Predicting the Outcome and Prognosis of Acute Myelitis
Abstract & Commentary
By Susan Gauthier, DO, MS, Assistant Professor of Neurology and Neuroscience, Weill Cornell Medical College. Dr. Gauthier reports no financial relationships relevant to this field of study.
Synopsis: In a cohort of patients presenting with acute myelitis, motor onset and a subsequent relapse were the strongest predictors of residual disability. An abnormal baseline brain MRI was the strongest predictor for conversion to multiple sclerosis.
Source: Gajofatto A, et al. Assessment of outcome predictors in first-episode acute myelitis. Arch Neurol 2010;67:724-730.
Acute myelitis (AM) is a focal inflammatory event of the spinal cord causing a variable degree of sensory, motor, and sphincter dysfunction. AM may lead to significant residual disability and, although partial spinal syndromes have a higher rate of recovery, these patients are generally at risk for developing multiple sclerosis (MS). To further explore the factors associated with specific outcomes in patients with AM, Gajofatto and colleagues reported on a retrospective analysis of 53 AM cases found within their database. Patients were confirmed as having an inflammatory AM with either a contrast-enhanced spinal lesion or with cerebrospinal fluid (CSF) inflammatory markers. The following five outcomes were evaluated in this study: recovery from initial AM; occurrence, location, and time interval of first relapse; final diagnosis at the last follow-up visit, which included monophasic AM, recurrent AM, MS, or neuromyelitis optica (NMO); annual relapse rate; and disability score (EDSS) of at least 2.5, which indicates mild disability in at least two functional systems. In addition, the presence of 14-3-3 protein, cystatin C, and tau protein in the spinal fluid was evaluated in a subgroup of patients.
The majority of the patients recovered fully or remained with only minimal disability. Six patients (11%) had significant residual disability, and symmetric motor dysfunction was strongly predictive of this worse outcome (OR = 48.0, p = 0.01). Most patients (81%) experienced a subsequent relapse; however only five patients were diagnosed with recurrent myelitis and the remaining fulfilled the criteria for clinically definite MS. Overall, 42 patients (79%) eventually met criteria for MS (either by clinical or MRI criteria), and an abnormal brain MRI at baseline, especially having ≥ 3 periventricular lesions, had the strongest association with this outcome. Twelve patients had complete or acute transverse myelitis (ATM), whereas the majority of the patients were diagnosed with partial myelitis (41/53 patients). Interestingly, nine of the ATM patients ultimately developed MS; however, proportionally more recurrent myelitis (60%) began with ATM as compared to MS (21%). Cystatin C was the only CSF marker associated with a worse prognosis, as measured by disability at the last follow-up visit in a subgroup of 11 patients. Overall, the strongest predictors for having neurological disability at follow-up were symmetric motor dysfunction and the presence of at least one relapse.
Commentary
The challenge in caring for patients with AM is the ability to present a reliable prognosis to patients. In this cohort, the majority of patients presented with partial myelitis; therefore, not surprisingly, most patients ultimately fulfilled the criteria for MS. The strongest predictor of developing MS was the baseline brain MRI, which is consistent with previous reported longitudinal studies. Interestingly, 21% of ATM patients developed MS. Therefore, having a severe form of myelitis does not preclude the development of MS and all patients should be evaluated with a brain MRI to properly assess their risk of MS. An increase in cystatin C was associated with a higher rate of disability within a small subset of patients; however, as mentioned in the paper, there have been reports of decreased levels in patients with MS. Given the small number of patients, this will need to be investigated further in a larger cohort of AM patients before a true association can be determined. There are a number of limitations with this study, many of which are inherent to a retrospective analysis, and most important was the selection of patients. The majority of patients within this cohort presented with partial myelitis (77%) and had an abnormal brain MRI (86%); this suggests a bias toward a population at risk for MS as opposed to a cohort representing the full spectrum of AM. The authors speculate that the high rate of conversion to MS in this study is related to the use of the newly accepted MRI-based criteria for the diagnosis of MS, longer follow-up period, and potential selection bias at a specialized MS center.
In a cohort of patients presenting with acute myelitis, motor onset and a subsequent relapse were the strongest predictors of residual disability. An abnormal baseline brain MRI was the strongest predictor for conversion to multiple sclerosis.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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