Stroke Patients after repetitive Transcranial Magnetic Stimulation (rTMS)–Alterations of Tryptophan Metabolites in the Serum

Abstract

Repetitive transcranial magnetic stimulation (rTMS) as a new non-invasive painless procedure has been tested for augmentation of motor performance and reduction of spasticity in post-stroke patients. Stroke patients (N = 34) were recruited for rTMS treatment and brain activity analysis (EEG) was performed before and after rTMS. The effect of rTMS was evaluated using National Institute of Health Stroke Scale (NIHSS), Barthel – Index and Ashworth Scale. The content of L-tryptophan (L-TRP), L-kynurenine (L-KYN), kynurenic acid (KYNA) and anthranilic acid (ANA) was determined in the serum of stroke patients before the 1st, after the 5th and after 10th rTMS application using high performance liquid chromatography. In a separate experiment, L-TRP metabolites were determined in the serum of an independent group of stroke patients (N=47) and control subjects (N=6). The content of L-TRP and L-TRP metabolites in the serum of stroke patients was significantly increased, L-TRY was 121% of CO; L-KYN 161% of CO, p<0.015; ANA 280 % of CO, p<0.001; KYNA 243% of CO, p<0.001, compared to control subjects. Similar changes were found in stroke patients recruited for rTMS. After the 10th rTMS treatment L-KYN and ANA levels increased moderately but significantly in the serum and it was L-KYN 107%, p<0.01; ANA 110%, p=0.055, versus the value before 1st rTMS, respectively. The ratios L-KYN/TRP and ANA/KYNA increased moderately but significantly after the 10th rTMS. Creatin kinase and prolactin levels were in normal range during rTMS. Stroke patients treated with rTMS have shown a significant enhancement of motor performance and moderate reduction of spasticity. The alteration of ANA/KYNA ratio after rTMS might be of significance with respect to the clinical improvement of patients. The present study gives favour for rTMS as a means for neurorehabilitation of patients after stroke. Notable, the management of therapies following rTMS are of importance for an improvement of hand and fingers activities, as observed within this study.