brain, spinal cord, and nerve disorders
Numbness
Evaluation of Numbness
Because so many disorders can cause numbness, doctors ask questions systematically, focusing on more likely causes. In people with numbness, the following symptoms are cause for concern: Numbness that begins suddenly (within minutes or hours) Weakness that accompanies the numbness and that begins suddenly or rapidly (within hours or days) Numbness or weakness that rapidly spreads up or down the body, involving more and more parts of the body Difficulty breathing Numbness in the thighs, buttocks, genitals, and the area between them (saddle area) and loss of bladder and bowel control (incontinence) Numbness on both sides below a specific level of the body (such as below the midchest) Numbness of an entire leg or arm Loss of sensation in the face and torso People who have warning signs should go to a hospital immediately. People without warning signs should call their doctor. The doctor can decide how rapidly they need to be seen based on their symptoms. Doctors begin by asking which body parts are affected. The pattern of body parts affected by numbness often indicates which part of the nerve pathway is malfunctioning: Part of a limb: Peripheral nerve or sometimes spinal nerve root malfunction Arm and leg on the same side of the body: Brain malfunction Both sides of the body below a specific level of the body: Spinal cord malfunction, as occurs in Acute Transverse Myelitis (which causes inflammation across the entire width of the spinal cord) Both sides, mainly in the hands and feet: Simultaneous malfunction of many peripheral nerves throughout the body (a Polyneuropathy ) Then doctors ask about the person's other symptoms and Medical History in Neurologic Disorders . Doctors also do a physical examination. What they find during the history and physical examination often suggests a cause and the tests that may need to be done (see table Doctors ask the person to describe the numbness. Then doctors may ask specific questions: When numbness began How quickly it began Whether the person also has other symptoms such as abnormal sensations, weakness or paralysis, loss of bowel or bladder control, retention of urine, vision problems, difficulty swallowing, or deterioration of mental function Whether any event, such as pressure on a limb, an injury, sleeping in an awkward position, or an infection, triggered the symptoms Knowing how quickly numbness and other symptoms began helps doctors determine the type of disorder. The person is asked about symptoms that may suggest a cause. For example, back and/or neck pain suggests osteoarthritis, a ruptured disk, or another disorder that puts pressure on the spinal cord. Doctors also ask whether the person has had a disorder that can cause numbness, particularly diabetes, chronic kidney disease, infections (such as HIV infection or Lyme disease), a stroke, or arthritis. Doctors may ask whether any family members have had similar symptoms or have a hereditary disorder that affects the nervous system. They ask the person about use of medications and substances (including illicit drugs), and about possible exposure to toxins. The physical examination includes a complete evaluation of the nervous system ( Neurologic Examination ), focusing on testing sensation (whether the person can feel stimuli, such as touch and temperature, normally), as well as reflexes and muscle function. Testing is not needed if the diagnosis is obvious and treatment involves only general measures (such as rest or a splint)—for example, in some cases of carpal tunnel syndrome. In other cases, tests are done based on where doctors think the problem is: For sensory nerves, plexuses, or spinal nerve roots: Nerve conduction studies and electromyography For plexuses: Nerve conduction studies and electromyography and sometimes magnetic resonance imaging (MRI) after a contrast agent is injected into a vein For the brain or spinal cord: MRI or, if MRI is not readily available, computed tomography (CT) Electromyography and Nerve Conduction Studies are often done at the same time. Nerve conduction studies use electrodes or small needles to stimulate a nerve. Then doctors measure how fast the nerve transmits signals. For electromyography, a small needle is inserted into a muscle to record its electrical activity when the muscle is at rest and when it is contracting. Other tests are then done to identify the specific disorder. For example, if results suggest a polyneuropathy, doctors do blood tests to check for its various causes (such as diabetes, kidney disorders, or vitamin deficiencies). 