Acute inflammatory demyelinating polyradiculoneuropathy (ORPHA:98916)
A rare inflammatory neuropathy belonging to the clinical spectrum of Guillain-Barré syndrome (GBS).
Epidemiology
Overall annual incidence of GBS is estimated at between 1/91,000 and 1/55,000. AIDP accounts for around 90% of GBS cases in Europe and North America and thus the term GBS is often synonymous with AIDP in Western countries. The disease occurs in patients of all ages and men are affected about 1.5 times more often than women.
Clinical description
The clinical course of AIDP is divided into three phases. The first phase (lasting a few weeks) is characterized by rapidly progressive muscle weakness (usually appearing first in the feet and progressing upwards). It is symmetrical and may cause acute neuromuscular paralysis. Sensory disturbances (tingling and numbness), intense pains, and cramps may also occur. Other sites involved may include the respiratory muscles (leading to acute respiratory failure, with 20-30% of patients needing mechanical ventilation), the deglutition muscles (leading to life-threatening aspiration) and the eye muscles (leading to ophthalmoplegia). Deep-tendon reflexes may be decreased or absent. During the second phase (variable duration), symptoms become stable but other manifestations (cardiac arrhythmias, hyper/hypotension and gastric dysmotility) may occur. During the third (recovery) phase, lasting a few months or longer, symptoms slowly regress. Many patients have residual findings (weakness, sensory disturbances, fatigue or pain) for many months or even years.
Etiology
In the majority of cases, an infectious disease precedes the onset of limb weakness, with Campylobacter jejuni infection being the most frequent initiating event. Cytomegalovirus, Epstein-Barr virus, Mycoplasma pneumoniae, and Haemophilus influenza have also been implicated. Onset of AIDP has also been reported after vaccination and surgical intervention. Although the exact pathological mechanisms remain to be discovered, AIDP is associated with activated macrophage infiltration of myelin sheaths, leading to myelin damage and demyelination. Other immunological mechanisms are also likely to play a role.
Diagnostic methods
Diagnosis is based on the clinical picture and can be difficult to establish. Lumbar puncture and cerebrospinal fluid (CSF) examination should be performed and electromyography can be helpful for confirming the diagnosis and identifying the GBS subtype: AIDP, or the axonal (AMAN, AMSAN) forms (see these terms).
Differential diagnosis
The differential diagnosis is wide and includes drug-induced neuropathy, critical illness polyneuropathy, carcinomatosis, metabolic disturbances, acute rhabdomyolysis, and cord and spinal nerve root compression or inflammation. Porphyria, vasculitis, diphtheria,, myasthenia gravis, botulism, polymyositis, dermatomyositis, brainstem encephalitis, meningitis, transverse myelitis, poliomyelitis (see these terms) as well as vitamin B1 deficiency may also be considered.
Management and treatment
Optimal care from a multidisciplinary team providing intensive-care facilities is essential for management. Treatment consists of rapid administration of intravenous immunoglobulin (IVIg) or plasma exchange. Physiotherapy and rehabilitation are important.
Prognosis
GBS patients have a variable prognosis: it is estimated that around 50% of patients recover completely or have only minor sequelae, 20% are unable to walk after 6 months and 3% die. Multiple clinical, electrophysiological, serological and laboratory factors have been identified as predictors of a poor outcome. Fatigue and endurance intolerance may persist for years.

                            Last update: 
                            December 2009


                            - Expert reviewer(s): 
                            Pr P.A. [Pieter] VAN DOORN