CIDP causes muscle weakness and numbness, among other symptoms. Diagnosing CIDP involves peripheral nervous system testing, cerebrospinal fluid analysis, and imaging.
CIDP is an immune-mediated condition affecting your peripheral nerves. It occurs when immune cells attack the protective covering around nerves known as the myelin sheath. It can also occur when dysfunction in the immune system causes inflammation that leads to myelin sheath breakdown.
CIDP affects peripheral nerves and those outside the central nervous system (CNS), the brain, and the spinal cord. Symptoms of progressive muscle weakness, numbness, and decreasing reflexes are often noticed in areas of the body, like the arms and legs.
When doing a CIDP evaluation, your doctor will often consider your symptom history first. However, as part of the diagnosis, they’ll also likely run several tests to rule out other possible causes and verify nerve involvement.
CIDP can be challenging to diagnose. Its presenting symptoms may be similar to other conditions affecting the nervous system, which include motor neuron disease, diabetic polyneuropathy, and Guillain-Barre syndrome (GBS).
Generally, CIDP symptoms emerge slowly over at least 2 months and feature weakness developing symmetrically on both sides of the body. Lack of deep reflexes and a pattern of weakness in both shoulders, hands, and feet, along with
To determine whether CIDP is the cause of your symptoms, your doctor will run various tests. The goal is to rule out other causes, determine the involvement of the peripheral nervous system, confirm myelin sheath damage, and verify the presence of immune-mediated inflammation.
The journey to a CIDP diagnosis can take time. Parts of the diagnostic process can be quick, but it may take longer to schedule certain procedures. Depending on the test, you may also have to wait longer for results.
Neurological exam
Testing for CIDP starts with a basic neurological exam. When you visit your doctor with initial symptoms, a neurological exam can provide insight into basic functions related to mental state, coordination, reflexes, sensory input, and movement control.
Your doctor scores your neurological responses through tests like watching your gait, assessing your eye movement, testing your strength and reflexes, and checking how you respond to various touch pressures. During this early assessment, a doctor can often note loss of nerve function from CIDP.
Nerve conduction studies
Doctors place electrodes on your skin over the nerve under assessment. A mild electrical pulse then travels down the nerve, and the electrodes measure how quickly (and at what strength) it takes for the signal to get between electrodes.
You might experience a mild tingling sensation during the test. The length of time that the test will run varies. Depending on the number of nerves tested, NCSs can last anywhere from 15 minutes to over an hour.
Electromyography
Like NCSs, EMG uses electrodes. The procedure involves inserting needle electrodes into the muscle or placing surface electrodes on top of the muscles. These measure electrical activity when your muscle is at rest and when it is in use, recording the frequency, duration, and strength of the signals.
EMG tests typically take between 30 to 60 minutes. Tingling sensations are possible, and if your doctor uses needle electrodes, you may experience mild discomfort when the needle enters the muscle. Soreness or bruising at the needle sites may develop.
Cerebrospinal fluid analysis
A cerebrospinal fluid (CSF) analysis assesses the fluid surrounding your brain and spinal cord. It’s performed through a lumbar puncture, also known as a spinal tap. In CIDP, your doctor checks CSF for elevated protein levels creating a condition called albuminocytologic dissociation.
CSF collection takes place in a hospital or clinical setting with sterilized equipment and local anesthesia. You’ll sit or lie on your side while your doctor inserts a small needle between two vertebrae and into the subarachnoid space to collect the CSF fluid.
Even though CSF sampling is relatively quick, the procedure may take over an hour due to the sterile preparation of the site and recovery afterward. Pain or tenderness at the needle insertion site is possible after the anesthetic wears off, and some people may experience a headache.
Nerve biopsy
A nerve biopsy isn’t considered standard practice for diagnosing CIDP. However, according to a 2022 research review, it may be useful when diagnosing CIDP variants or forms of CIDP that don’t follow the classic presentation.
To perform a nerve biopsy, your doctor takes a small tissue sample from your nerve for evaluation by a pathologist at a laboratory. The pathologist examines the tissue for signs of inflammation, myelin sheath breakdown, and other irregularities.
Like CSF analysis, a nerve biopsy requires sterile procedures and local anesthesia in a clinical setting. Your doctor makes a small incision to remove the nerve sample and then closes the opening with stitches or surgical strips.
The time it takes to perform a nerve biopsy varies significantly. It’s typically an outpatient procedure, and you should be able to return home the same day.
MRI
MRI is a diagnostic imaging process that helps your doctor visualize patterns of nerve root enlargement and inflammation specific to CIDP. However, MRIs are usually reserved for atypical cases and are not necessary to make a diagnosis. Doctors can use it as an additional test if other core tests are inconclusive.
MRI uses a magnetic field and radio waves to create images of the nerves inside your body. To evaluate CIDP, your doctor may inject a contrast agent into your vein during the MRI to help highlight areas of nerve damage and inflammation.
MRIs take an average of 20 to 60 minutes. Without a contrast agent, the procedure is noninvasive and involves lying very still inside a tube-like machine. Some people report a twitching sensation during MRIs, and ear protection may be advisable to mute the sounds of the machine.
Preliminary results of your CIDP diagnostic tests may be available same-day, but you’ll likely have to wait several days or weeks for your final report.
Laboratory samples take time to send out and evaluate. A neurologist or another specialist will review in-clinical test results to create an official report.
While you wait for a definitive CIDP diagnosis, your doctor will create a management plan for your current symptoms. This plan may involve pain relief, physical therapy, lifestyle changes, and psychological support.
CIDP is a condition affecting your peripheral nervous system. While your doctor may consider CIDP to be the cause of any muscle weakness and reflex loss based on an initial neurological exam, an official diagnosis requires diagnostic testing.
NCSs, EMGs, and CFS analysis are core components for determining a CIDP diagnosis. When the presentation is unusual, your doctor may consider additional tests, like a nerve biopsy. Other scans, bloodwork, and laboratory tests may be necessary to rule out other neurological conditions.