Nummular headache associated with focal hair heterochromia in a child

Abstract

Nummular headache (NH) is a recently described headache syndrome where continuous or intermittent pain is localised to a coin-shaped region of the skull. NH can be a primary headache disorder or secondary to intracranial or extracranial pathology. We report a four-year-old boy who presented with nummular headache co-localised with a patch of discoloured hair and propose a common aetiology.

Introduction

Nummular headache (NH) is a recently described headache syndrome (1). The pathogenesis is not well understood. We report a child with co-localisation of NH and a patch of discoloured hair.

Case

A four-year-old boy presented with a six-month history of paroxysmal, brief episodes of right parietal pain. These recurred up to four times per day. They occurred without provocation and caused him to scream or cry and clutch the right side of his head. They occurred during enjoyable activities and occasionally woke him from sleep. Over two years of follow-up he was better able to describe the pain and co-operate with clinical exam. He reported focal pain which recurred in episodes of about 5 to 20 seconds. The pain localised to a region about 1–2 cm in diameter beneath a patch of blonde hair. He denied “interictal” local paraesthesia. He was otherwise well, with good general health, normal development and no relevant family history. The patch of blonde hair had been present in the right parietal region from birth and had remained unchanged. Symptoms have remained stable, without treatment, during the past two and a half years.

General and neurologic examinations were normal. He had a patch of heterochromatic (blonde, not white) hair over the right parietal region (see Figures 1 (A) and (B)). There was no local abnormality of skin texture or pigmentation, including with Wood’s light examination. By age six, examination reliably showed a 1–2 cm diameter patch of reduced or altered sensation to light touch and pinprick beneath the patch of blonde hair over the right parietal region.

Figure 1.

Note the patch of blonde hair in the right parietal region, co-localised with the site of recurrent, paroxysmal headache.

Full blood count, erythrocyte sedimentation rate, and antinuclear antibodies were normal. MRI was normal, with no local abnormality of brain, meninges, bone or skin. Microscopy revealed no abnormality of the blonde hairs from the heterochromatic patch.

We presume this is a form of NH and the co-localised patch of heterochromatic hair implies a local, but so far unexplained, pathogenesis.

Discussion

The diagnosis of nummular headache was first “coined” in the medical literature in 2002, and was included as an appendix in the 2004 International Classification of Headache Disorders as an entity in need of additional study (1,2). More than 100 cases have been reported, in patients aged 13 to 72 years (3–7). The pain in NH is localised to a coin-shaped region, typically in one of the parietal regions and rarely both parietal regions. The pain may be continuous or intermittent (5). The continuous pain is of mild or moderate intensity and the episodic pains may be like electric shocks, lancinating or burning (8). The term “primary NH” implies absence of underlying pathology. The term “symptomatic NH” implies the symptoms are secondary to an intracranial or extracranial lesion (9). Symptomatic NH has been reported in association with intracranial lesions including meningiomas, after local neurosurgery, fusiform aneurysms and arachnoid cysts, and skull lesions (9–12). Local ectodermal changes, including alopecia, hair loss and skin discolouration, have been noted in roughly 10% of patients (3,7). Hypothesised mechanisms linking to NH with local ectodermal abnormalities include neuropathy of a terminal branch of a cutaneous scalp nerve and focal nociceptive pain stemming from epicranial tissues (5,13). Infiltration of local anaesthetic has not ameliorated the pain with primary NH, but no reports describe this approach in patients with co-localised ectodermal lesions (13). Botulinum toxin type A has had moderate success (14).

Our case report contributes to the clinical phenotype of NH. The patient is the youngest in the medical literature. To our knowledge, this is the first report linking local hair heterochromia and NH. A unifying hypothesis to account for the co-localised paroxysmal headache and hair heterochromia is not obvious, although the common origin of both the hair melanosomes in the blonde patch of hair and local peripheral nerve cells in the neural crest suggests an underlying, local embryologic process.