Electrophysiologic studies in the Guillain-Barré syndrome: effects of plasma exchange and antibody rebound

Therapeutic apheresis in neurology critical care

Therapeutic apheresis has been widely accepted in the treatment of neurological disorders that are understood to be mediated by humoral and/or cellular immunity. The clinical presumption is that well-established and/or unknown insults cause damage to nerves or their myelin sheaths. The rationale for apheresis treatments for these neurological disorders relates to removal of offending immune (or other) mediators, thus blunting the attack and permitting recovery of nerve and/or myelin. This review will concentrate on the role of therapeutic apheresis, in particular therapeutic plasma exchange, in neurological disorders that may frequently be seen by intensivists.

Guillain-Barré syndrome: epidemiology, pathophysiology and management

Guillain-Barré syndrome (GBS) is clinically defined as an acute peripheral neuropathy causing limb weakness that progresses over a time period of days or, at the most, up to 4 weeks. GBS occurs throughout the world with a median annual incidence of 1.3 cases per population of 100 000, with men being more frequently affected than women. GBS is considered to be an autoimmune disease triggered by a preceding bacterial or viral infection. Campylobacter jejuni, cytomegalovirus, Epstein-Barr virus and Mycoplasma pneumoniae are commonly identified antecedent pathogens. In the acute motor axonal neuropathy (AMAN) form of GBS, the infecting organisms probably share homologous epitopes to a component of the peripheral nerves (molecular mimicry) and, therefore, the immune responses cross-react with the nerves causing axonal degeneration; the target molecules in AMAN are likely to be gangliosides GM1, GM1b, GD1a and GalNAc-GD1a expressed on the motor axolemma. In the acute inflammatory demyelinating polyneuropathy (AIDP) form, immune system reactions against target epitopes in Schwann cells or myelin result in demyelination; however, the exact target molecules in the case of AIDP have not yet been identified. AIDP is by far the most common form of GBS in Europe and North America, whereas AMAN occurs more frequently in east Asia (China and Japan). The prognosis of GBS is generally favourable, but it is a serious disease with a mortality of approximately 10% and approximately 20% of patients are left with severe disability. Treatment of GBS is subdivided into: (i) the management of severely paralysed patients with intensive care and ventilatory support; and (ii) specific immunomodulating treatments that shorten the progressive course of GBS, presumably by limiting nerve damage. High-dose intravenous immunoglobulin (IVIg) therapy and plasma exchange aid more rapid resolution of the disease. The predominant mechanisms by which IVIg therapy exerts its action appear to be a combined effect of complement inactivation, neutralisation of idiotypic antibodies, cytokine inhibition and saturation of Fc receptors on macrophages. Corticosteroids alone do not alter the outcome of GBS.

Dissociation between titer of anti-ganglioside antibody and severity of symptoms in a case of Guillain-Barré syndrome with treatment-related fluctuation

Since plasma exchange (PE) and intravenous immunoglobulin (i.v.Ig) have been widely used in treatment for Guillain-Barré syndrome (GBS), early relapse and treatment-related fluctuation have been a potential problem, but little is known about the mechanism of relapse and fluctuation. We describe a patient who had GBS with treatment-related fluctuation. A 37-year-old Japanese man exhibited acute distal-dominant weakness in upper limbs after upper respiratory infection. His cranial nerve system was normal and muscle weakness was limited to upper limbs. Anti-GT1a IgG was strongly positive and anti-GQ1b IgG was also detected in his serum. Muscle weakness responded well to double-filtration plasmapheresis (DFPP) followed by i.v.Ig, but relapsed 45 days after the initial treatment. Although repeated treatments were effective, the patient showed additional minor deterioration twice. Motor nerve conduction velocities (MCVs) corresponded to the muscle weakness, but elevated level of cerebrospinal fluid (CSF) protein remained and anti-ganglioside antibody titers steadily decreased throughout the clinical course. These findings indicate that the clinical fluctuation was not due to changes in the production of anti-ganglioside antibodies but presumably to the transient beneficial effects of DFPP/i.v.Ig and the outlasting inflammatory response in peripheral nerves.

Anti-GM1, anti-central myelin proteins, and anti-cardiolipin autoantibodies during plasma-exchange in Guillain-Barré syndrome (GBS)

We measured the autoantibodies to GM1, central myelin proteins, and cardiolipin in 30 GBS patients using sensitive ELISA and Western blot techniques. The sequential modifications of titers during plasma-exchange (PE) and at follow-up were investigated in 15 patients. In pretreatment sera, we found significantly increased antibody titers to GM1 (37% of the patients), central myelin proteins (28%), and cardiolipin (21%). Seventeen patients out of 29 (58%) presented increased IgG or IgM antibody to at least one of the antigens considered as compared to 10 out of 70 controls (14%, P = 0.00001). By Western blot, IgG or IgM antibodies reactive with the triton insoluble fraction of central myelin were observed in 19 out of 28 GBS patients (67%). The follow-up measurements during and after PE showed a declining autoantibody titer in 10 out of 15 patients. However, in the remaining 5 GBS patients, we observed a persistently elevated titer or an increase from baseline values occurring during or after PE and reaching a peak. In 2 of the 5 patients, the titer peak preceded a clinical re-exacerbation. The presence of a persistently elevated or an increasing autoantibody titer during treatment with PE merits further investigation and may help to clarify the pathogenesis of GBS and improve its treatment.

Pathogenesis of Guillain-Barré syndrome

Recent neurophysiological and pathological studies have led to a reclassification of the diseases that underlie Guillain-Barré syndrome (GBS) into acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor and sensory axonal neuropathy (AMSAN) and acute motor axonal neuropathy (AMAN). The Fisher syndrome of ophthalmoplegia, ataxia and areflexia is the most striking of several related conditions. Significant antecedent events include Campylobacter jejuni (4-66%), cytomegalovirus (5-15%), Epstein-Barr virus (2-10%), and Mycoplasma pneumoniae (1-5%) infections. These infections are not uniquely associated with any clinical subtype but severe axonal degeneration is more common following C. jejuni and severe sensory impairment following cytomegalovirus. Strong evidence supports an important role for antibodies to gangliosides in pathogenesis. In particular antibodies to ganglioside GM1 are present in 14-50% of patients with GBS, and are more common in cases with severe axonal degeneration associated with any subtype. Antibodies to ganglioside GQ1b are very closely associated with Fisher syndrome, its formes frustes and related syndromes. Ganglioside-like epitopes exist in the bacterial wall of C. jejuni. Infection by this and other organisms triggers an antibody response in patients with GBS but not in those with uncomplicated enteritis. The development of GBS is likely to be a consequence of special properties of the infecting organism, since some strains such as Penner 0:19 and 0:41 are particularly associated with GBS but not with enteritis. It is also likely to be a consequence of the immunogenetic background of the patient since few patients develop GBS after infection even with one of these strains. Attempts to match the subtypes of GBS to the fine specificity of anti-ganglioside antibodies and to functional effects in experimental models continue but have not yet fully explained the pathogenesis. T cells are also involved in the pathogenesis of most or perhaps all forms of GBS. T cell responses to any of three myelin proteins, P2, PO and PMP22, are sufficient to induce experimental autoimmune neuritis. Activated T cells are present in the circulation in the acute stage, up-regulate matrix metalloproteinases, cross the blood-nerve barrier and encounter their cognate antigens. Identification of the specificity of these T cell responses is still at a preliminary stage. The invasion of intact myelin sheaths by activated macrophages is difficult to explain according to a purely T cell mediated mechanism. The different patterns of GBS are probably due to the diverse interplay between antibodies and T cells of differing specificities.

Extracorporeal antibody elimination in neuroimmunological diseases

Extracorporeal procedures for the elimination of autoantibodies are an important therapeutic option in various neuroimmunological diseases, especially those with neuromuscular involvement. Recent advances with the development of selective apheresis methods have given extracorporeal therapeutic procedures a new perspective. In this article, we review the therapeutic use of plasma exchange and immunoadsorption therapy in different neuroimmunological diseases.

[Fluctuations in Guillain-Barré syndrome related with intravenous human immunoglobulin (triphasic course): case report]

The authors report the case of a patient with severe Guillain-Barré syndrome (tetraplegic and on mechanical ventilation), that was treated with intravenous immunoglobulin (IVIg), 2 g/Kg. At first, there was clinical improvement, followed by clinical deterioration two weeks later. On the second course of IVIg there was, again, clinical improvement and then deterioration, 65 days after treatment. Finally, on the third course of treatment definitive recovery was achieved and no more relapses happened so far (three years after the treatment). The authors review the literature about fluctuations related to treatment with IVIg. Conclusions are that these patients should be closely observed during the first weeks after IVIg treatment, and that further studies are still necessary to elaborate alternative protocols on the prevention of these cases.

Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is viewed as a reactive, self-limited, autoimmune disease triggered by a preceding bacterial or viral infection. Campylobacter jejuni, a major cause of bacterial gastroenteritis worldwide, is the most frequent antecedent pathogen. It is likely that immune responses directed towards the infecting organisms are involved in the pathogenesis of GBS by cross-reaction with neural tissues. The infecting organism induces humoral and cellular immune responses that, because of the sharing of homologous epitopes (molecular mimicry), cross-react with ganglioside surface components of peripheral nerves. Immune reactions against target epitopes in Schwann-cell surface membrane or myelin result in acute inflammatory demyelinating neuropathy (85% of cases); reactions against epitopes contained in the axonal membrane cause the acute axonal forms of GBS (15% of cases). Care for such patients may be challenging, yet the prognosis overall is favourable. Optimal supportive care and anticipation and prevention of complications are the mainstay of therapy. Admission to the intensive-care unit is necessary in 33% of patients who require intubation and assisted ventilation. Immunomodulation with infusions of IgG or plasma exchange treatments foreshorten the disease course.

Guillain-Barré syndrome. A severe case calling for intensive treatment

Guillain-Barré syndrome is a relatively common disease with a low mortality rate. Early recognition and institution of treatment lead to a more favorable outcome, especially in more severe cases. Because the patient's condition may deteriorate rapidly, it is crucial to keep the patient in the hospital until his or her condition is confirmed to be stable. Plasmapheresis improves symptoms when instituted within 2 weeks of symptom onset. Treatment with high-dose intravenous immune globulin produces similar results. Speed of recovery varies, but often occurs in a few weeks or months.

Electrophysiological studies in Guillain-Barré syndrome: correlation with antibodies to GM1, GD1B and Campylobacter jejuni

A retrospective study of 50 patients with Guillain-Barré syndrome (GBS) correlated analysis of serial motor nerve conduction studies with the presence of antibodies to Campylobacter jejuni, GM1 and GD1b, determined by ELISA. GBS patients with antibodies to C. jejuni (n = 8), GM1 (n = 4), or GD1b (n = 4) showed electrophysiological features suggestive of demyelination with prolonged distal motor latencies and temporal dispersion/conduction block similar to GBS patients without these specific antibodies. Three of 50 GBS patients had poor recovery with inability to walk at 1 year after onset of symptoms. All three patients had antibodies to C. jejuni, but not to GM1 or GD1b. Although later on in the clinical course distal motor responses were absent in two of these patients, reflecting extensive axonal degeneration, early nerve conduction studies showed findings suggestive of demyelination. We suggest that demyelination of peripheral nerve may be the initial disease mechanism in GBS independent of the presence of antibodies to C. jejuni, GM1 or GD1b.

Immunopathogenesis and treatment of the Guillain-Barré syndrome--Part II

In the second part of our review the role of antecedent infections in the pathogenesis of GBS is discussed. The association with Campylobacter jejuni (C. jejuni) is highlighted and the concept of molecular mimicry, i.e., sharing of epitopes between microbes and peripheral nerve, explained. Alternative mechanisms to relate an infection with the immune-mediated neuropathy are elaborated. Current therapies of the GBS include plasma exchange, high-dose intravenous immunoglobulins, and supportive treatment directed to secondary complications. Published therapeutic trials are reviewed and future approaches are outlined. Principles of general care are also summarized.

Antigalactocerebroside antibody increases demyelination in adoptive transfer experimental allergic neuritis

There is suggestive but inconclusive evidence for a contribution of T cells and antimyelin antibodies to the pathogenesis of the Guillain-Barré polyneuropathy. We have studied the potential synergism of cellular and humoral immunity in the adoptive transfer model of EAN. EAN was induced in Lewis rats by injecting varying doses of P2 peptide (SP26)-sensitized T lymphocytes. Disease severity was dose-dependent. The addition of intravenous GC-AB to a subclinical dose of SP26-sensitized T cells resulted in overt clinical disease and markedly enhanced demyelination. Intravenous injection of antibody alone had no effect. We conclude that activated neuritogenic T cells, while entering into peripheral nerves, alter the blood-nerve barrier, which gives circulating demyelinating antibodies access to the endoneurium. The observations support the concept of a synergistic role of T-cell autoimmunity and humoral responses in the inflammatory demyelination of Lewis rat EAN.

The acute paralysis in Guillain-Barré syndrome is related to a Na+ channel blocking factor in the cerebrospinal fluid

The effect of cerebrospinal fluid (CSF) from patients with severe polyradiculoneuritis (Guillain-Barré syndrome, GBS) on voltage-dependent Na+ channels of myoballs was studied. The transient Na+ currents, elicited by repetitive stimulation at 1 Hz, were inhibited by the CSF from most of the GBS patients to 10%-40% the control value. The inhibition was complete in about 5 s and was fully reversible. Such inhibition was never seen with control CSF. The blocking property of the CSF from GBS patients was lost after the number of cells and the protein content had been lowered by means of a clinical filtration technique for cerebrospinal fluid. The results demonstrate that in Guillain-Barré syndrome blocking factors of Na+ channels are present in the CSF, impairing neuron impulse conduction, and thereby causing muscular weakness and sensory disturbances in the affected patient.