Short communicationSpinal Cord Hyperintensities in Neurofibromatosis Type 1: Are They the Cord Equivalent of Unidentified Bright Objects in the Brain?
Introduction
Neurofibromatosis type 1 (NF1) is one of the most common inherited neurocutaneous disorders, affecting about 1 in 3000 children.1 The diagnosis of NF1 is based on defined criteria with the patient having two or more distinctive clinical features including cafė-au-lait macules, axillary and/or inguinal freckling, optic pathway gliomas, Lisch nodules, neurofibromas, unique osseous lesions, and a first degree relative with NF1.2 In a majority of patients with NF1, focal areas of T2 hyperintensity are seen on their brain magnetic resonance imaging (MRI).3 These are commonly known as “unidentified bright objects” (UBOs) and are of uncertain etiology. In our neurofibromatosis clinic we have seen children with NF1 and focal T2 hyperintense spinal cord lesions. An association of NF1 with spinal cord hyperintensities has only recently been suggested. We describe seven patients with NF1 and medullary UBOs.4 Prevalence data have not previously been reported.
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Objective
The goals of this study were to (a) determine the prevalence of T2 hyperintense spinal cord lesions in children with NF1 who have undergone spine MRI, (b) describe the imaging appearance of these lesions, and (c) determine if the lesions are static on follow-up imaging which would make them more likely to be the cord equivalent of UBOs rather than low-grade gliomas. This study will help management of patients with NF1 by informing prognosis and the need for follow-up imaging.
Method
We performed an electronic search of our hospital's medical imaging database using Boolean operators and combinations of keywords “neurofibromatosis 1”, “MRI brain”, and “MRI spine” to search medical imaging records of patients with NF1 younger than 18 years of age at the time of imaging performed between February 2014 and April 2017. MRI spines were performed on a 1.5 Tesla Siemens MRI machine with a standardized protocol including multiplanar T1- and T2-weighted sequences. All imaging was
Results
During the study period, 292 children with NF1 were reviewed in the neurofibromatosis clinic. One hundred and fifty-five (53%) children underwent a brain MRI and 72 (25%) underwent a spine MRI. One hundred and twenty-three (79%) showed multiple T2 hyperintense lesions on the brain MRI. We identified six (8%) patients with T2-weighted hyperintensities in the spinal cord. Five children had follow-up imaging. One child did not have a follow-up scan and therefore was not further described. All five
Discussion
In this retrospective study we identified five children with stable focal areas of spinal cord T2 signal hyperintensity. There is only one recently published case series which describes medullary UBOs in patients with NF1.4 Symptoms or signs referable to the lesions were not described, and no child showed progression on follow-up imaging. Only a small percentage of children with NF1 underwent a spine MRI during the study period. In comparison, focal T2 hyperintense lesions in the brain MRI
Conclusions
We suggest that focal areas of T2 signal hyperintensity seen in the spinal cord of children with NF1 represent myelin vacuolization similar to the better described benign focal areas of T2 signal hyperintensity in the brain of the same patient population. Although we are confident that these lesions are benign, given the novel nature of this entity, a short period of interval scanning is recommended until the natural histories of a greater number of cases are described.
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Cited by (4)
Approach to patients with the neoplasms associated with neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis
2020, Neuro-Oncology for the Clinical NeurologistNeurological manifestations of neurofibromatosis: a review
2020, Neurological SciencesBrain MRI analysis of six patients with neurofibromatosis type 1
2019, Chinese Journal of Contemporary Neurology and Neurosurgery
Declarations of interest: The authors declare no conflict of interest.