Diversity in MRI findings in leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL)

Background: Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is a rare autosomal recessive disorder with a highly distinctive magnetic resonance imaging (MRI) and spectroscopy pattern. Recent observations indicate that both the extensiveness of MRI abnormalities and the clinical spectrum of the disease are highly variable. In 2012, the criteria for an MRI-based diagnosis of LBSL were revised. This study describes the variety of MRI features in LBSL patients.

Patients and Methods: MR images of 68 patients with genetically proven LBSL in the Amsterdam LBSL database were evaluated according to a standard protocol. Clinical information of 57 patients was collected via questionnaires.

Results: MRI showed variably extensive inhomogeneous or rarely diffuse and homogeneous cerebral and cerebellar white matter abnormalities. In late onset, mild cases, the abnormalities were limited in extent, while in infantile onset, early fatal cases, MRI revealed widespread abnormalities and involvement of additional structures. All major MRI criteria were fulfilled in all but three patients: they lacked the brainstem abnormalities typical for LBSL and involvement of the lateral cortical spinal tracts. The dorsal columns appeared affected in all available spinal cord images.

Conclusions: LBSL has a highly characteristic pattern of MRI abnormalities. However, in the group of patients who fulfill the MRI criteria for LBSL, there is a wide variability in the extent of the abnormalities and in accompanying MRI features. In patients with limited white matter changes, the phenotype is mild, while the few severely affected patients show much more extensive white matter abnormalities.