Idiopathic dysautonomia treated with intravenous gammaglobulin

Orthostatic hypotension: A review

Orthostatic hypotension, defined by a drop in blood pressure of at least 20mmHg for systolic blood pressure and at least 10mmHg for diastolic blood pressure within 3minutes of standing up, is a frequent finding, particularly in elderly patients. It is associated with a significant increase in morbidity and mortality. Although it is often multifactorial, the first favoring factor is medications. Other etiologies are divided in neurogenic orthostatic hypotension, characterized by autonomic failure due to central or peripheral nervous system disorders, and non-neurogenic orthostatic hypotension, mainly favoured by hypovolemia. Treatment always requires education of the patient regarding triggering situations and physiological countermanoeuvers. Pharmacological treatment may sometimes be necessary and mainly relies on volume expansion by fludrocortisone and/or a vasopressor agents such as midodrine. There is no predefined blood pressure target, the goal of therapy being the relief of symptoms and fall prevention.

Autoimmune autonomic ganglionopathy manifesting as acute-onset orthostatic hypotension in a patient undergoing peritoneal dialysis

Orthostatic hypotension is an important complication in the management of patients receiving dialysis therapy. As for the orthostatic hypotension caused by decreased peripheral artery resistance, diabetic neuropathy and amyloidosis are the two main causes of hypotension in dialysis patients. However, some patients develop orthostatic hypotension that is caused by dysfunction of the autonomic nervous system, not by diabetic or amyloidosis-related neuropathy. We herein present a case of a 56-year-old man with a 17-year history of peritoneal dialysis therapy, who developed acute-onset orthostatic hypotension accompanied by hypohidrosis and erectile dysfunction. Because serum autoantibodies to ganglionic nicotinic acetylcholine receptor were detected, he was diagnosed with autoimmune autonomic ganglionopathy (AAG). He was treated with high-dose immunoglobulin therapy (0.6 g per kg of body weight per day) for 5 consecutive days, which resulted in a gradual improvement in dizziness. Two months after the onset of AAG, he could discontinue vasopressors (fludrocortisone acetate and midodrine hydrochloride) and continued maintenance dialysis therapy without the use of vasopressors. This case indicates that physicians should consider autonomic neuropathy including AAG as a differential diagnosis when they encounter dialysis patients with orthostatic hypotension.

Autonomic neuropathies

PURPOSE OF REVIEW

This article focuses on the most prevalent forms of autonomic neuropathies, but also discusses conditions such as focal and dysfunctional syndromes (altered autonomic function in the absence of structural lesions). The goal of this review is to allow the reader to promptly recognize these disorders, identify potentially reversible or treatable causes, and implement the appropriate treatment as well as supportive care.

RECENT FINDINGS

Secondary forms of autonomic neuropathies (eg, diabetes mellitus, amyloidosis) are much more common than primary forms, of which autoimmune ganglioneuropathies represent a major component. However, the spectrum of the latter is continuously evolving and has diagnostic and therapeutic implications. Testing modalities such as autonomic testing, serum autoimmune antibody testing, and skin biopsies are becoming more widely available.

SUMMARY

Autonomic neuropathies are relatively common conditions, and, because of the prognostic implications as well as impact on patient quality of life, they should be promptly recognized and treated aggressively. Testing is critical as other conditions may mimic autonomic neuropathies. Treatment is symptomatic in many cases, but specific therapies are also available in selected autonomic neuropathies.

Anti-neuronal antibodies in acute pandysautonomia

We encountered two patients with acute pandysautonomia who subacutely exhibited extensive autonomic dysfunction after antecedent infections. Although these patients had been suffering from autonomic disturbance for several months, they both had a good clinical course after plasma exchange and intravenous immunoglobulin therapy. Thin-layer chromatography (TLC)-immunostaining did not demonstrate any antibodies against gangliosides, but immunoblot analysis showed antibodies against a neuroblastoma cell line, SH-SY5Y, in serum samples. Furthermore, ganglionic acetylcholine receptor autoantibodies were detected in one patient. These findings suggest that neuronal antibodies against the autonomic nervous system play an important role in the pathogenesis of acute pandysautonomia.

Efficacy of immunotherapy in seropositive and seronegative putative autoimmune autonomic ganglionopathy

OBJECTIVE

To evaluate the efficacy of immunotherapy in the treatment of patients with seropositive and seronegative putative autoimmune autonomic ganglionopathy (AAG) using validated autonomic function tests and instruments.

BACKGROUND

AAG is an immune-mediated disorder characterized by prominent and selective involvement of autonomic nerve fibers or ganglia. Treatment with i.v. immunoglobulin (IVIg) or plasma exchange (PE) has been reported to be effective in single case reports.

METHODS

We studied six patients, four with seropositive and two with seronegative putative AAG, who underwent autonomic function tests and completed two validated questionnaires, to assess autonomic symptoms before and after immunomodulatory treatment. Patients were treated with standard doses of IVIg, PE, or immunosuppressants in a specific sequential therapy protocol depending on clinical response.

RESULTS

Of the six patients (all women, mean ages 49.3 +/- 10.6 years), four patients were ganglionic (alpha3) AChR autoantibody positive and two were autoantibody negative. All patients showed clinical improvement after treatment. Sudomotor function assessed by quantitative sudomotor axon reflex test and thermoregulatory sweat test improved in four patients after treatment.

CONCLUSIONS

Immunomodulatory treatment can be effective in both seropositive and seronegative putative autoimmune autonomic ganglionopathy. Plasma exchange or combined therapy with immunosuppressive agents should be considered in patients who do not benefit from i.v. immunoglobulin alone.

Neurological aspects of syncope and orthostatic intolerance

Sudden falling with loss of consciousness from syncope and symptoms of orthostatic intolerance are common, dramatic clinical problems of diverse cause, but cerebral hypoperfusion is the ultimate mechanism in most. Cardiac, reflex, and orthostatic hypotension are important forms to consider. Syncope must be differentiated from seizures, psychiatric events, drop attacks, and other mimics. However, factors such as syncopal induced movements, ictal bradycardia, and insufficient clinical information can confound accurate diagnosis and hamper appropriate treatment. Progress in the diagnosis, treatment, and understanding of underlying mechanisms is continually advancing.

Invited Article: Autonomic ganglia: target and novel therapeutic tool

Nicotinic acetylcholine receptors (AChR) are ligand-gated cation channels that are present throughout the nervous system. The muscle AChR mediates transmission at the neuromuscular junction; antibodies against the muscle AChR are the cause of myasthenia gravis. The ganglionic (alpha 3-type) neuronal AChR mediates fast synaptic transmission in sympathetic, parasympathetic, and enteric autonomic ganglia. Impaired cholinergic ganglionic synaptic transmission is one important cause of autonomic failure. Pharmacologic enhancement of ganglionic synaptic transmission may be a novel way to improve autonomic function. Ganglionic AChR antibodies are found in patients with autoimmune autonomic ganglionopathy (AAG). Patients with AAG typically present with rapid onset of severe autonomic failure. Major clinical features include orthostatic hypotension, gastrointestinal dysmotility, anhidrosis, bladder dysfunction, and sicca symptoms. Impaired pupillary light reflex is often seen. Like myasthenia, AAG is an antibody-mediated neurologic disorder. The disease can be reproduced in experimental animals by active immunization or passive antibody transfer. The patient may improve with plasma exchange treatment or other immunomodulatory treatment. Antibodies from patients with AAG inhibit ganglionic AChR currents. Other phenotypes of AAG are now recognized based on the results of antibody testing. These other presentations are generally associated with lower levels of ganglionic AChR antibodies. A chronic progressive form of AAG may resemble pure autonomic failure. Milder forms of dysautonomia, such as postural tachycardia syndrome, are associated with ganglionic AChR in 10-15% of cases. Since ganglionic synaptic transmission is a common pathway for all autonomic traffic, enhancement of autonomic function through inhibition of acetylcholinesterase is a potential specific therapeutic strategy for autonomic disorders. Increasing the strength of ganglionic transmission can ameliorate neurogenic orthostatic hypotension without aggravating supine hypertension. Recent evidence also suggests a potential role for acetylcholinesterase inhibitors in the treatment of postural tachycardia syndrome.

Acute motor-sensory axonal neuropathy associated with active systemic lupus erythematosus and anticardiolipin antibodies

Acute motor-sensory axonal neuropathy (AMSAN) is an axonal variant of Guillian-Barré syndrome (GBS) that presents with acute ascending quadriparesis. This has generally been described in association with Campylobacter jejuni infections or with anti-ganglioside antibodies. Known cases have shown a slow recovery and a poor prognosis. We report a case with clinical and electrophysiological evidence of AMSAN in association with active systemic lupus erythematosus (SLE) and anticardiolipin antibodies but not the other associations, with a rapid response to combination immunosuppressant and intravenous immunoglobulin (IVIg) therapy. The association between AMSAN and SLE has not been previously described. This case illustrates that early recognition and the utilization of electrophysiologic techniques may be beneficial in the diagnosis and management of GBS associated with SLE. Fulminant or rapidly progressive cases should be managed in specialized intensive care units. Combination therapy of immunosuppressants and IVIg may be beneficial in non-vasculitic axonal radiculo-neuropathies associated with SLE, resulting in good outcomes.

Dysfunction of the pupillary light reflex in experimental autoimmune autonomic ganglionopathy

Autoimmune autonomic ganglionopathy (AAG) is an antibody-mediated form of severe autonomic failure. AAG is associated with serum antibodies against ganglionic acetylcholine receptors (AChR) and appears to result from impaired synaptic transmission in autonomic ganglia. The rabbit model of experimental AAG (EAAG), induced by immunization, reproduces the cardinal features of the human disease. Pupillary dysfunction is a prominent and defining feature in both AAG and EAAG. We adapted infrared computer-assisted video pupillometry to record direct pupil light responses in control and EAAG rabbits. Offline analysis algorithms were used to determine latency, velocity and amplitude of the constriction and redilation phases of the light reflex. Following immunization, pupillary abnormalities were the earliest sign of evolving autonomic failure. EAAG rabbits showed significant reduction in velocity and amplitude of pupil constriction while redilation parameters were only mildly affected. Fatigue in pupillary constriction, evidenced by premature redilation of the pupil prior to termination of the light stimulus, was observed only in seropositive rabbits. The severity of pupillary abnormalities was significantly correlated with ganglionic AChR antibody level. In chronic EAAG, treatment with pyridostigmine produced a partial recovery of pupil function. We conclude that pupillometry is a robust and sensitive diagnostic tool to assess autonomic dysfunction, distinguish AAG from other disorders, and assess responses to therapy. In EAAG, pupillary dysfunction is partially reversible, parasympathetic pupil function is more severely compromised than sympathetic function, and fatigue of pupillary constriction may be seen. These characteristic abnormalities of the pupillary light reflex may prove to have diagnostic value.

Autonomic Peripheral Neuropathy

Most generalized peripheral polyneuropathies are accompanied by clinical or subclinical autonomic dysfunction. There is a group of peripheral neuropathies in which the small or unmyelinated fibers are selectively targeted. In these neuropathies, autonomic dysfunction is the most prominent manifestation. The features associated with an autonomic neuropathy include impairment of cardiovascular, gastrointestinal, urogenital, thermoregulatory, sudomotor, and pupillomotor autonomic function.

Diagnosis and Treatment of Chronic Immune-mediated Neuropathies

The chronic autoimmune neuropathies are a diverse group of disorders, whose diagnosis and classification is based on the clinical presentations and results of ancillary tests. In chronic inflammatory demyelinating polyneuropathy, controlled therapeutic trials demonstrated efficacy for intravenous gamma-globulins, corticosteroids, and plasmaphereis. In multifocal motor neuropathy, intravenous gamma-globulins have been shown to be effective. In the other immune-mediated neuropathies, there are no reported controlled therapeutic trials, but efficacy has been reported for some treatments in non-controlled trials on case studies. Choice of therapy in individual cases is based on reported efficacy, as well as severity, progression, coexisting illness, predisposition to developing complications, and potential drug interactions.

Immune-mediated autonomic neuropathies

Improved recognition and availability of noninvasive testing of autonomic disorders has prompted a better understanding of disease mechanisms of some disease forms, especially potentially treatable immune-mediated autonomic neuropathies. Development is acute, subacute, or less commonly chronic. Autonomic involvement is common and an important cause of morbidity and mortality in Guillain-Barré syndrome. Acute autonomic neuropathy can affect parasympathetic, sympathetic, and enteric nerves or neurons and is associated with antibodies to ganglionic nicotinic acetylcholine receptors. These antibodies appear to be causative based on a rabbit immunization model and serum transfer studies from patients and animals. Other important immune autonomic disorders discussed include Lambert-Eaton myasthenic syndrome, some forms of orthostatic intolerance, chronic autonomic neuropathy, and Sjögren syndrome. Paraneoplastic autonomic disorders are clinically indistinguishable and associated with various overlapping antibody associations, including anti-Hu (ANNA-1), ganglionic acetylcholine receptors, CRMP-5, and PCA-2.

Plasma exchange for primary autoimmune autonomic failure

We report on a patient with long-standing severe autonomic failure that affected his sympathetic and parasympathetic nervous systems. Antibodies against the ganglionic acetylcholine receptors were detected in the serum. Removal of the antibodies by means of plasma exchange resulted in a dramatic clinical improvement.

Autonomic peripheral neuropathy

The autonomic neuropathies are a group of disorders in which the small, lightly myelinated and unmyelinated autonomic nerve fibres are selectively targeted. Autonomic features, which involve the cardiovascular, gastrointestinal, urogenital, sudomotor, and pupillomotor systems, occur in varying combination in these disorders. Diabetes is the most common cause of autonomic neuropathy in more developed countries. Autonomic neuropathies can also occur as a result of amyloid deposition, after acute infection, as part of a paraneoplastic syndrome, and after exposure to neurotoxins including therapeutic drugs. Certain antibodies (eg, anti-Hu and those directed against neuronal nicotinic acetylcholine receptor) are associated with autonomic signs and symptoms. There are several familial autonomic neuropathies with autosomal dominant, autosomal recessive, or X-linked patterns of inheritance. Autonomic dysfunction can occur in association with specific infections. The availability of sensitive and reproducible measures of autonomic function has improved physicians' ability to diagnose these disorders.

Acute dysautonomia: complete recovery after two courses of IVIg

An 11-year-old boy presented with acute dysautonomia manifesting as severe orthostatic hypotension following fever. Serial orthostatic tests with measurement of the coefficient of variation in the R-R intervals showed improvement after one course and complete recovery after two courses of intravenous high-dose immunoglobulin therapy (IVIg). Repeated courses of IVIg should be considered to treat this disorder if spontaneous remission does not occur.

Pandysautonomie isolée subaiguë : intérêt du traitement par immunoglobulines polyvalentes

INTRODUCTION

Acute or sub-acute pure dysautonomia is uncommon. We report a case of sub-acute pure pandysautonomia with favorable outcome after intravenous immunoglobulin therapy.

CASE REPORT

A 29-year-old right-handed student, with an uneventful medical history presented, for one month, bilateral loss of visual acuity and digestive disorders, associating diarrhea, vomiting and anorexia. Physical examination revealed bilateral intrinsec oculomotor nerve palsy, a dryness syndrome and severe orthostatic hypotension. Ophthalmologic examination showed bilateral diffuse parasympathic impairment associating an Argyll Robertson pupil and full pupil light reflex abolition. Elevated protein level (0.93g/l) was the only cerebrospinal fluid anomaly. Serum tests were negative for anti-gangliosides antibodies. The patient improved slowly after two series of intravenous immunoglobulin infusions.

CONCLUSION

Clinical course and laboratory findings suggest that acute or sub-acute pure pandysautonomia events are likely to be related to acute polyradiculoneuritis. Therefore intravenous polyvalent immunoglobulin infusions should be attempted, even if their efficacy needs to be confirmed.

Antiidiotypic antibodies neutralize autoantibodies that inhibit cholinergic neurotransmission

OBJECTIVE

Functional autoantibodies that inhibit M(3) muscarinic receptor (M3R)-mediated neurotransmission have been reported in patients with Sjögren's syndrome (SS) and in patients with scleroderma. Because of limited reports that intravenous immunoglobulin (IVIG) improves dysautonomia in primary SS, we investigated whether IVIG neutralizes the effect of anti-M3R antibodies on colon smooth muscle contractions, in an in vitro functional assay.

METHODS

IgG obtained from patients with primary SS, patients with rheumatoid arthritis and secondary SS, and patients with scleroderma was tested, before and after coincubation with equimolar amounts of IVIG or its F(ab')(2) and Fc fractions, for the ability to inhibit carbachol-evoked colon smooth muscle contractions. In addition, patient IgG was passed through an IVIG F(ab')(2) column, and unretained IgG was tested for functional activity on colon smooth muscle strips. Purified IgG obtained from healthy adults was also examined for a neutralizing effect on anti-M3R antibody activity.

RESULTS

Inhibition of colon contractions was mediated by the Fab fraction of patient IgG. Coincubation of IgG from the 3 patient groups with IVIG or its F(ab')(2) fragment neutralized anti-M3R antibody-mediated inhibition of cholinergic smooth muscle contractions. Preabsorption of patient IgG with Sepharose-bound IVIG F(ab')(2) removed the anti-M3R inhibitory activity. In addition, purified IgG from each of 4 healthy adults neutralized the functional autoantibodies.

CONCLUSION

Anti-M3R antibody activity does not require receptor crosslinking. Antiidiotypic antibodies present in pooled IgG neutralize patient IgG-mediated inhibition of M3R cholinergic neurotransmission, providing a rationale for IVIG as a treatment of autonomic dysfunction in patients with SS and patients with scleroderma. Furthermore, antiidiotypic antibodies in healthy individuals may prevent the emergence of pathogenic anti-M3R autoantibodies.

Syncope and orthostatic intolerance

Syncope and orthostatic intolerance remain common and significant clinical problems with many undocumented, misdiagnosed, or cryptogenic cases. Careful clinical assessment and application of advancing laboratory support can further improve diagnosis and treatment. Despite the depth of existing research into these common problems, many underlying mechanisms remain unproven.

The spectrum of autoimmune autonomic neuropathies

We analyzed the clinical characteristics of 18 patients (13 female, 5 male) who had autoimmune autonomic neuropathy (AAN) and ganglionic acetylcholine receptor (AChR) autoantibodies. Mean age was 61.4 years (standard deviation, 12.0 years). Ten patients had subacute symptom onset, six with an antecedent event. Eight patients had chronic AAN, characterized by insidious symptom onset, without antecedent event, and gradual progression. A majority of patients with high antibody values (>1.00 nmol/L) had a combination of sicca complex (marked dry eyes and dry mouth), abnormal pupillary light response, upper gastrointestinal symptoms, and neurogenic bladder. Chronic AAN segregated into two subgroups. One subgroup (N = 4) had low antibody titer (0.09 +/- 0.01 nmol/L) and a paucity of cholinergic symptoms. It was indistinguishable from pure autonomic failure. The other subgroup (N = 4) had high antibody titer (11.6 +/- 2.08 nmol/L), sicca complex, abnormal pupils, and neurogenic bladder; three had severe upper gastrointestinal dysfunction. Higher antibody titers correlated with greater autonomic dysfunction and more frequent cholinergic dysautonomia. These observations expand the clinical spectrum of AAN to include chronic cases, some being indistinguishable from pure autonomic failure, and support the concept that ganglionic AChR antibodies are important diagnostically and pathophysiologically in acquired dysautonomia.

Autonomic dysfunction in peripheral nerve disease

Autonomic neuropathies are inherited or acquired neuropathies in which autonomic nerve fibers are selectively or disproportionately affected. Generally, sympathetic and parasympathetic fibers are both affected but there are exceptions. Acquired cases can be autoimmune; due to diabetes, amyloidosis, drugs, or toxins; or idiopathic. Autoimmune autonomic neuropathy is often subacute, sometimes associated with a neoplasm, and associated with high titers of antibody to ganglionic nicotinic acetylcholine receptor in about half of the severe cases. The molecular basis of inherited autonomic neuropathies is better known, including recent identification of the loci and genes of hereditary sensory and autonomic neuropathies types I, III, and IV. The inherited amyloid neuropathies are due to mutations of three proteins: transthyretin, apolipoprotein A1, and gelsolin. Non-invasive autonomic testing complements clinical and electrophysiological characterization of the autonomic neuropathies.

Treatment approaches for Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy

GBS and CIDP are important treatable forms of acquired peripheral neuropathies. GBS is a heterogeneous disorder representing at least five different entities. Three are predominantly motor: AIDP, AMSAN, and AMAN. Fisher syndrome and acute panautonomic neuropathy are other variants. Treatment for all of these conditions is the same and includes either plasma exchange or intravenous immunoglobulin. There is no indication that Guillain-Barré patients respond to corticosteroids. At the present time, it is uncertain if CIDP represents one or more disorders. Evidence favors a syndrome composed of more than one entity accounting for (1) clinical variations from subject-to-subject, ranging from symmetrical to focal neurologic deficits; (2) course variations from slowly progressive to step-wise, to relapsing; and, (3) laboratory variations in nerve conduction studies, spinal fluid protein, and nerve biopsy findings. CIDP patients respond to corticosteroids in contrast to those with GBS. CIDP improves with intravenous immunoglobulin and plasma exchange, paralleling the findings in GBS. Specific regimens of treatment for both GBS and CIDP are presented in this article and considerations that might influence one treatment regimen over another are discussed.

Intravenous immunoglobulin treatment in peripheral nerve disorders--indications, mechanisms of action and side-effects

This review summarizes observations of clinical use of high dose intravenous immunoglobulin G (IVIg) in regards to administration, kinetics, known or postulated mechanisms of action, and adverse reactions. Indications and value of IVIg for the treatment of various neuropathies with presumed autoimmune aetiology are examined. New knowledge that advances the understanding of the pathogenesis of the neuropathies and of the mechanisms of action of IVIg is discussed.

Human intravenous immunoglobulin preparation and virus inactivation by pasteurization and solvent detergent treatment

Human intravenous immunoglobulin (IVIG) solutions were prepared by two different methods and compared to each other. The crude immunoglobulin fraction obtained from Cohn-Oncley fractionation of plasma was further purified and subjected to virus inactivation, either by polyethylene glycol precipitation and pasteurization at 60 degrees C for 10 hours, or by ion exchange chromatography and solvent/detergent treatment. The final preparations, formulated in 5% immunoglobulin solutions were characterized by in vitro analyses of biochemical and biological properties and compared with the samples of other manufacturer's IVIG solution products. The critical properties evaluated in this study were purity, molecular intactness, and the biological functions such as Fc function and anticomplementary activity. Virus inactivation and removal by processing steps and by deliberate virucidal steps, as described above, were tested on various human pathogenic viruses, such as human immunodeficiency and experimental model viruses. The tested viruses were successfully inactivated and removed. We conclude that the intravenous immunoglobulins prepared by two different methods, as described above, provide an equivalent viral safety and quality.

Intestinal pseudo-obstruction and acute pandysautonomia associated with Epstein-Barr virus infection

We report the association of neurological and intestinal disorders with the reactivation of Epstein-Barr virus (EBV) in a child. This previously healthy 13-yr-old boy presented with pharyngitis and acute abdominal ileus. Laparotomy excluded a mechanical obstruction. Postoperatively, he suffered from prolonged intestinal obstruction, pandysautonomia, and encephalomyelitis. Histological examination of the appendix and a rectal biopsy taken 3 months after the onset showed an absence of ganglion cells (appendix) and hypoganglionosis (rectum), with a mononucleate inflammatory infiltrate in close contact with the myenteric neural plexuses. EBV-PCR was positive in the blood and cerebrospinal fluid, and in situ hybridization with the Epstein-Barr virus encoded RNA probe showed positive cells throughout the appendix wall including the myenteric area, in a mesenteric lymph node, and in the gastric biopsies. EBV spontaneous lymphocytic proliferation was noted in the blood. The serology for EBV showed previous infection but anti-early antigen antibodies were present. No immunodeficiency was found. Neurological and GI recovery occurred after 6 months of parenteral nutrition and bethanechol. The omnipresence of EBV associated with the neurointestinal symptoms suggest that the virus was the causal agent. This is the first documented case of acquired hypoganglionnosis due to EBV reactivation.

Intravenous immunoglobulin in the treatment of autoimmune neuromuscular diseases: present status and practical therapeutic guidelines

This review summarizes the current status of intravenous immunoglobulin (IVIg) in the treatment of autoimmune neuromuscular disorders and the possible mechanisms of action of the drug based on work in vivo, in vitro, and in animal models. Supply of idiotypic antibodies, suppression of antibody production, or acceleration of catabolism of immunoglobulin G (IgG) are relevant in explaining the efficacy of IVIg in myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS), and antibody-mediated neuropathies. Suppression of pathogenic cytokines has putative relevance in inflammatory myopathies and demyelinating neuropathies. Inhibition of complement binding and prevention of membranolytic attack complex (MAC) formation are relevant in dermatomyositis (DM), Guillain-Barré syndrome (GBS), and MG. Modulation of Fc receptors or T-cell function is relevant in chronic inflammatory demyelinating polyneuropathy (CIDP), GBS, and inflammatory myopathies. The clinical efficacy of IVIg, based on controlled clinical trials conducted in patients with GBS, CIDP, multifocal motor neuropathy (MMN), DM, MG, LEMS, paraproteinemic IgM anti-myelin-associated glycoprotein (anti-MAG) demyelinating polyneuropathies, and inclusion body myositis is summarized and practical issues related to each disorder are addressed. The present role of IVIg therapy in other disorders based on small controlled or uncontrolled trials is also summarized. Finally, safety issues, risk factors, adverse reactions, spurious results or serological tests, and practical guidelines associated with the administration of IVIg in the treatment of neuromuscular disorders are presented.

Autonomic neuropathies

A limited autonomic neuropathy may underlie some unusual clinical syndromes, including the postural tachycardia syndrome, pseudo-obstruction syndrome, heat intolerance, and perhaps chronic fatigue syndrome. Antibodies to autonomic structures are common in diabetes, but their specificity is unknown. The presence of autonomic failure worsens prognosis in the diabetic state. Some autonomic neuropathies are treatable. Familial amyloid polyneuropathy may respond to liver transplantation. There are anecdotal reports of acute panautonomic neuropathy responding to intravenous gamma globulin. Orthostatic hypotension may respond to erythropoietin or midodrine.

Effect of Lambert-Eaton myasthenic syndrome antibodies on autonomic neurons in the mouse

Somatic muscle weakness and autonomic symptoms characterize the autoimmune Lambert-Eaton myasthenic syndrome (LEMS). The former results from IgG autoantibody-mediated down-regulation of P/Q-type voltage-gated calcium channels at motor nerve terminals and consequent reduction in acetylcholine release; the basis for the autonomic symptoms is unknown. Using omega-conotoxins GVIA and MVIIC and omega-agatoxin IVA that block N-, Q-, and P-type channels, we investigated ex vivo the calcium channels subserving transmitter release from postganglionic parasympathetic neurons in the bladder and from postganglionic sympathetic neurons in the vas deferens of mice injected with IgG from LEMS patients or from controls. Calcium influx through N-, P-, and Q-type channels subserved transmitter release from parasympathetic and sympathetic neurons in control mice. In test mice, the component of transmitter release subserved by P-type channels was abolished by four of four LEMS IgG preparations, that subserved by Q-type channels was significantly reduced by three, and that subserved by N-type channels by one. Thus, LEMS IgG impairs transmitter release from parasympathetic and sympathetic neurons through down-regulation of one or more subtypes of voltage-gated calcium channels. The results suggest that antibody-mediated interference with specific ion channel function may also underlie autonomic dysfunction occurring in other autoimmune diseases.

Unusual recovery from acute panautonomic neuropathy after immunoglobulin therapy

A 33-year-old woman with acute idiopathic postganglionic panautonomic neuropathy experienced prompt recovery of all dysautonomic symptoms after receiving high-dose intravenous immunoglobulin therapy. Her recovery was complete within 6 months after onset of disease. This unusually rapid and complete recovery in comparison with that of historical control subjects suggests that patients with acute, severe, and widespread autonomic failure might benefit from intravenous immunoglobulin therapy.

Epstein-Barr virus--associated acute autonomic neuropathy

A 44-year-old man developed blurry vision, photosensitivity, orthostasis, constipation, and acrodysesthesias after a febrile illness. The neurologic examination and ancillary studies were consistent with a dysautonomic small fiber neuropathy. The cerebrospinal fluid (CSF) contained both Epstein-Barr virus (EBV) DNA and antibody to EBV. This is the first report of an acute autonomic neuropathy with documented EBV infection in CSF.