A neuropathy is any disease of neurons. Neuropathies outside of the brain and spinal cord are referred to collectively as peripheral neuropathies. The term "sensorimotor neuropathy" refers to a peripheral neuropathy that damages the motor nerves, which control muscles, and the sensory nerves, which carry touch, temperature, pain and pressure information from the body to the brain. Sensorimotor neuropathy can be caused by infection with inflammation, metabolic disorders and inherited conditions, but it is most commonly a complication of diabetes.
Diagnosis of sensorimotor neuropathy begins with a neurological exam and usually includes an electromyogram and a nerve conduction velocity test to measure the speed with which nerves are carrying electrical current. Blood tests are essential to determine whether a metabolic disorder is present and to check blood sugar if the patient is not a known diabetic. Treatments usually focus on the underlying condition, though pain medication and anti-inflammatory agents might also be given. Treatment success varies with the cause — neuropathies because of metabolic problems or inflammation are much more manageable than genetically inherited ones.
Diabetic sensorimotor neuropathy is a common side effect of diabetes and can cause loss of sensation, lack of muscle control, muscular weakness and muscular atrophy as well as frequent injury because patients cannot feel one of their limbs. Diabetics who have high blood sugar might have excessive intracellular glucose inside their peripheral neurons, and it gets converted into other sugars that impair the structure and function of the nerve. Intracellular glucose can also bind to proteins in the cell and prevent them from carrying out their normal functions, and destruction of the blood vessels that supply the peripheral nerves deprives neurons of oxygen, leading to cell death. Treatment requires managing blood sugar levels better, but the damage often is irreversible, and foot amputations frequently result.
Sensorimotor polyneuropathy involves systematic loss of feeling and muscle control in the entire body. Those who are affected with this form of nerve damage are especially at risk of injuring nerves in their knees, elbows and other joints by prolonged pressure, and they must change their position frequently to prevent injury. Polyneuropathies sometimes cause not only sensorimotor neuropathy but autonomic nervous system damage as well. Autonomic involvement threatens basic functions such as breathing, bladder control and digestion.
Metabolic disturbances from toxins, diabetes, advanced alcoholism or severe B-vitamin deficiency are common causes of polyneuropathy and can be identified quickly with the right tests. Some sensorimotor neuropathies result, instead, from inflammation that strips away the nerve cell's myelin, the neuron's protective sheath that enables rapid electrical conduction from cell to cell. This is the case with Guillain-Barre syndrome, a serious and rare polyneuropathy leading to paralysis. Although it requires hospitalization with respiratory support and filtration of antibodies in the bloodstream to reduce the inflammation, many patients recover completely. The rate of permanent sensorimotor damage is less than 10 percent.