Leigh Syndrome


KEY FACTS

Terminology

  • a.k.a. subacute necrotizing encephalomyelopathy

  • Genetically heterogeneous mitochondrial disorder characterized by progressive neurodegeneration

Imaging

  • Best imaging: MR with DWI/MRS

    • Bilateral, symmetric ↑ T2/FLAIR corpora striata (putamen > caudate) > globi pallidi, periaqueductal gray matter, substantia nigra/subthalamic nuclei, dorsal pons, cerebellar nuclei

    • Reduced diffusion in regions of acute disease

    • Lactate peak often present on MRS; may be large

    • Uncommon appearance: Predominant white matter disease (simulates leukodystrophy)

Top Differential Diagnoses

  • Profound perinatal asphyxia

  • Mitochondrial encephalopathy, lactic acidosis, stroke-like episodes (MELAS)

  • Glutaric aciduria type 1

  • Wilson disease

Pathology

  • Bioenergetic failure (ATP loss) and production of reactive oxygen species likely key factors in mitochondria-mediated cell apoptosis

  • 50-75% of patients with Leigh syndrome have detectable biochemical or molecular abnormality

Clinical Issues

  • Presentation

    • Psychomotor delay/regression, dystonia/hypotonia, ataxia

    • Other: Ophthalmoplegia, seizures, lactic acidosis

  • Prenatal diagnosis: Chorionic villus sampling (mutations and biochemical defects)

  • Majority present by age 2 years

Axial FLAIR MR shows swelling and abnormal hyperintensity in the caudate heads and putamina
. Foci of hyperintensity are also present in the medial thalami
, a typical location of involvement in Leigh syndrome.

Single voxel proton MR spectroscopy (TE = 26 ms) of the same patient shows a large lactate doublet
at 1.3 ppm. The identification of a lactate peak supports the diagnosis of mitochondrial disease but is variably present.

Axial T2WI MR shows T2 hyperintensity and some swelling of the lentiform nuclei
bilaterally. In addition, the genu
and splenium
of the corpus callosum are affected. Note that foci of unaffected tissue
are present in the putamina; heterogeneous involvement is common.

Axial T2WI MR in the same patient shows T2 hyperintensity of the cerebral peduncles
. This is another common site of involvement in Leigh syndrome.

TERMINOLOGY

Abbreviations

  • Leigh syndrome (LS)

Synonyms

  • Subacute necrotizing encephalomyelopathy

Definitions

  • Genetically heterogeneous mitochondrial disorder characterized by progressive neurodegeneration

IMAGING

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