Cause | Common Features* | Diagnostic Approach† |
---|---|---|
Numbness in both limbs (arm and leg) on one side of the body | ||
Disorders that affect the outer layer of the cerebrum (the largest area of the brain), such as
| Loss of sensation on the opposite side of the face and body from the side of the brain that is affected by the disorder and loss of the ability to recognize items by touch Usually weakness, loss of coordination, and other symptoms indicating malfunction of the nervous system | MRI or CT of the brain |
Disorders that affect the upper part of the brain stem, such as | Loss of sensation on the opposite side of the face and body from the side that is affected by the disorder Often double vision | MRI or CT of the brain |
Disorders that affect the lower part of the brain stem, such as
| Loss of sensation on same side of the face and on the opposite side of the body from the side that is affected by the disorder Often vision problems and difficulty chewing, swallowing, and speaking | MRI of the brain |
Numbness in the limbs or torso on both sides | ||
Disorders that affect the width of the spinal cord, such as
| Loss of sensation and usually weakness below a certain level of the body No loss of sensation in the face Usually retention of urine, loss of bowel and bladder control (incontinence), and/or reduced sexual response, including erectile dysfunction in men | MRI of the spinal cord |
Cauda equina syndrome Cauda Equina Syndrome Cauda equina syndrome occurs when the bundle of nerves that extends from the bottom of the spinal cord is compressed or damaged. The most common cause of cauda equina syndrome is a herniated... read more , caused by pressure, as may result from
| Numbness mainly in the thighs, buttocks, bladder, and genitals, and—the area that would touch a saddle (saddle area) Usually pain in the lower back Often retention of urine, loss of bowel and bladder control, and/or reduced sexual response, including erectile dysfunction in men | MRI of the spinal cord |
Central cord syndrome (which may result from injury, a tumor, or syrinx Syrinx of the Spinal Cord or Brain Stem A syrinx is a fluid-filled cavity that develops in the spinal cord (called syringomyelia), in the brain stem (called syringobulbia), or in both. Syrinxes may be present at birth or develop later... read more ) | Numbness and weakness that affects mostly the shoulders and arms | MRI |
Polyneuropathies Polyneuropathy Polyneuropathy is the simultaneous malfunction of many peripheral nerves throughout the body. Infections, toxins, medications, cancers, nutritional deficiencies, diabetes, autoimmune disorders... read more (simultaneous malfunction of many peripheral nerves throughout the body), as may result from
| Numbness and abnormal sensations in about the same areas on both sides of the body, mainly in the feet and hands Sometimes weakness and loss of reflexes | Nerve conduction studies Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more (measuring how fast nerves transmit signals) and electromyography Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more (stimulating muscles and recording their electrical activity) Other tests depending on the disorder suspected |
Demyelinating disorders Overview of Demyelinating Disorders Most nerve fibers inside and outside the brain are wrapped with many layers of tissue composed of a fat (lipoprotein) called myelin. These layers form the myelin sheath. Much like the insulation... read more (disorders that cause nerves to become inflamed and lose their outer layer, called the myelin sheath), such as
| Often weakness or clumsiness and abnormal sensations (such as tingling or numbness) Sometimes changes in vision or speech | MRI of the brain and spinal cord Spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more (lumbar puncture) to examine a sample of cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) |
Numbness in part of one limb | ||
Disorders that affect a spinal nerve root such as
| Pain that
Often weakness and/or reduced or absent reflexes in the area supplied by the nerve root | MRI or CT of the spinal cord Sometimes nerve conduction studies and electromyography |
Disorders that affect a plexus Plexus Disorders Plexuses (networks of interwoven nerve fibers from different spinal nerves) may be damaged by injury, tumors, pockets of blood (hematomas), or autoimmune reactions. Pain, weakness, and loss... read more (a network of nerve fibers), such as
| Numbness, pain, and/or weakness in a relatively large area of a limb | Nerve conduction studies and electromyography MRI |
Mononeuropathy Mononeuropathy Mononeuropathy is damage to a single peripheral nerve. Pressure on a nerve for a long time is the most common cause of mononeuropathy. The affected area may tingle, feel prickly, or be numb... read more (malfunction of one peripheral nerve), as occurs in | Numbness with or without pain Often weakness and reduced or absent reflexes in an area supplied by one nerve | Sometimes a doctor's examination alone Sometimes nerve conduction studies and electromyography |
* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present. | ||
† Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made by the doctor's examination alone, without any testing. | ||
CT = computed tomography; MRI = magnetic resonance imaging. |