Epilepsia partialis continua in mitochondrial dysfunction: Interesting phenotypic and MRI observations

Abstract

An 11-year-old girl manifested with photophobia, ptosis, external ophthalmoplegia, hypotonia, weakness of proximal limb muscles, hyporeflexia, and generalized seizures (six months). Her elder sister had had uncontrolled seizures and photophobia and died at seven years of age. In the patient, serum lactate was high (55 mg/dl). Muscle biopsy revealed characteristic ragged red and ragged blue fibers, diagnostic of mitochondrial cytopathy. Sequencing of the complete mitochondrial genome of the DNA obtained from the muscle biopsy of the patient did not show any characteristic mutation. Four months later, the girl was admitted with a one-week history of epilepsia partialis continua (EPC). EEG revealed Periodic Lateralized Epileptiform Discharges (PLEDs), once in 2-4 seconds, over the right temporo-occipital leads. MRI revealed signal change of right motor cortex, which had restricted diffusion. MR spectroscopy (MRS) from this region revealed lactate peak. EPC remained refractory to multiple anti-epileptic drugs, immuno-modulators, coenzyme-Q, and carnitine. This thought provoking report expands the spectrum of mitochondrial cytopathies.

Keywords: Chronic progressive external ophtalmoplegia; MRI; Mitochondrial Encephalopathy with Ragged Red Fiber; epilepsia partialis continua; mitochondrial dysfunction; periodic lateralized epileptiform discharges.

Figure 1

(a-c) Biopsy of biceps showing ragged appearing fibers on Haematoxylin and Eosin stain (a) which on MGT (b) and SDH (c) are ragged red and ragged blue respectively d) EEG with Periodic Lateralised Epileptiform Discharges (PLEDs) - once in 2-4 seconds, over right>left temporo-occipital leads e) Axial CT scan with bilateral basal ganglia calcification

Figure 2

(a) Axial MRI (FLAIR) showing hyperintense right motor cortex b) MR Spectroscopy showing a lactate peak at 1.4 c, d) Diffusion weighted image (DWI) revealing hyperintensity in the right motor cortex which was hypointense on apparent diffusion coefficient (ADC) suggesting restricted diffusion