Electrodiagnosis aids in the diagnosis. the most common subtype.[6,7] The picture is intermediate when we look at other population. In Indian series the incidence of AIDP and AMAN are virtually equal although AMAN is more common in younger patients.[8] There seems to be a slight preponderance of AIDP in studies by Guptaet al[9] and by Meena et al (unpublished data from NIMS, Hyderabad). Available Indian literature indicates a peak incidence between JuneJuly and SeptOctober.[10] In western countries, GBS is common in the 5thdecade,[11] but in India it occurs more commonly at a younger age.[10,12] GBS is equally common in men and women and can occur at any age. There is a male preponderance among the hospitalized population.[10,12] == Clinical Features == Most often an unremarkable infection, such as upper respiratory infection, often predates the onset of GBS by 14 days.[2,5] Many antecedent infections have been identified, includingCampylobacter jejuni, cytomegalovirus (CMV),Mycoplasma pneumonia, EpsteinBarr virus, influenza virus, JEV.[13,14] Surgery, immunization, and parturition have also been associated with GBS. GBS usually begins abruptly with distal, relatively symmetrical onset of paraesthesias and quickly followed by progressive limb weakness. Progression is rapid, with 50% of patients reaching clinical nadir by 2 weeks and more than 90% by 4 weeks. The current diagnostic criteria include <4 weeks of progression to clinical nadir. Approximately 80%90% of patients with GBS become nonambulatory during the illness.[15,16] Pain is prominent in 50% of patients.[16,17] Neurological examination is characterized by distal and often proximal, relatively symmetrical, weakness. Although GBS is essentially a motor neuropathy, sensory dysfunction is seen PI-103 Hydrochloride in a few patients. It is seen more in a demyelinating form of GBS.[12,18] Sensory examination is often normal in the early phase of disease. Facial or pharyngeal weakness is commonly seen in GBS. Diaphragmatic weakness due to phrenic nerve involvement is also common. Approximately one third of hospitalized GBS patients require mechanical ventilation due to respiratory muscle or oropharyngeal weakness.[18,19] Tachycardia is common Rabbit Polyclonal to GAB4 but more serious autonomic PI-103 Hydrochloride nervous system dysfunction may occur, including life-threatening arrhythmias, hypotension, hypertension, and gastrointestinal dysmotility. The incidence is between 27% and 55% and is more common in demyelinating than axonal form.[12,20] == Pathogenesis == Major advances have been made in understanding the mechanisms of some of the subtypes. The histological appearance of the AIDP subtype resembles experimental autoimmune neuritis, which is predominantly caused by T cells directed against peptides from the myelin proteins P0, P2, and PMP22. The role of T-cell-mediated immunity in AIDP remains unclear and there is evidence for the involvement of antibodies and complement. Strong evidence now exists that axonal subtypes of GuillainBarr syndrome, acute motor axonal neuropathy (AMAN), and acute motor and sensory axonal neuropathy (AMSAN), are caused by antibodies to gangliosides on the axolemma that target macrophages to invade the axon at the node of Ranvier. About a quarter of patients with GuillainBarr syndrome have had a recent C.jejuniinfection, and axonal forms of the disease are especially common in these people. The lipo-oligosaccharide from the C.jejunibacterial wall contains ganglioside-like structures and its injection into rabbits induces a neuropathy that resembles acute motor axonal neuropathy.[2123] Antibodies to GM1, GM1b, GD1a, and GalNac-GD1a are in particular implicated in acute motor axonal neuropathy and, with the exception of GalNacGD1a, in acute motor and sensory axonal neuropathy. == Diagnosis == Progressive weakness in both upper and lower extremities within 4 weeks along with areflexia is essential requirement for the diagnosis. Supportive ancillary testing for GBS includes CSF analysis and electrodiagnostic testing, both of which may be normal in the early phase of GBS. The limitations of ancillary testing in the early phase combined with the importance of prompt treatment of GBS mandates that the clinician at times make the diagnosis based solely on history and examination. An elevated CSF protein concentration (with normal cell count) is only found on initial CSF analysis in 50% of patients; elevated CSF protein concentration occurs in more than 90% of patients at the peak of the disease. CSF pleocytosis is an important red flag, which raises the question of infectious (HIV, CMV, Lyme, sarcoid), carcinomatous, or lymphomatous polyradiculoneuropathy [Table 2]. == Table 2. == GuillianBarr syndromered fl ags raising other diagnostic possibilities == Electrodiagnosis == Electrodiagnostic (EDX) testing is performed to support the clinical impression. EDX testing of GBS patients often demonstrates features of demyelination, such as temporal dispersion, significantly slow conduction PI-103 Hydrochloride velocities, and prolonged distal and F-wave latencies.[24] Electrodiagnostic.