Longitudinally extensive transverse myelitis: a descriptive clinical study
Background: Transverse myelitis (TM) is a term used to describe inflammation of the spinal cord. A small segment of the spinal cord is usually involved. However, when TM is severe enough to cause T2 weighted hyper-intensities extending across three or more vertebral segments on sagittal spinal magnetic resonance imaging (MRI), it is given the term: longitudinally extensive transverse myelitis (LETM). LETM is an infrequently encountered condition and the incidence of this syndrome is not well described. Recent studies show that the frequency of LETM ranges from 2 to 10% of patients with TM. The causes of LETM can be broadly divided into demyelinating, autoimmune, infectious and miscellaneous. LETM is the most specific radiological finding of the neuromyelitis optica spectrum disorders (NMOSD) and has been extensively described in this condition. NMOSD has been typically found in human immunodeficiency virus (HIV) negative patients. Furthermore, LETM itself is not well described in HIV positive patients. Aims: Firstly, to describe the clinical characteristics and aetiology of patients with LETM in a South African setting. Secondly, to describe LETM in HIV positive patients. Methods: 22 Adult patients presenting with LETM to the division of Neurology of the University of the Witwatersrand were included in this prospective study. Patients were recruited from Charlotte Maxeke Johannesburg Academic Hospital (CMJAH), Chris Hani Baragwanath Academic Hospital (CHBAH) and Helen Joseph Hospital (HJH). The study population were recruited over approximately 2 years. Results: The aetiology of LETM in this population was as follows: 15 patients were diagnosed as NMOSD, 4 patients had an infective cause, 1 had an ischaemic myelopathy and 2 had an unknown or idiopathic LETM. In terms of HIV status, 15 subjects were HIV negative and 7 were HIV positive. Of those that were HIV positive, 3 patients had tuberculous myelitis causing LETM and 4 met NMOSD diagnostic criteria. Conclusion: NMOSD is a common cause of LETM and is suggested by cervical involvement compared to a thoracic LETM which suggests non-NMOSD causes. In HIV positive patients with LETM, NMOSD is less likely and alternative diagnoses should be excluded, especially infective causes. Nevertheless, NMOSD occurs in HIV positive patients and may be associated with a high viral load.
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment for the degree of Master of Medicine in the division of Neurology Johannesburg 2017.