Toxic polyneuropathy due to glue-sniffing. Report of two cases with a light and electron-microscopic study of the peripheral nerves and muscles

The Role of Protein Adduction in Toxic Neuropathies of Exogenous and Endogenous Origin

The peripheral (axonal) neuropathy associated with repeated exposure to aliphatic and aromatic solvents that form protein-reactive γ-diketones shares some clinical and neuropathological features with certain metabolic neuropathies, including type-II diabetic neuropathy and uremic neuropathy, and with the largely sub-clinical nerve damage associated with old age. These conditions may be linked by metabolites that adduct and cross-link neuroproteins required for the maintenance of axonal transport and nerve fiber integrity in the peripheral and central nervous system.

Clinical, socio-demographic, neurophysiological and neuropsychiatric evaluation of children with volatile substance addiction

BACKGROUND

Abuse of organic volatile substances in children has become a social health problem that is increasing in the recent years. Among these substances, toluene is highly preferred by abusers because of its euphoric effect, cheapness and easy availability. There is no published research on the clinical and neurophysiological evaluation of children with short-term volatile substance addiction.

METHODS

In this study, socio-demographic characteristics were questioned in 12 children with a mean age of 15 years and a duration of toluene abuse for a mean of 2.3 years, and the clinical characteristics of central and peripheral nervous system damage caused by volatile substances, particularly by toluene were analysed, and probable neurological disorders were investigated by means of neurophysiological and neuropsychological tests. All tests were compared with a control group.

RESULTS

Fifty-eight percent of the children included in the study had pathological findings in the neurological examination. There was pyramidal involvement in 25% and peripheral nerve involvement in 33.3% of the cases. Evaluation of the cognitive functions revealed 33.3% pathology in the 'Short Test of Mental Status' which assesses functions of orientation, attention, learning, arithmetic calculation, abstraction, information, construction and recall. Sensorial polyneuropathy was found in 33.3% of the cases in nerve conduction studies. Somatosensory-evoked potentials revealed pathology in 16.7% of the cases and brainstem-evoked potentials in 50% of the cases. No pathology was observed in electroencephalography and visual-evoked potentials.

CONCLUSION

In our study, neurophysiological and neuropsychiatric tests revealed that toluene causes slow progressive, clinical and subclinical central and peripheral nerve damage. In Turkey, because of cheapness, easy availability and legal use of volatile substances, the clinical extent of systemic and neurological toxicity of volatile substance abuse is increasing. Abuse of volatile substances, a currently increasing social issue, may create important physical problems which can be permanent.

n-Hexane neuropathy caused by addictive inhalation: clinical and electrophysiological features

To assess the clinical and electrophysiological features of n-hexane neuropathy caused by addictive inhalation, 4 patients were studied in the progressive phase. The neurological manifestations were characterized by subacute predominantly motor polyneuropathy and disease progression despite discontinuance of the chemicals, which were similar to those reported in industrial exposure, although with a severer degree associated with anorexia and body weight loss. Electrophysiological studies showed that all showed multifocal conduction block and profound conduction slowing, as well as features of axonal degeneration. Sural nerve biopsy showed axonal loss, axonal swelling, and thin myelin probably due to retraction by axonal swelling. n-Hexane abuse causes severe subacute polyneuropathy. The mixed axonal and demyelinating electrophysiological features were consistent with peculiar pathological findings. Conduction block, probably due to paranodal myelin retraction or ongoing wallerian degeneration, is very frequent and could be responsible for the clinical deficits, especially in the early phase of illness.

The pathogenesis of neurodegenerative disease: neurotoxic mechanisms of action and genetics

The role of environmental and occupational exposures to neurotoxicants in the pathogenesis of neurodegenerative disease has not been fully elucidated. Recent published research on whether genetic polymorphisms contribute to individual susceptibility to develop neurodegenerative diseases such as Parkinson's disease have been equivocal at best. This review relates putative mechanisms of neurotoxicant-induced cell damage to polymorphisms in the genes that encode for the enzymes involved in the metabolism of neurotoxicants. The effects that genetically induced alterations in enzyme functioning have on neurotoxicant metabolism and how this relates to the risk of neurotoxic effects among exposed individuals are reviewed. A pragmatic approach to future research in the area of neurodegenerative disease is developed on the basis of the interrelationship between known routes of neurotoxicant metabolism and human genetics.

Focal conduction block in n-hexane polyneuropathy

A 19-year-old man with an asymptomatic history of recreational gasoline vapor inhalation presented with subacute progressive quadriparesis. For 2 weeks, he had intensely inhaled Coleman fuel oil vapor, which contains n-hexane. Nerve conduction studies including near-nerve needle stimulation showed focal conduction block in the bilateral median and ulnar nerves. Sural nerve biopsy was consistent with giant axonal neuropathy. Conduction block as seen in this case has not heretofore been described in n-hexane polyneuropathy.

n-Hexane neuropathy due to rubber cement sniffing

n-Hexane neuropathy has been described after glue sniffing and industrial exposure. Onset may be subacute and reminiscent of Guillain-Barré syndrome. Although the primary pathology is axonal, electrophysiologic evaluation is frequently most remarkable for conduction slowing. We describe a patient with a severe subacute neuropathy following n-hexane exposure via glue sniffing. Although symptoms worsened after termination of exposure ("coasting"), strength gradually improved to near normal. Sources of toxic exposure should be sought in all patients with subacute demyelinating neuropathies.

Peripheral and central conduction in n-hexane polyneuropathy

Electrophysiological findings of 27 males with industrial n-hexane polyneuropathy (HPNP) are presented. The results of needle electromyography and nerve conduction studies were compatible with primarily axonal polyneuropathy with secondary segmental demyelination. Motor conduction velocities were the slowest in distal regions of the nerves. In the proximal nerve segments, which were partly tested by magnetic stimulation of the nerve roots, this slowing was much less pronounced. The reduction in mean motor conduction velocities in the forearm segments of ulnar nerves was more than 30% in comparison to the control group means. This reduction was only 10% in the neck-axilla segments. We think that this finding is a reflection of the distal axonopathy process. Central motor conduction times calculated by transcranial magnetic stimulation and spinal nerve root stimulation were found to be prolonged in HPNP patients, indicating that descending motor pathways are affected in human HPNP.

Axonal swellings in human intramuscular nerves

The presence, morphology, distribution, and abundance of axonal swellings in intramuscular nerves were evaluated. Axonal swellings were present in intramuscular nerves in 42% of 127 muscle biopsies from patients with a variety of conditions. The incidence was highest in muscle from patients with peripheral neuropathy, but swellings were present in muscle from patients with motor neuron disease, primary muscle diseases, and some individuals without clinical or histological evidence of neuromuscular disease. The greatest number of swellings in intramuscular nerves was in muscle from patients with chronic inflammatory demyelinating neuropathy. Swellings were spherical or elliptical, 4-20 microns in diameter, 5-30 microns in length, and composed of neurofilaments. Swellings were present only in myelinated axons of intramuscular nerves, proximal to nodes of Ranvier or in internodal regions. Swellings were not associated with axonal degeneration. They were probably not transported. The formation or accumulation of swellings may reflect altered axonal dynamics common to a number of disease processes.

Relation of distribution of conduction velocities to nerve biopsy findings in n-hexane poisoning

Distribution of conduction velocities (DCV) of sensory fibers in sural nerve was investigated in three patients with n-hexane poisoning. Measurements were made at 1-2 months, 4-9 months, and at 11, 23, and 36 months after ending exposure. A sural nerve biopsy was obtained from one of the patients. The results indicated the characteristic changes of n-hexane toxicity: myelinated nerve fiber degeneration and paranodal swelling, resulting in changes in the fiber diameter distribution. The DCV documented these changes. After removal from toxic exposure, varying degrees of recovery were studied clinically and evaluated with nerve conduction parameters. The DCV reflects the pathological changes in nerve in toxic neuropathy due to n-hexane.

Biphasic recovery in n-hexane polyneuropathy. A clinical and electrophysiological study

We studied the course of recovery in n-hexane polyneuropathy in 4 patients by quantitatively assessing clinical and electrophysiological features. The electrophysiological study included measures of motor conduction of the median, ulnar, tibial and peroneal nerves and sensory conduction of the median, ulnar and sural nerves. After cessation of exposure, there was an initial worsening in muscle strength, sensory deficit and nerve conduction for up to 2-5 months. This deterioration was more severe and prolonged in the lower limbs than in the upper limbs. The period of deterioration was followed by a slow recovery studied for 1 year.

Chronic neurological toxicity associated with exposure to volatile substances

1. The main neurological disorders associated with chronic VSA are peripheral neuropathy, cerebellar disease, chronic encephalopathy and dementia. Apart from peripheral neuropathy, the clinical features are non-specific, evidence for solvent-related toxicity is in most cases circumstantial and there is no clear dose/response relationship. 2. Peripheral neuropathy is mainly associated with n-hexane and methyl n-butyl ketone. 3. Cerebellar disease is usually associated with toluene exposure; in the more severe cases there is often radiological evidence of irreversible cerebellar atrophy. 4. Chronic encephalopathy and dementia are the most serious consequence of solvent exposure, particularly to toluene in abusers and to mixed solvents in industrial workers. Postmortem studies in some abusers have shown generalized axonal degeneration, demyelination and brain atrophy. 5. Further studies on low level solvent exposure are needed as little is known about the neurological consequences of mild VSA, especially as regards individual susceptibility and possible interactions between solvents and other toxins such as ethanol.

2,5-Hexanedione neuropathy is associated with the covalent crosslinking of neurofilament proteins

Protein composition in different segments along nerves from rats intoxicated with 2,5-hexanedione (HD) was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and by immunoblotting, using monoclonal antibodies specific for each of the three neurofilament polypeptide components (H, M, and L). Comparison with nerve protein extracts from normal (control) rats revealed a disappearance of the largest neurofilament polypeptide (H), accompanied by accumulation of higher-molecular-weight products that were immunoreactive with H-specific antibodies. Both the extent of this crosslinking and its localization in particular portions of peripheral nerves showed a correlation with HD dosage and with the known progression of ultrastructural features during HD-induced neuropathy. Similar changes were not detected for the M and L neurofilament components.

Volatile substance abuse: a review of possible long-term neurological, intellectual and psychiatric sequelae

The possibility that chronic abuse of volatile substances can cause permanent neurological, psychiatric, and intellectual sequelae is critically reviewed. Toluene, present in the commonly used adhesives, is most often implicated in 'glue sniffing'; this review focuses on its potential long-term effects. Many criticisms--particularly poor matching of control samples and inability to distinguish between acute and chronic effects--can be levelled at the available studies, while no adequate follow-up studies have been performed. In the light of present knowledge, the possibility that permanent structural brain damage, with accompanying psychiatric manifestations, results from solvent abuse remains inconclusive.

Effects of IDPN-induced axonal swellings on conduction in motor nerve fibers

Paranodal demyelination produces a reduction of conduction velocity and conduction block. The relative proportions of these changes appear to vary among different demyelinating disorders. In this study we have examined the effects on conduction of paranodal demyelination produced by giant axonal swellings. The axonal swellings were induced in rats by administration of beta, beta'-iminodipropionitrile (IDPN). In this experimental model synchronous axonal swellings occur in the proximal region of virtually every alpha-motorneuron without evidence of segmental demyelination or fiber loss. Conduction across the motor neuron was evaluated by two methods: a monosynaptic reflex pathway and intracellular recording from single motor neurons. Increases in the delay across the central region of the monosynaptic reflex pathway began between 2 and 4 days after toxin administration. Intracellular studies confirmed that the slowing occurred across the proximal regions of the motor axons; more distal regions of the motor axons were unaffected. The substantial reduction in conduction velocity over the swollen segment occurs with only moderate evidence of conduction block, as assayed by a reduction in the H-reflex/M-response amplitude ratio. Parallel morphological studies showed that in the enlarged fibers the myelin terminal loops maintained contact with the axon but were displaced from the paranodal region into the internode. The appearance of this "passive" paranodal demyelination correlated closely with the increase in conduction delay. We suggest that the contact maintained by the displaced myelin terminal loops with the axolemma allows saltatory conduction to continue, and explains the paucity of conduction block in this model despite the prominent conduction slowing.

Glue sniffing neuropathy

Three young men are described in whom a severe, subacute, predominantly motor peripheral neuropathy resulted from the deliberate inhalation of glue vapour. Weakness began after several years of daily glue sniffing and was marked in proximal as well as distal muscles. Muscle wasting was prominent at the time of presentation. Deterioration continued for several weeks after glue sniffing ceased. Peripheral nerve conduction was markedly slow and there was extensive denervation in the muscles. Characteristic changes were seen on sural nerve biopsy. The habit of glue sniffing is now widespread amongst Australian adolescents and this factor should be considered when any young person presents with a peripheral neuropathy.

Neurophysiological signs of brain damage due to glue sniffing

Recordings of the brain electrical responses to pattern reversal (checkerboard) visual stimuli showed significantly increased latencies in a group of 12 young people who had been sniffing glue over a prolonged period. Only small improvements were observed in two people who had repeat recordings after 6 months' abstinence. These results show that chronic glue sniffing can lead to long lasting brain damage.

Tolerance and reverse tolerance to toluene inhalation: effects on open-field behavior

Rats were exposed by inhalation to extremely high concentrations of toluene vapors twice daily for six weeks, as an animal model of organic solvent abuse. At preset intervals during repeated exposure, the rats were exposed to test concentrations of toluene and effects on behavior in an open field were measured. Concentration-effect curves were determined during Weeks 4 to 6 of repeated exposure. Tolerance to toluene was measured as a decreased response to the test exposure and a shift of the concentration-effect curve to the right. Reverse tolerance was measured as an increased response to the test exposure and a shift shift of the concentration-effect curve to the left. Results demonstrated that the effects of repeated exposure to toluene showed behavioral selectivity: tolerance developed to ataxia, hindlimb myoclonus, and inhibition of rearing, whereas reverse tolerance developed to headshakes and increased locomotor activity.

Toxic polyneuropathy of shoe workers in Italy. A clinical, neurophysiological and follow-up study

Cases of polyneuropathy due to exposure to industrial solvents have been studied at several shoe factories in the province of Siena. After the screening of 654 employees 98 verified cases were detected. Of these, 16 were rated as moderate to severe, 45 as mild, and 37 were minimally involved but with characteristic electrodiagnostic abnormalities. Follow-up study in 53 patients showed that neurological signs and symptoms as well as electrodiagnostic abnormalities continued for years in several patients. In addition, after a year's observation, some patients showed signs of central nervous system dysfunction such as spasticity of the lower limbs and increased deep tendon reflexes. High percentages of commercial n-hexane were found in all the samples of glues and solvents collected from home-workers and from factories where cases of polyneuropathy occurred.

Progressive optic neuropathy and sensorineural hearing loss due to chronic glue sniffing

A 27-year-old male developed cerebral and cerebellar atrophy over a period of five years of extensive glue sniffing. He also developed bilateral optic atrophy with blindness and severe sensorineural hearing loss. Investigation failed to show any other cause for the visual or hearing loss. Peripheral polyneuropathy and central nervous system damage may follow chronic toluene toxicity, but these auditory and visual complications have not previously been described.

Persistent visual hallucinations secondary to chronic solvent encephalopathy: case report and review of the literature

A case of solvent encephalopathy presenting with persistent visual hallucinations, and characterised by a diffusely abnormal EEG and delayed visually evoked responses to checkerboard pattern reversal (VERs), is described. Abnormalities in the EEG and VERs showed minimal improvement over many months of abstinence from glue sniffing. The literature on the neurological sequelae of solvent abuse is reviewed.

Updating federal standards for toxicants: n-Hexane as the model

Regulatory agencies commonly set standards for a myriad of chemical and physical hazards, with a special focus on carcinogens. This focus can obscure the need to update previously set standards for non-carcinogenic hazards in response to new scientific data. This paper considers n-hexane as a representative chemical hazard: the occupational standard of 500 ppm over an 8 hr time weighted average for a 40 hr week as set in 1948. In the last 12 yr, n-hexane has been shown to cause adverse effects on the peripheral and central nervous systems, the eye, and the respiratory tract. Yet, these new data have not, as yet, been incorporated into a revised standard for n-hexane. The lack of scientific data on the carcinogenicity of n-hexane may be an underlying reason explaining the failure of regulatory agencies to revise their standards. Perhaps, the most troubling problem to regulatory agencies is the sheer magnitude of the chemical regulatory burden. Research should proceed on developing meaningful categories or groupings both for the initial setting of standards and for revising existing standards.

Neurological sequelae of toluene abuse

1 Twenty patients, aged eight to 14 years, were admitted to hospital over a six year period with an acute encephalopathy following toluene abuse. 2 In all cases toxicity was confined to the central nervous system. Electroencephalography performed in ten patients was abnormal in three. 3 Fourteen patients made a complete recovery, five had evidence of personality impairment but were lost to follow-up, one had a persistent cerebellar ataxia one year after admission, despite absence of exposure to toluene. 4 Solvent abuse may be impossible to establish on history, as in six of these patients. Blood assay of toluene is vital in such cases, as is an awareness that toluene abuse may lead to acute encephalopathy.

Experimental neurotoxicity and urinary metabolites of the C5-C7 aliphatic hydrocarbons used as glue solvents in shoe manufacture

Rats were intermittently exposed (9 to 10 h/d, 5 to 6 d/week) to controlled concentrations of single analytical grad solvents in ambient air. After periods ranging from 7 to 30 weeks the animals were perfused with glutaraldehyde and samples of nerves were processed for light microscopy of sections and of teased fibers. Animals treated with n-hexane at 5000 ppm (14 weeks) or 2500 ppm (30 weeks) developed the typical giant axonal degeneration already described in rats treated continuously with 400 to 600 ppm of the same solvent for 7 weeks or more. No such alterations were found in rats subjected to the following intermittent respiratory treatments: n-hexane 500 ppm (30 weeks) or 1500 ppm (14 weeks), cyclohexane 1500 or 2500 (30 weeks), n-pentane 3000 ppm (30 weeks), n-heptane 1500 ppm (30 weeks), 2-methylpentane 1500 ppm (14 weeks), and 3-methylpentane 1500 ppm (14 weeks). The following metabolites were found in the urine of rats according to treatment (in parenthesis): 2-methyl-2-pentanol (2-methylpentane); 3-methyl-2-pentanol and 3-methyl-3-pentanol (3-methylpentane), 2-hexanol, 3-hexanol, gamma-valerolactone, 2,5-dimethylfuran, and 2,5-hexanedione (n-hexane). 2-Hexanol was found to be the main urinary metabolite of n-hexane, while 2,5-hexanedione was present only in a lesser proportion. This feature of rat metabolism suggests that in this species 2,5-hexanedione reaches an effective level at its site of action during intermittent respiratory treatment with n-hexane with difficulty and explains the high concentrations necessary to cause polyneuropathy in rats subjected to this treatment.

N-Hexane- and methylethylketone-induced polyneuropathy. Abnormal accumulation of glycogen in unmyelinated axons. Report of a case

This report presents the ultrastructural nerve study of a patient with sensorimotor neuropathy by a shoe glue containing an association of n-hexane and methylethylketone. Giant axons, distended by microfilamentous proliferation typical of such cases of neuropathy, were found in significant amounts. An unusual histological feature of this case was the considerable distension by a marked accumulation of glycogen granules in certain unmyelinated axons. Such a lesion has never been described in neuropathy induced by industrial agents.

Toxic polyneuropathy due to n-hexane

Three women developed a predominantly motor polyneuropathy following industrial exposure to an adhesive agent containing 80.4% of n-hexane as a volatile substance. Histological and electron-microscopic studies were carried out on sural nerve and on soleus muscle. In the nerve, there were polymorphous changes in both myelin sheaths and axons of large diameter fibres. Irregular and swollen myelin sheaths and segmental swelling of axons with dissolution of neurotubules and evident increase of neurofilaments were frequently observed. Polymorphous inclusion bodies were often present in Schwann cell cytoplasm. The small myelinated and unmyelinated fibres did not show significant changes. The muscles showed denervation atrophy and focal degenerative myopathic changes, with presence of lymphocytic infiltrates and phagocytosis. This study confirms the noxious effect of n-hexane on the peripheral nerve, with development, in our cases, of a toxic polyneuropathy and denervation muscular atrophy with consistent myopathic changes.

Effects of acetone, methyl ethyl ketone and methyl isobutyl ketone on a match-to-sample task in the baboon

Acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) were evaluated for effects on a delayed match-to-sample discrimination task in the juvenile baboon. The animals were exposed to 1/2 the threshold limit value (TLV) of each gas for 24 hr per day during a 7-day period. They were also exposed to a combination of MEK and MIBK at the same exposure concentrations. Each exposure condition affected accuracy of performance minimally but resulted in increased and decreased extra responses during the delay intervals. Response times were slowed under acetone, MEK or MIBK. In contrast to the effects of the individual gases, exposure to a combination of the same doses of MEK and MIBK produced a consistent increase in extra responses during delay and a concomitant decrease in response times. Changes in tissue uptake and metabolism are suggested as possible mechanisms to explain this observation.

Effects of acetone and toluene vapors on multiple schedule performance of rats

Six rats were trained to press a lever for a liquid food reward on a multiple fixed ratio--fixed interval (FR--FI) schedule of reinforcement. When lever-pressing rates became relatively stable, the animals were exposed to 150 ppm of either acetone or toluene for duration times of 1/2, 1, 2 and 4 hr. Exposures were conducted at least three weeks apart. Acetone produced minimal changes on the FR--FI responding during the 1/2 hr exposure. During the 1 hr exposure period, both FR and FI rates increased while during the 2 hr exposure, both FR and FI responses decreased below control levels. During the 4 hr exposure FI responses approximated control levels for 2 rats and were above the control level for the third animal while FR rates were below controls for 2 of the 3 subjects. Rate changes under toluene were generally qualitatively similar to those produced by acetone. An initial enhancement of FR and FI rates occurred during the shorter exposure periods followed by a decrease in rates during the longer exposure periods.

Experimental studies on hydrocarbon neuropathies induced by methyl-ethyl-ketone (MEK)

An outbreak of neuropathies among Berlin solvent sniffers was closely related to the denaturation by methyl-ethyl-ketone (MEK) of the mixture used. The solvent was composed of n-hexane, toluene and ethyl-acetate. Nervous system responses to chronic repeated exposure to 10,000 ppm pure n-hexane, 10,000 ppm MEK/n-hexane (ratio 1:9) and 6000 ppm pure MEK were investigated in rats. Motor neuropathy of the dying back type with giant swelling of axons in the peripheral and central nervous system developed in animals exposed to MEK/n-hexane and n-hexane. Severe potentiation of n-hexane neurotoxicity and shortened onset of morphological and clinical signs were demonstrated in animals exposed to MEK/n-hexane. MEK alone did not produce neuropathy under these conditions. The findings suggest that commercial solvent mixtures containing MEK/n-hexane should be avoided.

Studies on the etiology of the experimental neuropathy from industrial adhesive (glues)

Chickens treated by paintbrushing with glue distillate (used in shoe industries), hydrocarbon mixture and TOCP in hexane, developed paralysis (4/5); in these, we have demonstrated a diffuse degeneration of the myelinic sheath of the peripheral and central neurites. Besides TOCP, cyclohexane (because of its higher concentration in the glue distillate and in the hydrocarbon mixture) may be indicated as responsible for occupational neuropathy.

Some aspects of the mechanisms by which industrial solvents produce neurotoxic effects

A Short Review is given of the biochemical neurotoxic mechanisms of common industrial solvents of various structures. The acute effects of organic solvents may be caused by their direct action on the nerve cell membrane and energy metabolism, whereas chronic neurotoxic effects may be explained by the formation of chemically and biologically reactive intermediates. The stability of the toxic metabolites appears to correlate with the development of neuropathy although this is structuredependent. The role of reactive intermediates is also emphasized by the potentiating effect of the induction of the cytochrome P-450 complex.

Toxic polyneuropathies in Italy due to leather cement poisoning in shoe industries. A light- and electron-microscopic study

The peripheral nerve biopsy specimens of 4 cases of toxic polyneruopathies induced by exposure to leather cement in shoe industries were studied. Analysis of the cements used in the manufacturing process proved them to contain n-hexane as a volatile substance. Light- and electron-microscopic examination of nerve biopsies showed segmental swelling of axons due to the accumulation of packed filaments and thinning of the overlying myelin sheath. Neither active nerve fibre degeneration nor regeneration were frequently seen. It has been suggested that features of so-called giant axonal neuropathy are the most common pattern of peripheral nerve degeneration in chronic n-hexane intoxication.

Toxic polyneuropathies after sniffing a glue thinner

In West Berlin in the autumn of 1975 through the following 5 months we observed 18 juvenile patients who had a toxic polyneuropathy and had sniffed a glue thinner. The neurological picture consisted of a symmetrical, progressive, ascending, mainly motor, polyneuropathy with pronounced muscle atrophy and characteristic vegetative alterations. The height of the disease was reached after 1 1/2-2 1/2 months and was characterized by tetraplegia in 7 patients. After 8 months all patients still had a motor deficit. Nerve biopsy showed paranodal axon swelling, dense masses of neurofilaments and secondary myelin retraction. The neurological and morphological data correspond to the "glue sniffer's neuropathy" and the n-hexane and MBK polyneuropathy after industrial exposure, as described in 10 cases to date. However, there was no MBK in the glue thinner. The polyneuropathies occurred in close time relation with the denaturation of the thinner with MEK (2-butanone). It is concluded from the data n-hexane and MBK have a common toxic mechanism with primary axonal changes and that there is an additional synergistic effect of MEK.

Toxic polyneuropathy of shoe-industry workers. A study of 122 cases

The toxic polyneuropathy observed in a group of shoe-industry workers in Italy was clinically characterised by a symmetrical prevalently distal motor deficit, with occasional marked weakness of pelvic girdle muscles, and frequently by only subjective sensory symptoms; non-specific disturbances usually preceded neurological signs. Subclinical cases of 'minimal' chronic neuropathy, characterised by alterations of a neurogenic type in the EMG without a reduction of motor nerve conduction velocity, were also observed. Worsening of the clinical picture, with further lowering of nerve conduction velocity, was noted in some cases up to four months after removal from the toxic environment. In the most severe cases clinical recovery took up to three years. The electromyographic and electroneurographic features were consistent with a mixed axonal neuropathy, with clear prevalence of the damage in the distal part of the nerve (dying-back neuropathy). Volatile substances, such as n-hexane and other low boiling point hydrocarbons found in high percentage in solvents and glues, are suggested as the causative agent.