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Subjects exposed to industrial solvents may experience vertigo and nausea. Solvents are usually volatile hydrocarbon compounds, which are important parts of everyday life in a modern society. They may also cause neurastenia, personality changes, and reduced intellectual capacity. The syndrome that may develop was formerly named psycho-organic syndrome (POS), but in modern terminology it is called chronic toxic encephalopathy (CTE). The syndrome develops slowly, and during the first years no pathological findings will be found using various test batteries. Somewhat later, when the syndrome still might be reversible, psychometric, auditory, and otoneurologic testing may well unveil disturbances within the posterior fossa structures. Animal experiments suggest one site of effect for solvents to be within the cerebellum and brainstem regions with close relationship to the gamma-amino-butyric acid (GABA) transmission. In the otoneurologic test battery, visual suppression and smooth pursuit are of extreme value, as are some auditory tests such as discrimination of interrupted speech and cortical response audiometry using frequency glides as stimuli. Dynamic posturography and magnetic resonance imaging (MRI) have recently proved valuable in the diagnosis. Research is needed concerning the most efficient test battery for early detection of solvent-induced lesions. During further research it is important to unveil other toxic agents, like heavy metals and alcohol, and their damage to the central nervous system and to make comparisons between these substances and the lesions caused by hydrocarbon solvents.

An MRI installation (Magnetom, Siemens, software version B1 of NUMARIS) working at 0.35 T was used to estimate T1, T2, and relative proton density in the spleen, liver, adipose tissue, and vertebral body in 14 healthy volunteers. Two double-echo sequences were applied for all subjects: TR = 500 ms, TE1 = 35 and TE2 = 70 ms; and TR = 1600 ms, TE1 = 35 and TE2 = 70 ms. The images were sampled in regions of interest and appropriate relaxation expressions fitted to the ROI data yielding relaxation parameters and relative proton densities. Relaxation expressions, included in standard software (Siemens), were compared to more elaborate functions, developed in parallel to this study. The latter were found more appropriate, especially for high T1 values, and gave the following mean values for the four tissues (estimated uncertainty of mean in parentheses) T1 (ms) 915(36), 428(5), 261(7), and 501(11); T2 (ms) 79.7(8.8), 51.0(0.2), 59.8(1.0), and 64.7(0.8); and corresponding relative proton density (rho, arbitrary units) 2088(136), 2182(10), 2915(49), and 2136(21). The uncertainty in the values was estimated in the fitting procedure and does not include systematic errors. The relative noise in the ROIs was about 9% and the reproducibility of the ROI mean values about 8%.

Three patients with advanced adrenocortical carcinoma were treated with a combination of intermittent streptozocin and continuous o,p'DDD. Two patients were treated preoperatively and the primary tumors, initially considered as inoperable, could be resected after 19 and 5.5 months, respectively. In the patient with the longer treatment (35 months), lung and lymph node metastases disappeared and she has no evidence of recurrent disease 6.5 years after start of therapy. One patient was followed by magnetic resonance imaging (MRI) and urinary steroid secretion. The MRI gave a good visualization of the tumor. Measurements of relaxation times showed a significant decrease in T1 values. The urinary steroid profile showed an increased secretion of 3 beta-hydroxy-5-ene steroids and tetrahydro-11-deoxy-cortisol. Treatment with streptozocin and o,p'DDD initially increased 16-oxygenation of dehydroepiandrosterone and androst-5-en-3 beta,17 beta-diol, followed by a decrease in the secretion of all urinary steroids. The third patient received postoperative treatment with no effect on metastatic disease in the lungs, she died 9 months after start of treatment. The therapeutic approach with the combination regimen of streptozocin and o,p'DDD pretreatment plus aggressive surgery has to be further evaluated, as well as MRI and urinary steroid profile as methods to monitor the effect of therapy.