Nummular headache: coin-shaped scalp pain, causes and treatment

The word nummular comes from the Latin for coin. A case report describes the diagnostic criteria in the second edition of the International Classification of Headache Disorders as a consistent rounded or elliptical area of pain, typically 2 to 6 cm in diameter, that is chronic and either continuous or interrupted by spontaneous remissions lasting weeks to months. A consistent location, usually in the parietal region (the upper side of the head), lancinating exacerbations and a delineated boundary of the painful area are other characteristic features.

A Spanish observational study of 183 patients describes the typical phenotype as a parietal circular pain of about four centimetres in diameter, moderate in intensity and oppressive in quality. It is classified as a primary headache disorder, in the group of other primary headache disorders, which means there is usually no underlying structural cause. The cause of the pain is not fully understood; case reports discuss whether it arises from nerves in the scalp or from a central mechanism.

The NHS does not have a page on nummular headache, and no UK patient leaflet was available when this page was prepared. The condition-specific information below comes from published case reports and a cohort study, and the NHS headache page is used for general headache safety advice.

A case report of a 54-year-old woman illustrates a typical picture: mild to moderate pain that was lancinating or electric in quality, located at the vertex and one side, circular in shape, about 3 cm across, with a clear-cut boundary from the surrounding non-painful scalp. It peaked and subsided spontaneously, there was no aura or associated symptoms such as nausea, and pain was intensified when she combed her hair or touched the painful area.

The same report notes that allodynia (pain to light touch) and hyperaesthesia (increased sensitivity) within the painful area can occur, and that focal changes in the skin, such as trophic change, are infrequently found. Pain can be continuous or come in bouts, and some people have remissions of weeks or months.

The NHS says most headaches go away on their own and are not a sign of something more serious. It advises seeing a GP if you have tried treating a headache yourself and it is not getting better or is getting worse, or if you regularly get headaches. Because nummular headache is persistent and fixed in one spot, it is a reason to see a GP rather than to keep self-treating.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have a headache with vision or eye problems, a headache triggered or made worse by coughing, sneezing, bending or exercise, a headache with being sick, or a headache with jaw pain when eating or a sore or tender scalp. It says to call 999 or go to A&E if a headache started suddenly and is extremely painful, follows a head injury in the last 3 months, comes with a seizure, numbness or weakness, difficulty speaking, balancing, walking or remembering things, drowsiness or confusion, loss of vision, a non-fading rash, or a very high temperature, stiff neck or bright lights bothering you.

A tender scalp together with jaw pain on eating is a recognised sign of temporal arteritis, which needs urgent assessment and should not be assumed to be nummular headache.

Diagnosis is clinical. A doctor takes a history, examines the scalp and the nervous system and checks that the pain fits the criteria and is not better explained by another condition. The cohort study required a diagnosis according to the ICHD-3 criteria and excluded people with a secondary cause, including post-traumatic nummular headache.

A case report describes a woman with typical nummular headache whose MRI revealed a pituitary tumour, and whose pain subsided after surgery to remove it. The authors reviewed a few other reports linking nummular headache to structural changes in the head. This does not mean such causes are common; it is the reason why atypical features, new neurological symptoms or a change in pattern should prompt further assessment.

The NUMITOR study notes that there are no randomised controlled trials, so treatment recommendations are based on case reports, case series and retrospective cohorts, and propose gabapentin as first-line therapy and onabotulinumtoxinA for treatment-resistant patients. It states that preventive treatment is required by 50 to 80% of patients.

In its 183 patients, the highest responder rates were for onabotulinumtoxinA (62.5% had at least a 50% reduction and 47.5% at least a 75% reduction), followed by gabapentin (43.7% and 35.2%). Oral preventive drugs were not tolerated by 12.9 to 25% of patients. The authors conclude that onabotulinumtoxinA was the most effective and best-tolerated drug, but describe the evidence as class IV, meaning low-level.

The NHS suggests for headaches in general that you drink plenty of water, rest, try to relax, take paracetamol or ibuprofen, and that a headache diary may help you work out triggers. Prescription treatment is decided by a GP or neurologist, and botulinum toxin injection is a specialist procedure.

The sources describe nummular headache as a chronic condition that may be continuous or have spontaneous remissions, so outcomes vary. A pain diary showing the exact location, how long it lasts and what makes it better or worse helps a clinician decide whether a primary headache disorder is likely and which treatment is worth trying.