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Abstracts: Neurological Damage Due to Exposure
to Neurotoxic Solvents

1)  Audiological disturbances caused by
long-term exposure to industrial solvents.

2)  Long-term follow up of workers exposed to solvents.

3)  Are deficits in the equilibrium system relevant
to the clinical investigation of solvent-induced neurotoxicity?

4) Otoneurological findings in psycho-organic
syndrome caused by industrial solvent exposure.

5) Neurospect in neurotoxic chemical exposure demonstration
of long-term functional abnormalities.

6) Neurotoxicity in single photon emission computed toomography
brain scans of patients reporting chemical sensitivities.

1) Audiological disturbances caused by
long-term exposure to industrial solvents.

   Relation to the diagnosis of toxic encephalopathy.

Scand Audiol 1998;27(3):131-6

Niklasson M, Arlinger S, Ledin T, Moller C, Odkvist L, Flodin U, Tham R

Department of Otorhinolaryngology, Head and Neck Surgery, Faculty
of Health Sciences, University Hospital, Linkoping, Sweden.

Sixty workers, consecutively admitted due to suspicion of solvent-induced
chronic toxic encephalopathy (CTE), were investigated with pure-tone
audiometry, determination of speech recognition of monosyllabic words
and distorted speech and cortical response audiometry (CRA).

Eighteen workers not exposed to occupational solvents and noise were
also investigated.

The scores in the distorted speech test were significantly lower and
the CRA latencies were significantly longer in the solvent group than
in the control group. There was no difference between the groups in
the pure-tone and monosyllabic speech recognition tests.

In the solvent group, 19 subjects had one or several pathological
audiological test results (values exceeding the mean result of the
control group by 2 SD).

Independently of the audiological examination all the workers in the
solvent group underwent the traditional clinical assessment of CTE,
which is based on symptoms, history of exposure, clinical neurological
examination and a neuropsychological investigation.

They were classified in three groups -- CTE, incipient CTE and non-CTE.
There was no correlation between these groups and the audiological test

A previous report on vestibular pathology in the same group of subjects
and the present investigation on hearing deficits suggest that long-
term exposure to solvents causes disturbances of the central pathways
in the otovestibular system.

Hitherto, no attention has been paid to these disturbances in the definition
of the CTE syndrome.


PMID: 9728772, UI: 98396973
2) Long-term follow up of workers
exposed to solvents.

Br J Ind Med 1990 Feb;47(2):75-82

Edling C, Ekberg K, Ahlborg G Jr, Alexandersson R, Barregard L,
Ekenvall L, Nilsson L, Svensson BG

Department of Occupational Medicine, University Hospital, Uppsala, Sweden.

Long term occupational exposure to organic solvents may cause
adverse effects to the central nervous system.
This collaborative
study between six Swedish departments of occupational medicine
examines the overall prognosis in terms of working capacity,
symptoms, and psychometric test performance for individuals
occupationally exposed to organic solvents.

After re-analyses of the data from an initial clinical investigation
of 111 men, the subjects were divided into two subgroups: one group
of 65 with symptoms but no impairment on the tests and one group of
46 with toxic encephalopathy (symptoms and test impairment).

At least five years after the initial examination the subjects were
asked to attend a re-examination that included a structured medical
interview and a psychometric investigation.

The results indicate that effects on the central nervous system
persist even when exposure has ceased.

In the group of 46 more men had stopped working and were receiving
sickness or early retirement pensions.

This group also had reduced activity levels with regard to everyday life,
leisure activities, and education or training and more neuropsychiatric

There was no support for the view that a solvent induced toxic
encephalopathy is a progressive disease comparable with presenile
dementia such as Alzheimer's disease or Pick's disease.

If a worker was removed from exposure when he presented
without signs of impairment in intellectual function,
recovery was seen in most cases.

3) Are deficits in the equilibrium system
relevant to the clinical investigation
of solvent-induced neurotoxicity?

Scand J Work Environ Health 1997 Jun;23(3):206-13

Niklasson M, Moller C, Odkvist LM, Ekberg K, Flodin U, Dige N,

Department of Otorhinolaryngology, Head and Neck Surgery,
Faculty of Health Sciences, University Hospital, Linkoping, Sweden.

OBJECTIVES: The diagnosis of solvent-induced chronic toxic
encephalopathy is commonly based on case histories of exposure
to solvents, symptoms, and deficits on psychometric tests.

It has previously been demonstrated that long-term solvent-exposed
workers have disturbances of the equilibrium system.

The correlation between these disturbances and the diagnosis of
chronic toxic encephalopathy has been analyzed in the present study.

MATERIAL AND METHODS: Sixty men, consecutively admitted
due to the suspicion of this syndrome, were investigated and classified
into 3 groups -- solvent-induced chronic toxic encephalopathy, incipient
chronic toxic encephalopathy and nonchronic toxic encephalopathy.

They were all examined using an otoneurological test battery,
including analysis of saccades, smooth pursuit, visual suppression
of the vestibular ocular reflex, and dynamic posturography.

RESULTS: Compared with healthy referents several of the subjects,
even in the nonchronic toxic encephalopathy group, showed a reduced
visual suppression ability, a prolonged latency of saccades, and
pathological posturographic results.

Some otoneurological tests correlated with the duration of exposure
and the results of psychometric tests representing memory and
perceptual skills.

Nevertheless, there was no significant group correlation between
the otoneurological findings and the diagnosis of chronic toxic

CONCLUSION: Disturbances revealed by an otoneurological
investigation have so far not been considered in the diagnosis
of chronic toxic encephalopathy.

Our results indicate that an otoneurological test battery adds worthwhile
information about lesions within the brainstem-cerebellar complex
not revealed by a psychometric investigation.
4)  Otoneurological findings in psycho-organic
syndrome caused by industrial solvent exposure.

Acta Otolaryngol (Stockh) 1989 Jan-Feb;107(1-2):5-12

Moller C, Odkvist LM, Thell J, Larsby B, Hyden D, Bergholtz LM, Tham R

Department of Otolaryngolgy and Head and Neck Surgery,
University Hospital, Linkoping, Sweden.

Nine subjects with long-term (8-30 years) occupational exposure to
industrial solvents and a confirmed diagnosis of psycho-organic syndrome
(POS) have been studied with audiological and otoneurological test
batteries. The results were compared to a matched control group of
nine industrial workers not exposed to solvents and to normal data
from healthy volunteers.

In the clinical examination, the Romberg test identified 5/9 workers
as pathologic and concurrently the stabilometry showed significantly
larger sway areas in the POS-group.

In the audiological test battery, the significantly pathologic tests were
discrimination of interrupted speech and evoked cortical responses to
frequency glides (CRA-delta-f).

The saccade test disclosed abnormal findings in 5/9 workers. In the
smooth pursuit test, abnormality was found at some test frequencies
using pseudorandomized stimulus. The VOR-suppression test was
significantly abnormal at all test frequencies. The test battery
used strongly indicates CNS lesions due to industrial solvents.
5) Neurospect in neurotoxic chemical exposure
demonstration of long-term functional abnormalities.

Toxicol Ind Health 1998 Nov-Dec;14(6):813-27

Heuser G, Mena I

Department of Radiology, UCLA-Harbor Medical Center,
Torrance, USA.

Patients who had experienced well-documented neurotoxic
exposure months or years earlier were evaluated.

Seventy-two right-handed adults who claimed continuing
abnormalities of cognitive and memory function were
examined after Xenon-133 inhalation and i.v. HMPAO.

Single photon emission computed tomography (SPECT)
results were statistically compared with age-matched controls.

Bilateral, often asymmetrical, impairment of perfusion
was found, mostly in the frontal, temporal, and parietal lobes.

This hypoperfusion was predominantly left-sided in
young patients and predominantly right-sided in the elderly.

Abnormalities were found months and years after neurotoxic
exposure had ceased. Our findings suggest that NeuroSPECT
can provide evidence of impaired cerebral function and may
therefore help to further define neurotoxic exposure and
its chronic effects.

6) Neurotoxicity in single photon emission
computed toomography brain scans of patients
reporting chemical sensitivities.

1: Toxicol Ind Health 1999 Apr-Jun;15 (3-4):415-20

Ross GH, Rea WJ, Johnson AR, Hickey DC, Simon TR

Summary Brief Abstract Citation MEDLINE ASN.1 XML/SGML
Environmental Health Center-Dallas, Texas 75231, USA.

The subset of patients reporting chemical sensitivity with
neurocognitive complaints usually exhibits specific abnormalities
of  brain metabolism consistent with neurotoxicity, on imaging with
single photon emission computed tomography (SPECT).

These recurrent neurotoxic patterns are characterized by a mismatch
in tracer uptake between early- and late-phase imaging, multiple hot
and cold foci throughout the cortex, temporal asymmetry and increased
tracer uptake into the soft tissues and, sometimes, the basal ganglia.

Previous studies confirm these neurotoxic findings in patients with
neurotoxic chemical exposures and breast implants.

Affective processes such as depression do not, alone, show this pattern.

These abnormalities in SPECT images correlate with documented
neurocognitive impairment.

Controlled challenges to ambient chemicals can induce profound
neurotoxic changes seen on SPECT imaging in chemically sensitive

Detoxification treatment
techniques frequently produce significant
improvement on brain SPECT brain imaging in these patients.

Neurotoxicity appears to be characteristic in many cases of chemical


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