Peripheral neuropathy describes damage to the nerves located outside of the brain and spinal cord, which make up the peripheral nervous system. These nerves transmit signals between the central nervous system and the rest of the body, affecting movement, sensation, and automatic functions. Chronic Inflammatory Demyelinating Polyneuropathy, or CIDP, represents a rare, serious form of acquired neuropathy that can be progressive or relapsing. This condition causes long-term symptoms that worsen over at least eight weeks, distinguishing it from acute forms of inflammatory neuropathy.
The Autoimmune Mechanism of CIDP
CIDP is classified as an autoimmune disorder, meaning the body’s immune system mistakenly attacks its own healthy tissues. In this condition, the target of the immune attack is the myelin sheath, the protective layer of fatty tissue that insulates the peripheral nerves. This myelin covering is analogous to the insulation around an electrical wire, allowing electrical impulses to travel quickly and efficiently along the nerve axon.
The immune system’s inflammatory response results in the breakdown of this myelin sheath, a process known as demyelination. When myelin is damaged, the nerve signals slow down, weaken, or may fail to reach their destination entirely. This loss of insulation and subsequent interruption of electrical communication is what causes the neurological symptoms experienced by patients.
Identifying Common Symptoms
The clinical presentation of CIDP typically involves both motor and sensory impairments that often affect both sides of the body symmetrically. Motor symptoms commonly include progressive muscle weakness, making simple tasks like walking, climbing stairs, or getting out of a chair difficult. Weakness often begins in the legs but can also involve the upper arms and hands, sometimes leading to a loss of muscle mass over time.
Sensory symptoms frequently manifest as abnormal sensations, such as tingling, prickliness, or numbness, particularly in the fingers and toes. Neuropathic pain, which can range from mild discomfort to intense burning or sharp sensations, is also common. The combination of muscle weakness and sensory loss often results in difficulties with balance, coordination, and a loss or weakening of deep tendon reflexes. The condition’s course is often characterized as either gradually progressive, worsening over months or years, or relapsing-remitting, where symptoms stabilize or improve before coming back.
Confirming a CIDP Diagnosis
Diagnosing CIDP requires a physician to combine clinical assessment with specific laboratory and electrodiagnostic tests to confirm the presence of demyelination and exclude other causes of neuropathy. A cornerstone of the diagnostic process is electrodiagnostic testing, which includes Nerve Conduction Velocity (NCV) studies and Electromyography (EMG). NCV studies measure the speed and strength of electrical signals in the nerves, typically revealing slowed conduction velocity or conduction block due to myelin damage.
Another important procedure is a lumbar puncture, which involves collecting a sample of cerebrospinal fluid (CSF) from the lower back. In approximately 85% to 90% of CIDP cases, analysis of the CSF shows a characteristic finding known as albuminocytologic dissociation. This means there is an elevated protein level, specifically albumin, in the fluid without an accompanying increase in white blood cells. This high protein level suggests that damaged peripheral nerves and nerve roots are leaking protein into the CSF space.
Primary Medical Treatments
First-line therapies focus on immunomodulation, with three main options supported by clinical evidence.
Intravenous Immunoglobulin (IVIg)
Intravenous Immunoglobulin (IVIg) therapy involves infusing a concentrated solution of antibodies collected from healthy donors into a vein. IVIg is thought to block the autoantibodies responsible for the nerve damage and regulate the inflammatory process.
Corticosteroids
Corticosteroids are also a standard treatment option, working to broadly suppress the immune system and reduce inflammation. These drugs mimic the body’s natural hormones that help regulate immune activity, though long-term use is often limited by potential side effects.
Plasma Exchange (PLEX)
Plasma Exchange (PLEX), or plasmapheresis, is a procedure that physically removes a patient’s blood plasma, filters out harmful antibodies and inflammatory proteins, and returns the blood cells suspended in a replacement fluid. PLEX is typically used when patients have an urgent need for improvement or do not respond adequately to IVIg or corticosteroids.