Response to letter to the editor regarding “Assessment of serum S100B and neuron specific enolase levels to evaluate the neurotoxıc effects of organıc solvent exposure” in Clinical Toxicology 2013; (doi:10.3109/15563650.2013.820831)

To the Editor:

In our study, we did not consider to give the control group's laboratory results as short-term air monitoring results of the workplaces that were found to be below recommended exposure limits of National Institute for Occupational Safety and Health (NIOSH).¹ Supporting this, the control group's toxicology test results were significantly lower (mostly undetectable) compared to those of the exposed group. On the other hand, request for demographic characteristics of exposed group is justifiable. But we can easily say that, when the exposed and control groups were compared for alcohol consumption and cigarette smoking, there was no difference between groups and in the exposed group, alcohol consumption was very low and cigarette smoking did not exceed 10 patients, not more than 5 pack years. In the literature, we have found no study which emphasizes a relationship between NSE/S 100B and these levels of cigarette smoking and alcohol consumption.

Carpal tunnel syndrome (CTS) is a complex of symptoms and signs such as paresthesia and pain in the median nerve innervation area.² In the evaluation of a peripheral neuropathy of a toxic exposure, (our) neurologists determined timing measures, distal latency, conduction velocity, and F-wave latency of median, ulnar, radial (in upper extremities), peroneal, and suralis nerves (in lower extremities).³ For this reason, in daily practice of a neurologist, it is not hard to find that a neuropathy is a consequence of CTS or other causes.

A biomarker is accepted as a measurable and supportive indicator of a disease and can be divided into three groups as biomarkers of exposure, effect, and susceptibility. In clinical practice, it is very hard to find a thorough relation between an ongoing or past exposure of a toxic substance and peripheral or central neurological disorder. Especially in chronic and low-dose solvent exposure, it is very difficult to detect it in biological samples because of rapid elimination from the body.⁴ In this case, any probable correlation should be taken into account.⁵ So, in our opinion, from the neurological point of view, any parameter which is weakly or strongly related to these disorders should be accepted, as a valuable tool for clinical evaluation or diagnosis of a toxic exposure.