Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Authors:

Bao Quoc Nguyen MD,

Junaid Kalia MD

Welcome video from the author

Introduction

• Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare immune-mediated disorder affecting the peripheral nervous system

• Typical manifestations include proximal and distal sensory and motor impairment in four limbs, developing over more than 08 weeks

• Treatment consists of three therapies: glucocorticoids, intravenous immune globulin (IVIG), and plasma exchange

• Approximately 30% of patients with CIDP will achieve cure or remission

Epidemiology

• Prevalence: 0.7 to 10.3 cases per 100,000 people [6]

• Incidence: [2035]
• ↑ with advancing age
• Peaks at 40-60 years of age
• Male-to-female ratio: 2:1

Etiology

• The causes of CIDP and its variants remain unknown

• Unlike acute inflammatory demyelinating polyneuropathy (AIDP), there is no specific predisposing risk factors for CIDP have been evidently recognized [7]

Pathophysiology

• CIDP is immune-mediated involving in both the cellular and humoral immunity system
• Cellular immunity: evidence of T cell activation, expression of cytokines, tumor necrosis factor, interferons, and interleukins [827,32]
• Humoral immunity: immunoglobulin (Ig) and complement deposition was found on myelinated nerve fibers. In an experiment on rats, injecting purified IgG from CIDP patients induced conduction block and demyelination [42]

• The specific immunologic triggers of CIDP in the majority of patients remain unclear

Clinical features

Typical CIDP

• The most common subtype, accounting for ~50 to 60 percent of all cases [710]

• SYMMETRIC nerve damage pattern

• Motor involvement > sensory involvement

• Motor symptoms:
• A similar degree of weakness in both proximal and distal muscles (non-length-dependent pattern)
• Proximal muscle weakness:
• Difficulty walking, climbing or descending stairs, rising from a seated position, and lifting objects overhead
• Distal muscle weakness:
• Tripping over the feet due to "foot drop," difficulty with fine motor tasks (e.g., buttoning, tying shoelaces), and difficulty opening doors or jars
• Cranial nerve and bulbar involvement was reported in 10 to 20 percent of patients

• Sensory symptoms:
• Global diminished or absent reflexes
• CIDP attacks nerves’ myelin → nerve fibers with the most myelin (motor and proprioceptive fibers) are MORE vulnerable than those with little or no myelin (autonomic and pain fibers)
• Proprioception impairment → gait ataxia
• Worse distally, starting with fingers and toes

• Autonomic involvement is uncommon [14]

• Typical CIDP could present in an acute fashion (acute-onset CIDP [A-CIDP]) in up to 13% of patients who may initially be misdiagnosed with Guillain-Barré syndrome (GBS) [29,30]
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There are NO specific clinical signs or laboratory tests that can differentiate between GBS and A-CIDP

CIPD variants

• Typical CIDP and CIDP variants are distinguished by their clinical presentation and/or pathogenic mechanism, but are not always clearly defined [10]

Distal CIDP

• Also known as Distal Acquired Demyelinating Symmetric neuropathy (DADS) [19]

• Symmetric sensory or sensorimotor defected in the lower extremities except for proximal limbs, trunk, and face [10]. Upper extremities involvement may present in the later stage

• Patients with signs and symptoms of DADS are likely to have a monoclonal gammopathy. Further hematologic workup may reveal either monoclonal gammopathy of clinical significance (MGCS) or Waldenström macroglobulinemia [13]

Multifocal CIDP

• Also known as Lewis-Sumner syndrome, or Multifocal Acquired Demyelinating Sensory and Motor Neuropathy (MADSAM)

• Remarkable asymmetric and multifocal neurological defects; maybe indistinct to mononeuropathy multiplex [21,28]

• Autonomic symptoms, neuropathic pain, and cranial nerve involvement have been previously reported [10]

Motor CIDP

• Rare variant [931]

• Symmetric proximal and distal weakness with normal sensation on both clinical and electrodiagnostic evaluation; may involve motor cranial nerves [10]

• Difficult to be distinguished between lower motor neuron-predominant amyotrophic lateral sclerosis and multifocal motor neuropathy

Focal CIDP

• Rare variant

• May affect the brachial or lumbosacral plexus or individual peripheral nerves [3438]

Sensory CIDP

• Characterized by large-fiber sensory dysfunction, including gait ataxia, vibration and position sense impairment, and dysesthesias

• If combined with slow motor nerve conduction or motor conduction blocks → sensory-predominant CIDP

• ~70% of patients showed weakness in the later clinical stage [10]

Diagnostic Evaluation

Electrodiagnostic testing

• Should be conducted in ALL patients with suspected CIDP

• Extensive electrodiagnostic studies of the upper extremities or all four extremities are recommended

• A critical component in the EFNS/PNS diagnostic criteria (discussed below)

Laboratory studies

• There are NO specific laboratory findings pointing to CIDP

• The goal is to search for conditions either associated with or imitate CIDP, including diabetes mellitus, IgG or IgA monoclonal gammopathy of undetermined significance (MGUS), IgM monoclonal gammopathy without antibodies to MAG (anti-myelin-associated glycoprotein), HIV infection, or malignancies [37]

• The common work-up panel is as followed:
• Complete blood count (CBC)
• Fasting serum glucose
• Glycated hemoglobin (HbA1C)
• Liver function
• Renal function
• Serum protein electrophoresis (SPEP) and immunofixation
• Serum free light chain (FLC) assay, or 24-hour urine protein electrophoresis (UPEP) and immunofixation

• In particular scenarios or in patients with atypical presentations, additional tests should be considered to rule inflammatory or infective causes as comported to autoimmune:
• Borrelia burgdorferi serology
• C-reactive protein
• Antinuclear antibodies (ANAs)
• Angiotensin-converting enzyme
• Hepatitis panel (for types B and C)
• HIV antibody
• Chest radiograph
• Nodal-paranodal protein antibodies
• Skeletal survey
• Genetic screening for Charcot-Marie-Tooth (CMT) disease or transthyretin (TTR) familial amyloid polyneuropathy (FAP)

Lumbar puncture

• Not indicated if the diagnosis of CIDP is clear

• To exclude other causes or serve as supportive criteria in the EFNS/PNS diagnostic criteria

• ~80% of patients with CIDP showed elevated protein (>45 mg/dL) and normal white cell count in cerebrospinal fluid (CSF) [2,1617] An elevated CSF white cell count of >10 cells/mm3 suggests a different diagnosis (infection, inflammation, or malignancies)

Neuroimaging

• Magnetic resonance imaging (MRI) with gadolinium of the spine (including spinal roots, cauda equina), brachial plexus, lumbosacral plexus, and other nerve regions can reveal enlarged or abnormal nerves

• Indicated in patients with an unusual presentation, especially when clinical and electrophysiologic findings are focal, and to rule out other neuropathy and infiltrative pathology [11] (e.g., chronic immune sensory polyradiculopathy [CISP], chronic immune sensorimotor polyradiculopathy [CISMP])

• MRI abnormalities are one of the supportive criteria for CIDP in the EFNS/PNS diagnostic criteria

Nerve ultrasound

• May indicate when experts are available

• Can detect nerve hypertrophy; although the findings are not specific to CIDP, it may narrow down the lesion location

• Served as supportive criteria for CIDP in the EFNS/PNS diagnostic criteria

Nerve biopsy

• The utility is controversial [436]

• Consider indicating when:
• Other studies fail to establish the diagnosis of CIDP
• There is a high suspicion of an infiltrative or systemic process that may mimic CIDP (e.g., amyloidosis [23], sarcoidosis, and vasculitis [3])

• CIDP is multifocal in nature, plus motor fibers tend to be more affected than sensory nerves (the usual target of biopsy procedure) → difficult to catch demyelination evidence on the biopsy specimens

• Characteristics supporting the diagnosis of CIDP on nerve biopsy include
• Thinly myelinated axons and small onion bulbs [15]
• Thinly myelinated or demyelinated internodes in teased fibers [41]
• Perivascular macrophage clusters [33]
• Signs of demyelination on electron microscopy [36]

Diagnosis

• There is NO gold standard to diagnose CIDP

• We recommend using the EFNS/PNS diagnostic criteria due to their superior accuracy compared to other criteria [518]

• To serve our scope for this chapter, we mainly focus on typical CIDP, which occupies the majority of CIDP cases

Diagnostic Approach according to the EFNS/PNS

Step 1: Clinical Determination of CIDP

Step 2: Electrodiagnostic assessment

Step 3: Differentiate between typical and atypical CIDP

• Typical CIDP:
• Abnormal motor conduction in 2 nerves
• Abnormal sensory conduction in at least 2 nerves

• Possible CIDP: two circumstances
1. Abnormal motor conduction in 1 nerve AND 02 supportive criteria (mentioned below)
2. No abnormal motor conduction AND objective treatment* improvement AND 01 supportive criteria
*including IVIG, glucocorticoids, or plasma exchange

Supportive criteria

• Elevated CSF protein with leukocyte count <10/mm3

• MRI with gadolinium shows an enhancement and/or hypertrophy of the cauda equina, lumbosacral or cervical nerve roots, or the brachial or lumbosacral plexuses

• Response to standard treatment

• Nerve biopsy showing evidence of demyelination and/or remyelination by electron microscopy or teased fiber analysis

Differential diagnosis

• Typical CIDP
• AL amyloidosis, ATTRv polyneuropathy
• Chronic ataxic neuropathy ophthalmoplegia M-protein agglutination disialosyl antibodies (CANOMAD)
• Guillain-Barré syndrome
• Hepatic neuropathy
• HIV-related neuropathy
• Multiple myeloma
• Osteosclerotic myeloma
• POEMS syndrome
• Uremic neuropathy
• Vitamin B12 deficiency

• Distal CIDP
• Anti-MAG IgM neuropathy
• Diabetic neuropathy
• Hereditary neuropathies
• POEMS syndrome
• Vasculitic neuropathy

• Focal/multifocal CIDP
• Diabetic radiculopathy/plexopathy
• Entrapment neuropathies
• Hereditary neuropathy with liability to pressure palsies (HNPP)
• Multifocal motor neuropathy (MMN)
• Neuralgic amyotrophy
• Peripheral nerve tumors
• Vasculitic neuropathy

• Motor CIDP
• Hereditary motor neuropathies
• Inflammatory myopathies
• Motor neuron disease
• Neuromuscular junction disorders syndrome)

• Sensory CIDP
• Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS)
• Chronic immune sensory polyradiculopathy (CISP)
• Dorsal column lesions
• Hereditary sensory neuropathies
• Idiopathic sensory neuropathy
• Sensory neuronopathy
• Toxic neuropathies

Management

• Early treatment is IMPORTANT to cease the immune attack against the myelin sheath of peripheral nerves, which in turn minimizes secondary axonal degeneration [25]

• Once symptoms stabilize after initial therapy → begin maintenance therapy to promote remission and prevent relapse

Intravenous immune globulin (IVIG)

• Indicated when rapid response is a priority

• Easier to administer than plasma exchange

• Dosage:
• 2 g/kg infused over 2 to 5 days (e.g., 0.5 g/kg/day for four days)
• Repeat IVIG 1 g/kg every 3 weeks for 2-3 months

• Follow-up
• If patients respond well → taper IVIG to 1 g/kg or even 0.4 g/kg per dose in 1-2 days

• Adverse effects:
• Headache
• Nausea
• Aseptic meningitis
• Acute renal failure
• Rash

Plasma exchange

• Compared to IVIG, plasma exchange shows similar effectiveness but is less convenient to administer and more expensive

• Only available at specialized centers and required venous access

• Dosage:
• 4-6 exchanges over 8-10 days then decrease to one exchange every 3-4 weeks

• Follow up:
• Reevaluate routinely, if symptoms occur between exchanges → adjust the schedule accordingly

• Adverse effects:
• Hypotension
• Sepsis
• Catheter-related complications

Glucocorticoids

• Indicated in patients with chronic CIDP due to its effectiveness at achieving long-term remission [26]

• Dosage:
• Pulse usage is more preferred than daily dose [39]
• IV methylprednisolone (1000 mg/day) for three days, then 1000 mg one day a week for 04 weeks [22], or
• Oral dexamethasone 40 mg for four consecutive days once a month [39], or
• Oral prednisone 600 mg once a week [24]

• Follow-up:
• Evaluate up to 8 weeks to decide whether there is a treatment response
• If symptoms stabilize → begin to taper glucocorticoids therapy

• Adverse effects:
• Cushingoid syndrome
• Aseptic necrosis of the femoral or humeral heads
• Osteoporosis
• Diabetes
• Hypertension

Immunosuppressive agents

• Indicated when glucocorticoids are contraindicated and for patients with refractory CIDP

• The non-exhaustive list of immune-modulator drugs that have been used to treat CIDP:
• Azathioprine
• Cyclophosphamide
• Cyclosporine
• Methotrexate
• Rituximab
• Tacrolimus
• Autologous hematopoietic stem cell transplantation

• Azathioprine and cyclophosphamide are the most commonly used medications on this list

• While those agents are promising, larger clinical trials are needed to further investigate their efficacy in CIDP

Responses to therapy assessment

Frequency of follow-ups

• Depends on which therapy and which stage of the disease

• Typically at least every three months since the initial dose or the last regimen adjustment, then adapt to patients’ clinical scenarios (e.g., shorten intervals for whose CIDP becomes worse, yearly clinical assessment for patients in remission)

Objective tools

• Exclusively relying on the subjective clinical assessment is associated with the prolongation of ineffective/inappropriate regimens and with the excessive treatment of CIDP [1]

Table 1: CIDP objective assessment tools

Prognosis

• ~2/3 of patients with CIDP respond to the starting dose of any single standard therapy (IVIG, glucocorticoids, and plasma exchange)

• ~10-15% of them are resistant to all of these [12]

• ~30% of patients with CIDP will achieve cure or remission

Further Reading

1. European Academy of Neurology/Peripheral Nerve Society guideline on diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy: Report of a joint Task Force—Second revision

2. Chronic Inflammatory Demyelinating Polyradiculoneuropathy: Five New Things

3. Chronic Inflammatory Demyelinating Polyradiculoneuropathy at StarPearls Publishing

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