Whippits, nitrous oxide and the dangers of legal highs

Abstract

Nitrous oxide is increasingly being used as a recreational drug. Prolonged use of nitrous oxide can have disabling neurological sequelae due to functional inactivation of vitamin B₁₂. We present three cases illustrating the neurological complications of using nitrous oxide. Two of these patients received nitrous oxide as a consequence of repeated hospital attendance and the third via 'Whippit' canisters used in cream dispensers, which are now widely available. Two patients developed sensorimotor peripheral neuropathy with demyelinating features with no clinical or imaging evidence of myelopathy, emphasising that not all patients develop subacute combined degeneration of the spinal cord (the typical presentation of functional vitamin B12 deficiency). The diagnosis was based upon the history of nitrous oxide use and raised levels of homocysteine and/or methylmalonic acid. All patients were treated with parenteral vitamin B12 with partial recovery, though two were left significantly disabled.

Keywords: NEUROPATHY; TOXICOLOGY.

Figure 1

Pressurised whipped cream chargers, known as ‘whippits’, are a readily available source of nitrous oxide. They are often used to inflate balloons, from which the gas is inhaled.

Figure 2

Vitamin B₁₂ (cobalamin) is a cofactor in conversion of methylmalonyl coenzyme A (CoA) to succinyl CoA and of homocysteine to methionine. Elevated levels of the substrates methylmalonic acid and homocysteine can be used to detect ‘functional’ B₁₂ deficiency despite normal serum B₁₂ concentrations.