LETTER TO THE EDITOR
|Year : 2020 | Volume
| Issue : 6 | Page : 827-828
Isolated cerebellar involvement in X-linked adrenoleukodystrophy
Department of General Medicine, M.E.S. Medical College, Perinthalmanna, Kerala, India
|Date of Submission||22-Jan-2020|
|Date of Decision||18-Feb-2020|
|Date of Acceptance||17-Mar-2020|
|Date of Web Publication||05-Jun-2020|
Dr. C A Mansoor
Department of General Medicine, M.E.S. Medical College, Perinthalmanna - 679 338, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mansoor C A. Isolated cerebellar involvement in X-linked adrenoleukodystrophy. Ann Indian Acad Neurol 2020;23:827-8
X-linked adrenoleukodystrophy (X-ALD) is a neurogenetic disease. It is the most common peroxisomal disorder caused by mutations in the adenosine triphosphate-binding cassette D1 (ABCD1) gene which maps to Xq28. X-ALD shows considerable phenotypic heterogeneity. The phenotypes of X-ALD include childhood cerebral, adrenomyeloneuropathy, adolescent or adult cerebral, Addison's disease only, and olivopontocerebellar (cerebello-brainstem dominant form). Cerebello-brainstem dominant type is a rare phenotype of X-ALD in which the cerebellum and brainstem are mainly involved accounting for 1–2% of ALD. We report on a patient with X-ALD having isolated cerebellar involvement which was reported only once previously.
A 38-year-old male presented with ataxia for 3 years. He had mild imbalance while walking which did not progress over 3 years. He had no history suggesting upper and lower limb incoordination or dysarthria. The patient had no clinical signs of dorsal column and pyramidal tract dysfunction. He was diagnosed to have Addison's disease at the age of 21 years and was on oral steroids. He was born as the first child of a non-consanguineous union by vaginal delivery at term without complications. His younger brother was also diagnosed to have Addison's disease but died at the age of 20 years (cause unknown). His younger sister and parents were normal. His neurological examination was normal except for mild gait ataxia.
Biochemical parameters including electrolytes, renal function, liver function, and blood counts were normal. Magnetic resonance imaging of the brain showed bilaterally (right more than left) hyperintense lesions on T2-weighted, fluid-attenuated inversion recovery, diffusion-weighted and apparent diffusion coefficient images confined to cerebellar white matter without contrast enhancement [Figure 1]. The rest of the brain parenchyma, brain stem and spinal cord were normal on magnetic resonance imaging. Peroxisomal fatty acid profile was elevated: C22:0 46.46 μmol/L (40–119 μmol/L); C24:0 84.53 μmol/L (33–84 μmol/L); C26:0 4.46 μmol/L (0.45–1.32 μmol/L); C24:0/C22:0 ratio 1.82 (0.57–0.92), and C26:0/C22:0 ratio 0.10 (0.01–0.02). Phytanic acid 0.70 μmol/L (0.12–2.98 μmol/L) and pristanic acid 1.01 μmol/L (0.49–9.88 μmol/L) levels were found to be normal. Genetic studies were not done. The presence of elevated plasma very-long-chain fatty acids (VLCFA) in a male patient with adrenal insufficiency confirms the diagnosis of X-ALD. The family has been counseled that this is a genetic condition with X-linked inheritance. He was continued on prednisolone 5.0 mg morning and 2.5 mg evening for adrenal insufficiency and is under follow up.
|Figure 1: Magnetic resonance imaging of the brain showing bilateral (right more than left) hyperintense lesions on T2-weighted (a and b), diffusion-weighted images (c) and apparent diffusion coefficient (d) confined to cerebellar white matter without contrast enhancement|
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X-ALD is a metabolic disorder characterized by the accumulation of VLCFA in plasma and tissues (a predominantly white matter of the brain, the spinal cord and the adrenal cortex). Besides, six usual phenotypes (childhood cerebral, adrenomyeloneuropathy, adolescent or adult cerebral, Addison's disease only, and olivopontocerebellar), there are reports of several atypical variants. MRI abnormalities involving the frontopontine or corticospinal projection fibers and cerebellar white matter at presentation are more frequent in the adult group. Cerebellar white matter involvement is predominantly seen in adults with X-ALD presenting as spinocerebellar degeneration or olivopontocerebellar atrophy. Brain MRI features were available in 18 cases of an ataxic variant of ALD in the literature. White matter hyperintensities involving the corticospinal tracts and cerebellum were found in 72.2% and 70.6%, respectively. Among 34 patients of the cerebello-brainstem form of X-ALD reported in the literature 28% of cases had T2-weighed hyperintensities in the cerebrum and 78% of the reported cases had lesions in the internal capsule, brainstem and/or cerebellum. Brainstem and/or cerebellar atrophy were found in 62% of the reported cases.
Our case had clinical manifestations and MRI findings confined to bilateral cerebellar white matter. A case of X-ALD with abnormal signals only in the cerebellar white matter and dentate nuclei was reported previously. But this patient had extra cerebellar clinical manifestations in the form of bladder incontinence and memory deterioration. We report a patient with an X-ALD having abnormal MRI signals (T2-weighed hyperintensities) confined to the cerebellar white matter. To the best of our knowledge, only one similar case was reported in the literature previously.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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