Lhermitte-Duclos disease presenting with atypical positional nystagmus

We describe a patient with dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease) who presented with an acute onset of positional disequilibrium. Video-oculography in the right Hallpike position revealed rightward torsional down-beat nystagmus, initially thought to be right anterior canal benign positional vertigo. However, the presence of spontaneous nystagmus, the persistent character of the positional nystagmus and the absence of fatigability indicated central positional nystagmus, attributable to his right-sided Lhermitte-Duclos disease. These findings emphasise the need for clinicians to reconsider a central cause before diagnosing the rare anterior canal benign positioning vertigo variant.