Teaching NeuroImages: A rare genetic cause of spastic paraparesis

A 37-year-old female born in India developed a gradually progressive gait disturbance and bilateral lower limb stiffness beginning at the age of 15 years. There was no relevant family history or consanguinity. Cranial nerve examination was normal. She had symmetrical spastic paraparesis, left ankle clonus and extensor plantar response. She walked with a spastic gait. Magnetic resonance imaging of brain revealed bilateral asymmetric leukoencephalopathy, and areas of low T2 and gradient echo signal in the subcortical white matter, basal ganglia and thalami (Figure). Spinal imaging was normal. Computed tomography confirmed large volume calcification of caudate, putamen, thalamus and subcortical white matter. She was compound heterozygous for n.*5C>T and n.74G>A variants in SNORD118 consistent with a diagnosis of leukoencephalopathy with intracranial calcification and cysts (LCC), a rare autosomal recessive cerebral microangiopathy.¹ Seizures and developmental delay are the most common presentations of LCC, but pyramidal and extrapyramidal features may also be seen.²

Figure 1.

(A,B) Baseline Axial T2 Magnetic resonance (MR) of head shows asymmetric leukoencephalopathy with multifocal low signal areas in basal ganglia and thalami that bloom on Gradient echo (C);(D,E) Computed tomogram confirm corresponding extensive multifocal calcification ; (F) Follow-up axial T2-weighted MR shows development of periventricular cysts (black arrowhead).