Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Introduction:

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a progressive autoimmune disease that destroys the myelin sheaths of peripheral nerves (latov; Janssen et al). Individuals with this nervous system disorder tend to present physically with symmetrical weakness, balance problems, impaired sensation and diminished reflexes in addition to problems at a neurological level (latov, Janssen et al., 2018). The long term nature of this condition leads to abnormalities in gait and impairments in both psychological and social functioning (Janssen et al., 2018).

Clinically Relevant Anatomy:

The human nervous system can be divided into 2 parts. The central nervous system, which includes the brain and spinal cord, and the peripheral nervous system, which contains all nerves that supply the rest of the body. Surrounding the peripheral nerves is a white, fatty layer of myelin that is made up of glial cells, termed Scwhann cells. The myelin coating generated by the Schwann cells assists the axons in transmitting faster neural impulses to receptor sites, such as organs and muscles. In CIDP this myelin is destroyed resulting in nerve conduction changes and impairments, such as limb weakness and sensory loss. (textbook-)

Pathophysiology:

CIDP can be distinguished into two categories; typical and atypical cases. Symmetric motor/sensory impairments with proximal and distal weakness and areflexia, slowed conduction rate, temporal dispersion, and/or a conduction block occurs in typical cases of CIDP. Atypical cases can present in a number of different ways. Most commonly atypical cases are purely sensory or predominantly sensory, multifocal with persistent conduction block, and cases that present with similar and bilateral distal symptoms. (LEWIS)  Pathological changes have been seen to be more pronounced in the spinal nerve roots, major plexuses, and proximal nerve trunks. Magnetic resonance imaging (MRI) studies following patients for an extended period of time have concluded that nerve hypertrophy and/or gadolinium enhancement are more prominent in these areas.  (Mathey, Pollard)

Gadolinium- define!

Immunopathology:

When looking at the immunopathology of CIDP the two important cells to analyze are T and B lymphocytes. They both play a primary role along with macrophage cells in myelin phagocytosis as seen within nerve lesions of CIDP. Additionally, T cells play an important role in the increased permeability of the blood nerve barrier as seen on MRI studies of inflammatory neuropathies. A high percentage of patients with CIDP have been shown to have positive outcomes to plasma exchange therapy. This suggest that the antibody or other soluble factors are pathogenic in this disease. (Mathey and Pollard).

Epidemiology (edited by M)

Incidence: CIDP is suspected to be vastly underestimated, in part due to underreporting, uncertainty in making the diagnosis and diagnostic criteria inconsistencies (latov). Many research studies report different distributions of cases with diagnostic numbers as low as 0.5 per 100,000 children and 1 to 2 per 100,000 adults (koller) to as high as 8 per 100,000 (foundation guidelines)

Gender: Although research is limited, there is a slight predilection for men (gorson, lewis)

Age: Individuals diagnosed with CIDP are generally aged 40-60, although children and elderly people may be affected (Gorson)

Clinical Presentation - C reviewed over

Individuals often report difficulty with walking, climbing stairs, balance and manual dexterity, which is attributed to the progressive, symmetric limb weakness and sensory loss. It is commonly seen to affect proximal muscles in the early stages and then progressively move to the distal limbs. Numbing, buzzing and tingling may be characteristic of sensory loss reported by patients and neuropathic pain is less often reported. (Garson)

On the contrary, some individuals may not present with these symptoms, which makes diagnosis much more difficult and can take many years, leaving patients with no answers and increased frustration. (Wolfe and Greer, 2015).

After complete subjective and objective history in addition to further medical investigations, which may take multiple months after symptom onset, the following aspects have been recognized as major cardinal features of CIDP (lewis):

1. Progression over at least 2 months

2. Predominant motor symptoms

3. Symmetric involvement of arms and legs

4. Proximal muscles involved along with distal muscles

5. Deep tendon reflexes reduction or absence

6. Cerebrospinal fluid (CSF) protein elevation without pleocytosis

7. Nerve conduction evidence of a primary demyelinating neuropathy

Differential Diagnosis- edited by M

• Multifocal motor neuropathy
• Diabetic polyneuropathy
• Fibromyalgia
• Multiple sclerosis
• Amyotrophic lateral sclerosis (ALS)
• Guillain-Barre syndrome (GBS)
• Neuropathy associated with: nutritional deficiencies, critical illness, toxins, systemic inflammatory diseases

Lewis, koller^^^

Global muscle weakness of the upper and lower extremities, the reduction of deep tendon reflexes and aggressive course of the disease are distinguishing factors between CIDP and chronic length-dependent peripheral neuropathies (Lewis, 2007).

The demyelinating form of Guillain-Barre syndrome (GBS), which is a form of acute inflammatory demyelinating polyneuropathy (AIDP), and CIDP are quite similar in nature and are differentiated by their time of progression (Lewis, 2007). GBS often occurs after an identifiable infectious illness, vaccination or surgery, 3-4 weeks prior to the onset of symptoms.  In comparison, CIDP often does not have an easily identifiable antecedent event and progresses for 8 weeks or more. (lewis, Garson).

As stated previously, CIDP is suspected to be vastly underestimated (latov). On the contrary, there is research suggesting that a misdiagnosis of CIDP commonly occurs in other neurologic conditions (allen/lewis). This misdiagnosis is attributed to the lack of implementation of specific clinically relevant criteria and electrodiagnostic criteria. One study even determined that a whopping, “Forty-seven percent of patients referred with a diagnosis of CIDP failed to meet minimal CIDP diagnostic requirements,” (allen & lewis). The amount of underreporting and misdiagnoses demonstrates the importance of implementing the most current and valid diagnostic criteria.