A 64-year-old post office worker presented with several years of progressive unsteadiness and tingling sensation in his feet. He was an enthusiastic bodybuilder and had been regularly taking anabolic steroids since his 20s.

On examination he had a broad based gait and Romberg’s test was positive. There was mild dysarthria, dysmetria and an intention tremor. There was wasting evident in his right hand related to a known right ulnar neuropathy. Power was full throughout all limbs but reflexes were reduced. Pin-prick sensation was reduced to the knees and proprioception and vibratory sense were reduced distally.

Neuroimaging revealed cerebellar atrophy and nerve conduction studies an axonal peripheral neuropa- thy. On further questioning the patient disclosed his dietary regime of 4 cans of blended tuna daily for the past 25 years. Mercury levels were significantly raised at 256nmol/l (normal range <25nmol/l). He was advised to stop eating tuna and was prescribed dimercaptosuccinic acid. The level subsequently dropped to 48nmol/l.

Chronic mercury toxicity can present in a variety of ways due to its deposition in different organs (kidneys, liver, brain). In this case, excessive exposure to organic mercury in tuna fish led to a peripheral neuropathy and cerebellar ataxia.