Background

Pruritus, better known as itch, is ‘an unpleasant cutaneous sensation provoking the desire to scratch’.1 It is typically caused by pruritogens that activate nerve endings in cutaneous and transitional tissues (eg, conjunctivae, anal mucosa) and serves a protective function against noxious stimuli.

Itch can also occur with diseased or malfunctioning pruritogenic neurones in the absence of a pruritogen—a symptom termed neuropathic pruritus or neuropathic itch.2 Neuropathic pruritus is a well described but under-recognised symptom of neurological disorders. The site of involvement may be (i) peripheral nerve and root, (ii) spinal cord or (iii) brain. It may accompany a variety of peripheral and central neurological disorders, including postherpetic neuralgia, peripheral neuropathy, trigeminal neuralgia, traumatic nerve injury, complex regional pain syndrome, multiple sclerosis and stroke.3

Neuromyelitis optica is a relapsing inflammatory astrocytopathic disorder affecting predominantly the optic nerves and spinal cord. It is associated with antiaquaporin-4 immunoglobulin G (AQP4-IgG) in up to 70% of patients. Spinal cord involvement typically presents as a longitudinally-extensive transverse myelitis with associated sensorimotor and sphincter dysfunction. Sensory symptoms such as numbness, dysaesthesia, pain and tonic spasms are common.4 This report highlights neuropathic pruritus as an under-recognised feature of neuromyelitis optica.

Case presentation

A 45-year-old woman with no previous medical history presented with a 4-day history of unexplained nausea, vomiting, hiccup and vertigo. On the fourth day, she developed bilateral forearm itching. Over the following 3 days, she developed rapidly progressive weakness from the chest down, ultimately resulting in complete paraplegia, sensory loss and loss of both bladder and bowel function. She also developed weakness in both arms, worse on the left side.

She was admitted 3 days after the onset of her nausea and vomiting, which subsided a day later. However, the itching …