Cortical relay time for long latency reflexes in patients with definite multiple sclerosis

Background: Long latency reflexes (LLR) include afferent sensory, efferent motor and central transcortical pathways. It is supposed that the cortical relay time (CRT) reflects the conduction of central transcortical loop of LLR. Recently, evidence related to the cortical involvement in multiple sclerosis (MS) has been reported in some studies. Our aim was to investigate the CRT alterations in patients with MS. Methods: Upper extremity motor evoked potentials (MEP), somatosensory evoked potentials (SEP) and LLR were tested in 28 patients with MS and control subjects (n=22). The patients with MS were classified according to the clinical form (relapsing-remitting [R-R] and progressive groups). The MS patients with secondary progressive and primary progressive forms were considered as the "progressive" group. CRT for LLR was calculated by subtracting the peak latency of somatosensory evoked potentials (SEP) and that of motor evoked potentials (MEP) by transcranial magnetic stimulation from the onset latency of the second component of LLR (LLR2) (CRT = LLR2 - [MEP latency + N20 latency]) Results: Cortical relay time was calculated as 7.4 +/- 0.9 ms in control subjects. Cortical relay time was prolonged in patients with MS (11.2 +/- 2.9 ms) (p<0.0001). The latencies of LLR, MEP and SEP were also prolonged in patients with MS. Cortical relay time was not correlated with disease severity and clinical form in contrast to other tests. Conclusions: Our findings suggested that CRT can be a valuable electrophysiological tool in patients with MS. Involvement of extracortical neural circuits between sensory and motor cortices or cortical involvement due to MS may cause these findings

Visual evoked potential is superior to triple dose magnetic resonance imaging in the diagnosis of optic nerve involvement

The aim of this study was to evaluate whether VEP is sensitive to optic neuritis (ON) when compared with triple dose orbital MRL Twenty-four relapsing-remitting MS (RRMS) patients were included in the study. Group I (n = 10) patients with acute ON, Group H (n = 8): patients presenting with a current relapse who had the history of ON in the previous relapses. Group III (n = 6): patients presenting with a current relapse but with no history of ON. Neuro-ophtalmological evaluation. VEP investigation and orbital MRI with triple dose (0.3 mmol/kg) gadolinium (Gd) were carried out for all. VEP was found to be 70% sensitive and 12.5% specific to the acute ON, whereas orbital MRI with triple dose Gd was 70% sensitive and 100% specific. In chronic ON, the sensitivity of orbital MRI is 0%, whereas the VEP is still 75% sensitive to chronic optic nerve involvement and can distinguish the pathology 100% specifically. In conclusion, orbital MRI with triple dose Gd is not more sensitive than VEP in determining the acute optic nerve pathologies but it is a 100% specific method The results suggest that VEP is superior to the orbital MRI in determining the chronic optic nerve involvement

Cortical silent period and motor evoked potentials in patients with multiple sclerosis

In order to determine the importance of central motor conduction time (CMCT) and silent period (SP) in patients with multiple sclerosis (MS), we enrolled this clinical and electrophysiological study. Additionally, we planned to compare the correlation between electrophysiological findings and clinical status. We examined 58 patients with definite MS and 31 controls. Patients were classified as relapsing-remitting (n: 37), secondary progressive (n: 21) groups. Eleven out of 58 patients with MS had no neurological findings (subclinical patients). We evaluated CMCT and the duration of SP. Prolonged CMCT latency was shown in 75.2% of patients. We observed SP abnormalities in 69% of patients. In subclinical patients, SP abnormalities (six of 11) were observed more common than CMCT (two of 11). The duration of SP was extremely prolonged in MS patients with cerebellar dysfunction. When the both electrophysiological parameters are taken into account, the abnormality ratio was determined as 89.7%. Our results indicate that CMCT and SP analysis are complementary tests in evaluating motor pathways of patients with MS. We observed a relationship between cerebellar dysfunction and SP prolongation. It is suggested that, SP can be applied in patients with. pure cerebellar dysfunction and it can be a valuable test in subclinical cases with MS. (C) 2002 Elsevier Science B.V. All rights reserved