Diphtheritic polyneuropathy: a clinical study and comparison with Guillain-Barré syndrome

Article Topic: Neuropathies Due to Infections and Antimicrobial Treatments

Purpose of eview

The aim of this review is to discuss the presentation, diagnosis, and management of polyneuropathy (PN) in selected infections. Overall, most infection related PNs are an indirect consequence of immune activation rather than a direct result of peripheral nerve infection,  Schwann cell infection, or toxin production, though note this review will describe infections that cause PN through all these mechanisms. Rather than dividing them by each infectious agent separately, we have grouped the infectious neuropathies according to their presenting phenotype, to serve as a guide to clinicians. Finally, toxic neuropathies related to antimicrobials are briefly summarized.

Recent findings

While PN from many infections is decreasing, increasing evidence links infections to variants of GBS. Incidence of neuropathies secondary to use of HIV therapy has decreased over the last few years.

Summary

In this manuscript, a general overview of the more common infectious causes of PN will be discussed, dividing them across clinical phenotypes: large- and small-fiber polyneuropathy, Guillain-Barré syndrome (GBS), mononeuritis multiplex, and autonomic neuropathy. Rare but important infectious causes are also discussed.

Spectrum of Neurological Outcomes in Diphtheria: A Case Series

Diphtheria is an acute infectious disease caused by the exotoxin produced by Corynebacterium diphtheriae, a gram positive bacteria. It has propensity to affect mainly cardiac muscle and nervous system. To study the percentage, spectrum of patients with various neurological complications and the pattern of recovery in followed up confirmed cases of diphtheria. Single centre prospective analysis of neurological complications in diphtheria patients from June 2019 to September 2020 at SMS Medical College and hospital,Jaipur. In this study, 60 cases were included. Immunised cases were 60% (36 out of 60 cases) whereas unimmunised constituted the rest 40% (24 out of 60 cases). Neurological complications were observed in 15% of the cases (9 out of 60). Isolated palatal palsy was the most common complication (4 out of 9 cases, 44.44%), succeeded by lower limb LMN palsies (2 out of 9 cases, 22.22%) with unilateral facial nerve palsy, bilateral abductor palsy and paralytic ileus constituting the rest (1 out of 9 cases each, 11.11% each). Onset of complications ranged from 10 to 36 days whereas recovery was complete and without any residual sequelae between 60 to 240 days. Our study concluded that neurological complications form a sizeable portion of post diptheritic complications and carries good prognosis, hence timely diagnosis and differentiation from other neuropathies is a pre requisite for rational management and contact tracing.

Clinical Profile and Outcome in Children with Post Diphtheritic Paralysis in a Tertiary Care Hospital in Southern India

OBJECTIVES

Post-Diphtheritic Paralysis (PDP), one of the most severe complications of diphtheria, is caused by exotoxin of Corynebacterium diphtheria. This study was planned since there has been a resurgence of diphtheria in India in recent years due to a number of epidemiological factors.

MATERIALS & METHODS

Thirty-five children with PDP were studied in a tertiary care hospital in Southern India.

RESULT

Neurological complications occurred in 38.5% of 91 patients with faucial diphtheria. Of the patients, 13 (37.1%) were unimmunized, 12 (34.3%) were partially immunized, two (5.7%) were completely immunized, and eight (22.6%) had unknown status. Isolated bulbar palsy and bulbar palsy followed by limb weakness were seen in 20 (57.1%) and 15 (42.9%) of the patients, respectively. The first symptoms of PDP occurred 5-34 days after the onset of local diphtheria infection. Eleven (31.4%) out of the 35 patients had received antitoxin between days 5-7 of illness. Ventilation-dependent respiratory failure occurred in three (8.6%) patients with PDP. Nine (25.7%) patients had evidence of co-existent myocarditis, while myocarditis with renal failure was seen in two (5.7%) patients. Four (11.4%) patients died, three from severe cardiomyopathy and one from aspiration. Demyelinating neuropathy was noted in 64% of the patients. Children with bulbar palsy recovered in 4-7 weeks, while limb symptoms improved in 6-17 weeks.

CONCLUSION

PDP should be considered in any child presenting with bulbar palsy/quadriparesis following previous history of fever/sore throat. Awareness and availability with timely administration of ADS within 48 hours are essential to reduce PDP, as antitoxin seems ineffective if administered after the second day of diphtheritic symptoms.

Epidemiological, clinical, and public health response characteristics of a large outbreak of diphtheria among the Rohingya population in Cox's Bazar, Bangladesh, 2017 to 2019: A retrospective study

BACKGROUND

Unrest in Myanmar in August 2017 resulted in the movement of over 700,000 Rohingya refugees to overcrowded camps in Cox's Bazar, Bangladesh. A large outbreak of diphtheria subsequently began in this population.

METHODS AND FINDINGS

Data were collected during mass vaccination campaigns (MVCs), contact tracing activities, and from 9 Diphtheria Treatment Centers (DTCs) operated by national and international organizations. These data were used to describe the epidemiological and clinical features and the control measures to prevent transmission, during the first 2 years of the outbreak. Between November 10, 2017 and November 9, 2019, 7,064 cases were reported: 285 (4.0%) laboratory-confirmed, 3,610 (51.1%) probable, and 3,169 (44.9%) suspected cases. The crude attack rate was 51.5 cases per 10,000 person-years, and epidemic doubling time was 4.4 days (95% confidence interval [CI] 4.2-4.7) during the exponential growth phase. The median age was 10 years (range 0-85), and 3,126 (44.3%) were male. The typical symptoms were sore throat (93.5%), fever (86.0%), pseudomembrane (34.7%), and gross cervical lymphadenopathy (GCL; 30.6%). Diphtheria antitoxin (DAT) was administered to 1,062 (89.0%) out of 1,193 eligible patients, with adverse reactions following among 229 (21.6%). There were 45 deaths (case fatality ratio [CFR] 0.6%). Household contacts for 5,702 (80.7%) of 7,064 cases were successfully traced. A total of 41,452 contacts were identified, of whom 40,364 (97.4%) consented to begin chemoprophylaxis; adherence was 55.0% (N = 22,218) at 3-day follow-up. Unvaccinated household contacts were vaccinated with 3 doses (with 4-week interval), while a booster dose was administered if the primary vaccination schedule had been completed. The proportion of contacts vaccinated was 64.7% overall. Three MVC rounds were conducted, with administrative coverage varying between 88.5% and 110.4%. Pentavalent vaccine was administered to those aged 6 weeks to 6 years, while tetanus and diphtheria (Td) vaccine was administered to those aged 7 years and older. Lack of adequate diagnostic capacity to confirm cases was the main limitation, with a majority of cases unconfirmed and the proportion of true diphtheria cases unknown.

CONCLUSIONS

To our knowledge, this is the largest reported diphtheria outbreak in refugee settings. We observed that high population density, poor living conditions, and fast growth rate were associated with explosive expansion of the outbreak during the initial exponential growth phase. Three rounds of mass vaccinations targeting those aged 6 weeks to 14 years were associated with only modestly reduced transmission, and additional public health measures were necessary to end the outbreak. This outbreak has a long-lasting tail, with Rt oscillating at around 1 for an extended period. An adequate global DAT stockpile needs to be maintained. All populations must have access to health services and routine vaccination, and this access must be maintained during humanitarian crises.

Toxin-associated infectious diseases: tetanus, botulism and diphtheria

PURPOSE OF REVIEW

The incidence rates of the toxin-related infectious diseases, tetanus, diphtheria and botulism declined dramatically over the past decades mainly because of the implementation of immunization programs also in low-and-middle-income countries (LAMICs) and by improving hygiene conditions. But still, single cases occur, and they need fastest possible recognition and management.

RECENT FINDINGS

Over the past 20 years, the incidence of neonatal tetanus has declined by more than 90%. This success was achieved by immunizing women in reproductive age in areas of high risk as sub-Saharan Africa and parts of Asia. Larger regional outbreaks of diphtheria have been reported from the former Soviet Union in the 1990s and from India in 2017. Botulism is still rare, mainly seen in infants and, in recent years, in intravenous drug abusers.

SUMMARY

Tetanus, diphtheria and botulism are rarities in high-income countries (HICs) with unlimited access to immunization programs and standard hygiene procedures. The diagnosis of all three diseases is still, even in the 21st century, based upon patient's history and clinical signs and symptoms. Neither biochemical bedside tests nor neuroradiological investigations help to confirm the diagnosis in an emergency situation.

Diphtheria

Diphtheria is a potentially fatal infection mostly caused by toxigenic Corynebacterium diphtheriae strains and occasionally by toxigenic C. ulcerans and C. pseudotuberculosis strains. Diphtheria is generally an acute respiratory infection, characterized by the formation of a pseudomembrane in the throat, but cutaneous infections are possible. Systemic effects, such as myocarditis and neuropathy, which are associated with increased fatality risk, are due to diphtheria toxin, an exotoxin produced by the pathogen that inhibits protein synthesis and causes cell death. Clinical diagnosis is confirmed by the isolation and identification of the causative Corynebacterium spp., usually by bacterial culture followed by enzymatic and toxin detection tests. Diphtheria can be treated with the timely administration of diphtheria antitoxin and antimicrobial therapy. Although effective vaccines are available, this disease has the potential to re-emerge in countries where the recommended vaccination programmes are not sustained, and increasing proportions of adults are becoming susceptible to diphtheria. Thousands of diphtheria cases are still reported annually from several countries in Asia and Africa, along with many outbreaks. Changes in the epidemiology of diphtheria have been reported worldwide. The prevalence of toxigenic Corynebacterium spp. highlights the need for proper clinical and epidemiological investigations to quickly identify and treat affected individuals, along with public health measures to prevent and contain the spread of this disease.

Clinical electrophysiology of axonal polyneuropathies

Axonal neuropathies encompass a wide range of acquired and inherited disorders with electrophysiologic characteristics that arise from the unique neurophysiology of the axon. Accurate interpretation of nerve conduction studies and electromyography requires an in-depth understanding of the pathophysiology of the axon. Here we review the unique neurophysiologic properties of the axon and how they relate to clinical electrodiagnostic features. We review the length-dependent Wallerian or "dying-back" processes as well as the emerging body of literature from acquired axonal neuropathies that highlights the importance of axonal disease at the nodes of Ranvier. Neurophysiologic features of individual inherited and acquired axonal diseases, including primary nerve disease as well as systemic immune mediated, metabolic, and toxic diseases involving the peripheral nerve, are reviewed. This comprehensive review of electrodiagnostic findings coupled with the current understanding of pathophysiology will aid the clinician in the evaluation of axonal polyneuropathies.

Severe diphtheria with neurologic and myocardial involvement in a Swedish patient: a case report

Background

Diphtheria is caused by Corynebacterium diphtheriae. Although waning in incidence diphtheria can cause severe disease as in this rare Swedish case with several complications.

Case presentation

A 55-year old male presented to the emergency room with severe respiratory symptoms and greyish membranes in the airways, which turned positive for C. diphtheriae. He was put on ventilator support and remained hospitalized for three months. During care he developed myocarditis and severe neurological disease and he was also co-infected with tuberculosis. The patient was discharged with a favorable outcome.

Conclusions

Diphtheria should be suspected in patients with life-threatening pneumonia especially if the patient has a history of travelling. Our patient was not treated with diphtheria anti-toxin (DAT) which may have contributed to the severity of the disease.

Prospective Study of Diphtheria for Neurological Complications

Aim

To study the spectrum of neurological complications of diphtheria, timing of onset with respect to respiratory disease, and pattern of recovery.

Settings and Design

Prospective, observational, hospital-based study conducted in tertiary care hospital.

Materials and Methods

Twenty-eight cases of diphtheria with neurological complications were admitted during the period of study. Demographic profile, age, gender, status of immunization, past history stressing on the severity of the respiratory disease, and complaints regarding diverse complications of diphtheria were recorded. Detailed clinical and central nervous system examinations along with relevant investigations were carried out.

Results

Children were in the age group of 3-18 years. All 28 children presented with bulbar symptoms. Isolated palatal palsy was present in 18 children (64%). Third cranial involvement was present in four children. Three children had unilateral lower motor neuron facial palsy and one child had sixth cranial nerve palsy. Nine children developed symmetric limb weakness. Diaphragmatic palsy was present in three children with the onset from 1-3 weeks after pharyngeal diphtheria. Loss of vasomotor tone was present in two children. Recovery was complete in all 28 children.

Conclusion

Pediatricians/neurophysicians should have a high index of suspicion to recognize diphtheritic polyneuropathy. It carries good prognosis, hence timely diagnosis and differentiation from other neuropathies is a prerequisite for rational management and contact tracing.

Infectious diseases causing autonomic dysfunction

OBJECTIVES

To review infectious diseases that may cause autonomic dysfunction.

METHODS

Review of published papers indexed in medline/embase.

RESULTS

Autonomic dysfunction has been reported in retrovirus (human immunodeficiency virus (HIV), human T-lymphotropic virus), herpes viruses, flavivirus, enterovirus 71 and lyssavirus infections. Autonomic dysfunction is relatively common in HIV-infected patients and heart rate variability is reduced even in early stages of infection. Orthostatic hypotension, urinary dysfunction and hypohidrosis have been described in tropical spastic paraparesis patients. Varicella zoster reactivation from autonomic ganglia may be involved in visceral disease and chronic intestinal pseudo-obstruction. Autonomic and peripheral nervous system dysfunction may happen in acute tick-borne encephalitis virus infections. Hydrophobia, hypersalivation, dyspnea, photophobia, and piloerection are frequently observed in human rabies. Autonomic dysfunction and vagal denervation is common in Chagas disease. Neuronal depopulation occurs mainly in chagasic heart disease and myenteric plexus, and megacolon, megaesophagus and cardiomyopathy are common complications in the chronic stage of Chagas disease. Parasympathetic autonomic dysfunction precedes left ventricle systolic dysfunction in Chagas disease. A high prevalence of subclinical autonomic neuropathy in leprosy patients has been reported, and autonomic nerve dysfunction may be an early manifestation of the disease. Autonomic dysfunction features in leprosy include anhidrosis, impaired sweating function, localised alopecia ,and reduced heart rate variability. Urinary retention and intestinal pseudo-obstruction have been described in Lyme disease. Diphtheritic polyneuropathy, tetanus and botulism are examples of bacterial infections releasing toxins that affect the autonomic nervous system.

CONCLUSIONS

Autonomic dysfunction may be responsible for additional morbidity in some infectious diseases.

Potency of a human monoclonal antibody to diphtheria toxin relative to equine diphtheria anti-toxin in a guinea pig intoxication model

Prompt administration of anti-toxin reduces mortality following Corynebacterium diphtheriae infection. Current treatment relies upon equine diphtheria anti-toxin (DAT), with a 10% risk of serum sickness and rarely anaphylaxis. The global DAT supply is extremely limited; most manufacturers have ceased production. S315 is a neutralizing human IgG1 monoclonal antibody to diphtheria toxin that may provide a safe and effective alternative to equine DAT and address critical supply issues. To guide dose selection for IND-enabling pharmacology and toxicology studies, we dose-ranged S315 and DAT in a guinea pig model of diphtheria intoxication based on the NIH Minimum Requirements potency assay. Animals received a single injection of antibody premixed with toxin, were monitored for 30 days, and assigned a numeric score for clinical signs of disease. Animals receiving ≥ 27.5 µg of S315 or ≥ 1.75 IU of DAT survived whereas animals receiving ≤ 22.5 µg of S315 or ≤ 1.25 IU of DAT died, yielding a potency estimate of 17 µg S315/IU DAT (95% CI 16–21) for an endpoint of survival. Because some surviving animals exhibited transient limb weakness, likely a systemic sign of toxicity, DAT and S315 doses required to prevent hind limb paralysis were also determined, yielding a relative potency of 48 µg/IU (95% CI 38–59) for this alternate endpoint. To support advancement of S315 into clinical trials, potency estimates will be used to evaluate the efficacy of S315 versus DAT in an animal model with antibody administration after toxin exposure, more closely modeling anti-toxin therapy in humans.

Diphtheritic polyneuropathy in the wake of resurgence of diphtheria

OBJECTIVE

To study the clinical profile and outcome in children with diphtheritic polyneuropathy (DP).

METHODOLOGY

13 children with polyneuropathy were included in this study. Their demographic profile, age, sex and immunization status were recorded. Detailed clinical and neurological examination was done. Investigations like CSF analysis, NCV studies, MRI brain were done. The results were tabulated and analyzed.

RESULTS

All the children presented with bulbar palsy and had h/o membranous tonsillitis. Isolated palatal palsy was seen in 7 children (53%). 6 (46.1%) children developed quadriparesis. 1 child expired and recovery is complete in rest of the 12 children. Children with isolated bulbar palsy recovered within 2 to 4 weeks while children with quadriparesis recovered within 5-6 wks.

CONCLUSIONS

Any child diagnosed with diphtheria should be followed for 3-6 months in anticipation of neurological complications. DP carries good prognosis hence timely diagnosis and differentiation from other neuropathies is a prerequisite for rational management.

Corynebacterium ulcerans cutaneous diphtheria

We describe the case of a patient with cutaneous diphtheria caused by toxigenic Corynebacterium ulcerans who developed a right hand flexor sheath infection and symptoms of sepsis such as fever, tachycardia, and elevated C-reactive protein, after contact with domestic cats and dogs, and a fox. We summarise the epidemiology, clinical presentation, microbiology, diagnosis, therapy, and public health aspects of this disease, with emphasis on improving recognition. In many European countries, C ulcerans has become the organism commonly associated with cutaneous diphtheria, usually seen as an imported tropical disease or resulting from contact with domestic and agricultural animals. Diagnosis relies on bacterial culture and confirmation of toxin production, with management requiring appropriate antimicrobial therapy and prompt administration of antitoxin, if necessary. Early diagnosis is essential for implementation of control measures and clear guidelines are needed to assist clinicians in managing clinical diphtheria. This case was a catalyst to the redrafting of the 2014 national UK interim guidelines for the public health management of diphtheria, released as final guidelines in March, 2015.

Access to diphtheria antitoxin for therapy and diagnostics

The most effective treatment for diphtheria is swift administration of diphtheria antitoxin (DAT) with conjunct antibiotic therapy. DAT is an equine immunoglobulin preparation and listed among the World Health Organization Essential Medicines. Essential Medicines should be available in functioning health systems at all times in adequate amounts, in appropriate dosage forms, with assured quality, and at prices individuals and the community can afford. However, DAT is in scarce supply and frequently unavailable to patients because of discontinued production in several countries, low economic viability, and high regulatory requirements for the safe manufacture of blood-derived products. DAT is also a cornerstone of diphtheria diagnostics but several diagnostic reference laboratories across the European Union (EU) and elsewhere routinely face problems in sourcing DAT for toxigenicity testing. Overall, global access to DAT for both therapeutic and diagnostic applications seems inadequate. Therefore--besides efforts to improve the current supply of DAT--accelerated research and development of alternatives including monoclonal antibodies for therapy and molecular-based methods for diagnostics are required. Given the rarity of the disease, it would be useful to organise a small stockpile centrally for all EU countries and to maintain an inventory of DAT availability within and between countries.

Neurologic manifestations of diphtheria and pertussis

Historically, diphtheria was a major cause of morbidity and mortality in the prevaccine era. However, in recent times there has been a resurgence of diphtheria, especially in the newly independent states of the former USSR. Diphtheritic polyneuropathy can be a serious complication in patients who have a severe infection. In patients with pertussis, seizures and encephalopathy can occur as a complication of asphyxia. Vaccination against diphtheria and pertussis in children and booster vaccination in adults is recommended. DTP (diphtheria, tetanus, pertussis) vaccination has been shown to increase the risk of febrile seizures in children. Currently, it appears that the risk of vaccine-induced encephalopathy and/or epilepsy following DTP vaccination, if any, is extremely low.

Detection of diphtheritic polyneuropathy by acute flaccid paralysis surveillance, India

Diphtheritic polyneuropathy is a vaccine-preventable illness caused by exotoxin-producing strains of Corynebacterium diphtheriae. We present a retrospective convenience case series of 15 children (6 girls) <15 years of age (mean age 5.2 years, case-fatality rate 53%, and 1 additional case-patient who was ventilator dependent at the time of last follow-up; median follow-up period 60 days) with signs and symptoms suggestive of diphtheritic polyneuropathy. All cases were identified through national acute flaccid paralysis surveillance, which was designed to detect poliomyelitis in India during 2002–2008. We also report data on detection of diphtheritic polyneuropathy compared with other causes of acute flaccid paralysis identified by this surveillance system.

Post-diphtheritic neuropathy: a clinical study in paediatric intensive care unit of a developing country

Summary

A retrospective study was done on 48 consecutive patients with clinical diagnosis of postdiphtheritic neuropathy admitted to the paediatric intensive care unit of tertiary care hospital in North India between January 2008 and December 2010 to study the clinical profile of post-diphtheritic neuropathy in children. The case records were reviewed and information regarding personal details, clinical features, recovery parameters and outcome was recorded using a predesigned proforma. Median age was 4.25 years. All cases were unimmunized. Median latency period was 15 days. Of the children, 52% had palatal palsy whereas 48% had limb weakness initially. Median duration of progression of weakness was five days. Limb muscle weakness was present in 94%. Respiratory muscles were involved in 85.4% cases and 60.4% required mechanical ventilation, while 14.6% had fatal outcome and 10.4% had hypoxic neurological injury. Boys were affected more. Median duration of latency was shorter; muscle weakness, progression and recovery were faster as compared with observational studies in adults.

Acute and chronic polyradiculopathies

Polyradiculopathies are uncommon peripheral nervous system syndromes that result from a variety of conditions. The clinical manifestations are variable but often include symmetric or asymmetric distal and proximal weakness with a variable degree of sensory loss and reduction or loss of reflexes. The most common cause of an acute polyradiculopathy is acute inflammatory demyelinating polyradiculopathy (also known as Guillain-Barré syndrome); however, other inflammatory, infectious, or neoplastic causes can present with similar features. Chronic polyradiculopathies include chronic inflammatory demyelinating polyradiculopathy as well as paraprotein-related syndromes and other inflammatory and infectious causes. Evaluation using a combination of serologic studies, electrodiagnostic testing, and CSF evaluation can help to identify the underlying etiology and implement the appropriate treatment. This article reviews the approach to patients with suspected polyradiculopathy and the features of the more common causes of acute and chronic polyradiculopathies.

Infectious neuropathies

PURPOSE OF REVIEW

The purpose of this review is to address bacterial, viral, and other infectious causes of neuropathy or neuronopathy, with an emphasis on clinical manifestations and treatment.

RECENT FINDINGS

Most infectious neuropathies have been well described for some time and treatments are well established. An exception is HIV-associated distal symmetric polyneuropathy, which is an area of active research. Current work in this area focuses on epidemiology, risk factors, and underlying mechanisms.

SUMMARY

Infectious diseases are an important part of the differential diagnosis of peripheral nerve disorders because they are among the most amenable to treatment. However, diagnosis of infectious peripheral neuropathy may be challenging because of variability in a number of factors, including the pattern of deficits, geographic distribution of pathogens, length of time from the onset of infection to the development of neuropathy, and mechanism of nerve injury.

Diphtheria in the United Kingdom, 1986-2008: the increasing role of Corynebacterium ulcerans

Diphtheria is an uncommon disease in the UK due to an effective immunization programme; consequently when cases do arise, there can be delays in diagnosis and case-fatality rates remain high. We reviewed 102 patients with infections caused by toxigenic corynebacteria (an average of four per year) reported in the UK between 1986 and 2008: 42 Corynebacterium diphtheriae, 59 C. ulcerans and one C. pseudotuberculosis, as well as 23 asymptomatic carriers. Five fatalities were reported, all in unvaccinated patients. The major risk factor for C. diphtheriae infection continued to be travel to an endemic country. C. ulcerans infections became more common than C. diphtheriae infections in the UK; they were associated with contact with companion animals. The occurrence of indigenous severe C. ulcerans infections and imported C. diphtheriae cases highlights the need to maintain UK routine vaccination coverage at the 95% level in the UK, as recommended by the World Health Organization.

A review of the international issues surrounding the availability and demand for diphtheria antitoxin for therapeutic use

Diphtheria treatment requires early administration of diphtheria antitoxin (DAT), an immunoglobulin preparation that neutralises circulating diphtheria toxin. Here, we review issues relating to the supply and use of DAT and assess its availability by means of an international survey. Results showed that several countries do not currently hold DAT stockpiles due to low prevalence, and hence perceived risk of diphtheria, and/or difficulties in obtaining DAT supplies. The potential for importation of cases into any country exists globally, since diphtheria remains endemic in many regions. It is therefore important that DAT be readily available - particularly since waning diphtheria immunity has been observed among adult populations in countries with good vaccination coverage. Options for diphtheria therapy are discussed.

Neurologists and the threat of bioterrorism

Neurologists are most likely to become involved in primarily diagnosing those bioterrorist attacks utilising botulinum toxin. Oral ingestion, or possibly inhalation, are likely routes of delivery. The characteristic descending paralysis starts in the extraocular and bulbar muscles, with associated autonomic features. Repetitive nerve stimulation usually shows an incremental muscle response. Treatment is supportive. The differential diagnosis is from naturally occurring paralysing illnesses such as Guillain-Barré syndrome, myasthenic crisis or diphtheria, from paralysing seafood neurotoxins (tetrodotoxin, saxitoxin), snake envenomation, and from chemical warfare poisoning by organophosphates. Primary neurological infections are less feasible for use as bioweapons. There are theoretical possibilities of Venezuelan equine encephalitis transmission by inhalation and secondary zoonotic transmission cycles sustained by horses and mosquitoes. Severe haemorrhagic meningitis regularly occurs in anthrax, usually in the aftermath of severe systemic disease likely to have been transmitted by spore inhalation. Panic and psychologically determined 'me-too' symptomatology are likely to pose the biggest diagnostic and management burden on neurologists handling bioterrorist attack on an institution or a random civilian population. Indeed civilian panic and disablement of institutional operations are likely to be prominent intentions of any bioterrorist attack.

Antidiphtheria antibody responses in patients and carriers of Corynebacterium diphtheriae in the Arkhangelsk region of Russia

Diphtheria is under control in industrialized countries. However, single cases and outbreaks still occur and the disease is not completely understood. Forty-three individuals suspected of having diphtheria who were referred to the Infectious Disease Hospital of Arkhangelsk from December 1994 to March 1995 were included in this study. Fifteen patients were diagnosed as having diphtheria and received equine hyperimmune antidiphtheria toxin antiserum, and 28 were diagnosed as carriers, 12 with nondiphtherial tonsillitis or pharyngitis and 16 without symptoms. Serum samples were obtained on admission and during the course of the disease or during follow-up of carrier status. Samples were analyzed for antibodies against diphtheria toxin with both an in vitro neutralization test (NT) and a human-specific enzyme immunoassay. All of the cases but one were confirmed by a positive culture. Twelve patients had pharyngeal diphtheria, and three had combined laryngeal and pharyngeal disease. Half of the patients had life-threatening disease, and one died. On admission, the median antibody titers measured with the NT were 0.085 IU/ml for the patients, 5.12 IU/ml for the symptomatic carriers, and 10.24 IU/ml for the healthy carriers. All of the diphtheria patients but one and nine of the carriers (six symptomatic and three healthy) had increased antibody levels during the first 7 to 10 days after admission. No obvious correlation was revealed between the antibody level or its kinetics and the course of the disease. Antibody levels on admission of >1 IU/ml were associated with a low risk of diphtheria.

Diphtheria with polyneuropathy in a closed community despite receiving recent booster vaccination

INTRODUCTION AND METHODS

We report 20 patients aged 18-24 years from Latvia with diphtheritic polyneuropathy. All lived in a closed community and 80% were known to have been fully vaccinated against diphtheria until at least 14 years old. Diphtheria antitoxin had been administered within 3 days of the onset of upper respiratory tract infection in 16 patients and 15 received antibiotics.

RESULTS

Neurological symptoms developed after a median of 43 days (range 35-58) compared to only 10 days in previous studies of unvaccinated patients. All showed evidence of mild limb polyneuropathy with electrophysiological evidence of polyneuropathy. Only 30% showed early bulbar abnormalities compared to the usual rate of over 95% in diphtheritic polyneuropathy. However, 45% had later bulbar deterioration coinciding with the limb polyneuropathy.

CONCLUSIONS

These patients show that an attenuated form of polyneuropathy of later onset, with less prominent early bulbar features, can occur in patients vaccinated against diphtheria according to schedule but living in a closed community in a country where diphtheria remains endemic.

Clinical features and pathophysiological basis of sensory neuronopathies (ganglionopathies)

Sensory ganglionopathies have a frequent association with neoplastic disorders (paraneoplastic subacute sensory neuronopathy, or SSN) or dysimmune disorders (Sjögren's syndrome, SS; Miller Fisher syndrome; and Bickerstaff's brainstem encephalitis, BBE), with drugs, such as cisplatin or pyridoxine, and with inherited disorders with degeneration of dorsal root ganglion cells. Unsteady gait and pseudoathetoid movements of the hand are the distinctive signs encountered in these disorders. The chronic disorders are characterized by non-length-dependent abnormalities of sensory nerve action potentials (SNAPs) and differ from other sensory neuropathies in showing a global, rather than distal, decrease in SNAP amplitudes. This review focuses on recent advances in defining the mechanisms involved in sensory ganglionopathies. Specific topics include a summary of their clinical features, pathological findings, and immunopathology. In SSN, early diagnosis by the detection of anti-Hu antibodies and early treatment of the cancer gives the best chance of stabilizing the disorder. In SS sensory ganglionitis, response to treatment has been disappointing, but immunomodulating treatments are emerging. The immunological profile common to BBE and Fisher syndrome supports a common pathogenesis. In toxic sensory neuronopathy, no treatment is available. The differential diagnosis involves separating sensory ganglionopathies from other ataxic polyneuropathies, such as infectious neuropathies, sensory neuropathies with various autoantibodies, and the neuropathies seen in celiac disease.