Motor neuron disease (MND) is characterised by degeneration of motor neurons in the brain and spinal cord that usually begins insidiously with focal weakness and subsequent relentless progression to involve most muscles, including the diaphragm ultimately resulting in death due to respiratory paralysis. A significant proportion of patients with MND develop cognitive impairment and behavioural changes. The clinical presentation of AC together with the electrophysiological features was consistent with an upper limb onset MND with features to suggest early cognitive impairment with executive dysfunction. The incidence of MND is approximately 1–2.6 per 100,000 persons annually, while the worldwide prevalence is estimated to be 4–6 per 100,000. The average age of onset of MND is 58–60 years but may vary depending on demographic factors such as geography with much younger age of onset observed in the Chinese population. Early hand dysfunction in MND preferentially affects the ‘thenar hand’, which includes the abductor pollicis brevis and first dorsal interosseous muscles.