Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

: 1999  |  Volume : 9  |  Issue : 2  |  Page : 83--84

Toxic encephalopathy due to chronic toluene abuse : Report of a case with magnetic resonance imaging

Purushottam Dixit, SR Nadimpalli, Robert P Cavallino 
 Department of Radiology, Illinois Masonic Medical Centre 836 Wellington Avenue, Chicago, IL 606575193 USA

Correspondence Address:
Purushottam Dixit
Department of Radiology, Illinois Masonic Medical Centre 836 Wellington Avenue, Chicago, IL 606575193 USA

How to cite this article:
Dixit P, Nadimpalli S R, Cavallino RP. Toxic encephalopathy due to chronic toluene abuse : Report of a case with magnetic resonance imaging.Indian J Radiol Imaging 1999;9:83-84

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Dixit P, Nadimpalli S R, Cavallino RP. Toxic encephalopathy due to chronic toluene abuse : Report of a case with magnetic resonance imaging. Indian J Radiol Imaging [serial online] 1999 [cited 2021 Jan 22 ];9:83-84
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Toluene is one of the most widely used and abused of the organic solvents. It is a major component of many paints, lacquers, adhesives, inks and cleaning liquids. This substance is popular due to its euphoric effect and easy availability. Chronic abuse results in persistent neurologic abnormality with variable spontaneous recovery following abstinence. The nervous system effects are considered by some authors to be due to a combination of demyelination and axonal degeneration [1]. There are only a few reports in literature discussing radiological evaluation of cases of toluene abuse using MR. It is believed that the abnormalities seen on MR are due to either increased water content of the white matter or subtle toluene-induced metabolic changes in myelin. Even though a certain predictable pattern of abnormalities is usually seen we now report a case of chronic toluene abuse with uncommon and peculiar manifestations on MR.

A twenty-nine-year old white man presented with complaints of worsening coordination involving all four limbs, associated with tremors off and on, for a period of eight months. The patient had a history of toluene sniffing since the age of sixteen. He stopped five months prior to presentation, with only slight improvement in his ability to walk. He complained of continued unsteadiness and staggering gait. There was no history of sensory deficits, pain or memory loss. Neurologic examination revealed dysarthric speech with intact cranial nerves, except for saccadic eye movement. Muscle strength was 5/5 in all four limbs and the deep tendon reflexes were well preserved. Sensory examination was completely normal. The patient's gait was ataxic and broad based with a positive finger-nose test and an equivocal Romberg test. Significant tremors were present at rest, which increased on intention. There was lack of co-ordination of rapid alternating movements. The rest of the physical exam was non-contributory. Extensive laboratory workup including RPR test for syphilis, ESR, B12 levels, thyroid profiles, urine and blood toxicity screens were negative. An MR of the brain without and with contrast enhancement was performed. Non-contrast scans included T1W sagittal and coronal (750/25/2)(TR/TE/Excitations) and T2W axial (3000/110/2) images. Contrast enhanced T1W sagittal, axial and coronal (500/25/2) images were obtained following bolus intravenous administration 0.1 mmol/ kg body weight Gd-DTPA. The following findings were observed:

diffuse cerebral, cerebellar and brainstem atrophy. bilaterally symmetrical hypo intensities involving the thalamus on T2W images. These were isointense on T1W images without enhancement. abnormal hyperintensity in the internal capsule on T2W images. diffuse abnormal signal in the white matter with indistinct grey-white matter differentiation on T2W images.

Toluene is an example of a typical lipophilic substance that accumulates in the myelin for a long time, leading to severe functional disturbances [2]. Pathological changes occurring in the brain are due to prominent degeneration and gliosis of the ascending and descending long tracts, in addition to diffuse demyelination and atrophy. The clinical features of toluene abuse include neuro-behavioural, cerebellar, brain stem and pyramidal tract abnormalities. Neuro-behavioural abnormalities are the most disabling and frequent feature and may herald the onset of permanent CNS dysfunction. Other persistent neurologic sequelae include cerebellar ataxia, cognitive dysfunction, optic neuropathy, sensori-neural hearing loss and equilibrium disorders. The most common syndrome is multifocal CNS involvement. Evaluation with CT and MR usually reveals cerebral, cerebellar and brainstem atrophy [1],[2], which is consistent with our findings. Other MR findings include loss of grey-white matter, differentiation and increased periventricular signal intensity on T2W sequences [1], which were also demonstrable in the present patient. Bilaterally symmetrical hypo intensities in the thalamus, seen in this patient's MR were however a very unusual and peculiar finding and may have been due to increased iron deposition in these areas. Only a few recent studies mention these thalamic hypo intensities [1], [4], [5] which may be considered radiological curiosities, seen especially in the setting of toluene abuse. Another isolated case report mentions atrophy of the corpus callosum [3], which was not found to be the case with our patient. However the same report [3] mentions abnormal signal intensity in the internal capsule which was demonstrable in our patient. The difference in MR findings can be ascribed to a number of reasons including differences in race, intrinsic enzymatic metabolism and duration of toluene abuse. Multisubstance abuse and co-existing disease were very carefully ruled out in our case by a detailed history and a battery of laboratory tests. However in the absence of a definite history of toluene abuse another important differential diagnosis is a neurodegenerative process or leukodystrophy. These conditions are also associated with diffuse white matter abnormality, cerebral atrophy and iron deposition in the basal ganglia.

Another important consideration in cases of substance abuse is HIV related encephalopathy. In the presence of cerebral atrophy and diffuse white matter changes it not only assumes importance as a radiological differential diagnosis but should also raise the index of suspicion for HIV infection.

In conclusion we present an unusual MR finding only recently mentioned in the radiologic literature in a case of chronic toluene abuse which, even though a major public problem, is radiologically not well investigated [1],[3]. These unusual findings assume greater significance and may confound the radiologist especially in the absence of adequate history.


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