title: Median Nerve Somatosensory Evoked Potential in HTLV-I Associated Myelopathy.
abstract: BACKGROUND
  HTLV-I Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) is a progressive Myelopathy that mainly involves the corticospinal tract. Despite pronounced involvement of the lower limbs, patients also have abnormalities in their upper limbs. So, we studied somatosensory-evoked potentials (SSEPs) of the median nerve in HAM/TSP patients to determine the extent of the involvement of the pathway of the central nervous system, especially the cervical spinal cord.
  
  
  METHODS
  In this cross sectional study, 48 patients with HAM/TSP who were referred to Qaem Hospital in Mashhad from October 2010 to October 2011 were evaluated for various indices, including SSEPs of the median nerve for N9, N11, N13, and N20 waveforms and also N11-13 and N13-20 Inter Peak Latency (IPL), severity of disease (based on Osama criteria), disease duration (less or more than 2 years), age, and gender. SPSS software was used for data analysis. The t-test was used for quantitative data, and the chi-squared test was used for the qualitative variables.
  
  
  RESULTS
  Thirty-four patients (70.2%) were females. The mean age was 45.6 ± 14.2 years. About SSEPs indices of the median nerve, N9 and N11 were normal in all patients, but N13 (50%), N20 (16.7%), IPL11-13 (58.3%), and IPL13-20 (22.9%) were abnormal. No significant relationships were found between age, gender, disease duration, and SSEPs indices (p > 0.05), but IPL11-13 and IPL13-20 had significant relationships with disease disability (p = 0.017 and p = 0.01, respectively).
  
  
  CONCLUSIONS
  Despite the lack of obvious complaints of upper limbs, SSEPs indices of the median nerve from the cervical spinal cord to the cortex were abnormal, which indicated extension of the lesion from the thoracic spinal cord up to the cervical spinal cord and thalamocortical pathways. Also, abnormalities in the cervical spinal cord had a direct correlation with the severity of disability in patients with HAM/TSP.
authors.affiliation: Associate Professor of Neurology, Department of Neurology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Boostani
authors.affiliation: Neurologist, Department of Neurology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Poorzahed
authors.affiliation: Resident of Neurology, Department of Neurology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Ahmadi
authors.affiliation: Assistant Professor of Neurology, Department of Neurology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Mellat
keywords: HAM/TSP; HTLV-I; SSEPs; Spinal Cord