Mitochondrial diseases are one of the most common groups of neurogenetic disease, with an estimated prevalence of 1 in 4300.¹ There have been many syndromic presentations of mitochondrial disease described over the last few decades, such as chronic progressive external ophthalmoplegia, Leigh syndrome, mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) and neurogenic weakness, ataxia and retinitis pigmentosa (NARP).² Despite their high prevalence and the seemingly classic clinical syndromes, diagnosing mitochondrial diseases is still challenging due to their variable clinical manifestations. Moreover, the clinical phenotype evolves with time; patients could develop additional neurological signs and symptoms or other organ involvement in addition to the presenting clinical syndromes.

Most adult patients present to general neurology clinics with slowly progressive neurological symptoms, such as chronic progressive external ophthalmoplegia, myopathy, neuropathy and ataxia. However, neurologists need to be aware that the acute presentations of mitochondrial disease, such as stroke-like episodes and refractory focal-onset seizures,³ can …