How to Diagnose Peripheral Neuropathy

Peripheral neuropathy is a general term used for a series of disorders caused by damage to the body’s peripheral nervous system. It is not a single disease.

The nervous system is made up of the Central Nervous System (CNS) which includes the spinal cord and brain, and the peripheral nervous system (PNS) which connects the nerves running from the spinal cord and brain to the rest of the body organs like hands and arms, internal organs, legs and feet, joint, and the eyes, mouth, nose, ears, and skin.

When the nerves are destroyed or damaged and can’t send signals to the skin, muscles, and other body parts from the brain and spinal cord, peripheral neuropathy occurs. Peripheral nerves go from the brain and the spinal cord to the hands, arms, feet, and legs. When there is damage, pain, and numbness in these areas could also occur.

Peripheral neuropathy can affect only one nerve group or nerve at a time, commonly referred to as mononeuropathy; it can also affect multiple nerves, known as polyneuropathy.

Mononeuropathy is caused by damage to a single nerve group or nerve by injury, trauma, prolonged pressure, local compression, or inflammation. For example, Bell’s palsy, a facial nerve disorder, and Carpal tunnel syndrome, a painful hand and wrist disorder associated with repetitive tasks like typing. 

How Peripheral Neuropathy is Diagnosed

Many things can cause peripheral neuropathy. Hence, besides a physical exam that could include blood tests, a diagnosis could require more.

Before a proper diagnosis, the doctor will want to know and review your medical history. A full medical history will include your symptoms, exposure to toxins, your lifestyle, family history of neurological diseases, as well as drinking habits.

The doctor may also ask for a neurological examination to check your tendon reflexes, muscle tone and strength, your posture and coordination, and your ability to feel certain sensations. The doctor may also order tests like blood tests to try and detect diabetes, vitamin deficiencies, abnormal immune functions, and indications of other conditions that could cause peripheral neuropathy.

The doctor may also ask for imaging tests like MRI, or CT scans to look for tumors, herniated disks, or other abnormalities. Nerve function tests like EMG (Electromyography) can also help record electrical activity in the muscles to detect any nerve damage. 

With EMG, a thin needle is inserted into the muscle to help measure electrical activity as the patient contracts the muscle. The EMG technician or doctor will typically perform a nerve conduction study by placing flat electrodes on the skin to let a low electric current stimulate the nerves. The nerves’ responses to the electric current are then recorded.

Your doctor could also need other nerve function tests that could include an autonomic reflex screen that records how your autonomic nerve fibers work. They could also want sensory tests to record how you feel touch, heat, cooling, and vibration, as well as a sweat test to measure your body’s ability to sweat.

A nerve biopsy could also help look for abnormalities by removing a small portion of a sensory nerve. A skin biopsy, where the doctor removes a small skin portion, will help look for a reduction in nerve endings if any. With results from either of these tests, the doctor can diagnose you with peripheral neuropathy if he sees evidence of it.