Posterior fossa involvement in the diagnosis of adult-onset inherited leukoencephalopathies

Adult-onset leukodystrophy with vanishing white matter: a case series of 19 patients

BACKGROUND

Leukodystrophy with vanishing white matter (LVWM) is an autosomal recessive disease with typical pediatric-onset caused by mutations in one of the five EIF2B genes. Adult-onset (AO) cases are rare.

METHODS

In this observational study, we reviewed clinical and laboratory information of the patients with AO-LVWM assessed at two referral centers in Italy and Portugal from Jan-2007 to Dec-2019.

RESULTS

We identified 18 patients (13 females) with AO-LVWM caused by EIF2B5 or EIF2B3 mutations. Age of neurological onset ranged from 16 to 60 years, with follow-ups occurring from 2 to 37 years. Crucial symptoms were cognitive and motor decline. In three patients, stroke-like events were the first manifestation; in another, bladder dysfunction remained the main complaint across decades. Brain MRI showed white matter (WM) rarefaction in all cases, except two. Diffusion-weighted imaging documented focal hyperintensity in the acute stage of stroke-like events. 1H-spectroscopy primarily showed N-acetyl-aspartate reduction; 18fluorodeoxyglucose-PET revealed predominant frontoparietal hypometabolism; evoked potential studies demonstrated normal-to-reduced amplitudes; neuro-ophthalmological assessment showed neuroretinal thinning, and b-wave reduction on full-field electroretinogram. Interestingly, we found an additional patient with LVWM-compatible phenotype and monoallelic variants in two distinct eIF2B genes, EIF2B1 and EIF2B2.

CONCLUSIONS

AO-LVWM presents varying clinical manifestations at onset, including stroke-like events. WM rarefaction is the most consistent diagnostic clue even in the latest onset cases. Spectroscopy and electrophysiological features are compatible with axon, rather than myelin, damage. Cerebral glucose metabolic abnormalities and retinal alterations can be present. LVWM might also be caused by a digenic inheritance affecting the eIF2B complex.

Brainstem lesions: MRI review of standard morphological sequences

MRI signal changes in the brainstem are observed in a multitude of disorders including vascular diseases, neoplastic lesions, degenerative diseases, inflammatory disorders, metabolic diseases, infections, and trauma. In some diseases, brainstem involvement is typical and sometimes isolated, while in other diseases, brainstem lesions are only observed occasionally in the presence of other typical extra-brainstem abnormalities. In this review, we will discuss the MRI characteristics of brainstem lesions observed in different disorders associated with frequent and less frequent brainstem involvement. Identification of the origin of the brainstem lesion depends on the exact localisation of the lesion(s) inside the brainstem, the presence and the characteristics of associated lesions seen outside the brainstem, the signal changes on different MRI sequences, the evolution over time of the radiological abnormalities, the history and clinical state of the patient, and other radiological and non-radiological examinations.

Leukoencephalopathy With Predominant Infratentorial Involvement Caused by a Novel ABCD1 Mutation: Does the Spinocerebellar Variant of Adrenoleukodystrophy Exist?

INTRODUCTION

X-linked adrenoleukodystrophy (X-ALD) encompasses several clinical and neuroimaging phenotypes, including cerebral X-ALD, the most common phenotype in children, and adrenomyeloneuropathy, the most common phenotype in adults. A spinocerebellar variant of X-ALD has been described in individuals from the Far East, but the criteria for its diagnosis are unclear.

CASE REPORT

A 35-year-old man from Albania was assessed because of a familial, slowly progressive spastic-ataxic gait associated with neurogenic bladder, sexual dysfunctions, and manic-like behavior. There was no definite clinical feature that suggested cerebellar involvement (eg, cerebellar limb ataxia, nystagmus, and dysarthria). A few months earlier, he had received a diagnosis of Addison disease. Brain magnetic resonance imaging showed a leukoencephalopathy with predominant cerebellum and brainstem involvement, and FDG-PET revealed marked cerebellar hypometabolism. The diagnosis of X-ALD was made because we found an increase of very long chain fatty acids, and a new ABCD1 mutation (c.1627C>T, p.Pro543Ser).

CONCLUSIONS

X-ALD should be included in the differential diagnosis of adult leukoencephalopathies with predominant involvement of infratentorial structures, that is, the cerebellum and brainstem. From a classification perspective, our patient (of white origin), like others (all of Asian origin), should be considered as suffering from a variant of adrenomyeloneuropathy rather than from spinocerebellar X-ALD. Actually, the term "spinocerebellar" or similar ones, such as "cerebello-brainstem dominant form," should be limited to those exceptional cases, in which both the clinical and neuroimaging findings point exclusively (or at least predominantly) to the involvement of infratentorial structures.

Adult Leukodystrophies: A Step-by-Step Diagnostic Approach

Leukodystrophies usually affect children, but in the last several decades, many instances of adult leukodystrophies have been reported in the medical literature. Because the clinical manifestation of these diseases can be nonspecific, MRI can help with establishing a diagnosis. A step-by-step approach to assist in the diagnosis of adult leukodystrophies is proposed in this article. The first step is to identify symmetric white matter involvement, which is more commonly observed in these patients. The next step is to fit the symmetric white matter involvement into one of the proposed patterns. However, a patient may present with more than one pattern of white matter involvement. Thus, the third step is to evaluate for five distinct characteristics-including enhancement, lesions with signal intensity similar to that of cerebrospinal fluid, susceptibility-weighted MRI signal intensity abnormalities, abnormal peaks at MR spectroscopy, and spinal cord involvement-to further narrow the differential diagnosis. ^©RSNA, 2019.

Adult leukoencephalopathies with prominent infratentorial involvement can be caused by Erdheim-Chester disease

BACKGROUND

Leukoencephalopathies with prominent involvement of cerebellum and brainstem, henceforward called prominent infratentorial leukoencephalopathies (PILs), encompass a variety of inherited and acquired white matter diseases. Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis likely under-diagnosed as cause of adult PIL.

METHODS

We reviewed the clinical and laboratory information of ten consecutive sporadic adult patients with PIL of unknown origin, who were investigated for ECD.

RESULTS

There were seven males and three females; mean age at clinical onset was 49.6 years (range 38-59); cerebellar ataxia with or without other neurological symptoms was the only or the main clinical manifestation; diabetes insipidus was present in three individuals. Eight patients had white matter focal supratentorial abnormalities, in addition to the infratentorial white matter changes. Six out of eight patients had spinal cord lesions. Thoraco-abdominal CT showed periaortic sheathing in two patients, whole-body FDG-PET revealed increased glucose uptake in the long bones of the legs in five patients, brain FDG-PET showed overt infratentorial hypermetabolism in one patient. In eight patients, ECD was confirmed by bone scintigraphy, pathological data, or both. Two ECD patients treated with vemurafenib showed a marked improvement of neurological symptoms and brain MRI abnormalities at 1 year follow-up.

CONCLUSIONS

Symptoms of PIL can be the only clinical manifestation of ECD. Adult patients with PIL of unknown origin should undergo investigations aimed at unveiling ECD, including bone scintigraphy and whole-body FDG-PET. The early diagnosis allows starting disease-modifying therapies of an otherwise life-threatening disease.