine). The canal space becomes blocked because of additional bone growth around the canal. The nerve as it passes through becomes compressed (pinched). What causes the nerves to become compressed? Examples are long standing spinal stress, old injuries such as falls off the bike, falling out of a tree, an old sports injuries, or even car accidents (whiplash).
Depending on which nerves are damaged, symptoms may appear in different areas of the extremity. Initial symptoms of a peripheral entrapment syndrome (pinched nerve) come primarily from the involved muscle. An adequate nerve supply must be present for all muscles to work efficiently. Therefore, when a nerve traveling to supply a muscle becomes pinched, the muscle will become weak, and then begin to fasciculate (twitch). Deinnervation (limited nerve supply) of the muscle causes muscle wasting supplied by that particular nerve. A peripheral neuropathy will always follow a specific pattern of distribution.
Symptoms vary and need to be carefully described as to their exact nature. Therefore, a careful evaluation of the patient’s complaint is necessary for accurate assessment of the patient’s condition.
In reality, numbness or tingling in one or more extremity, does not always indicate a pathological condition is present. Different tissues may be involved with the same type of symptoms. Mode of injury must always be carefully considered. For example, trauma to an area may result in vascular, or neurological compromise. Other considerations for diagnosis must include a metabolic disorder, overuse syndrome, Intervertebral disc syndrome, fracture, vascular compromise leading to ischemia, tumor, canal stenosis (nerve root lesion), peripheral entrapment neuropathy, or suprasegmental involvement of central structures (brain, brainstem, cerebellum and spinal cord).