A Strange Headache Disorder
While Migraine may be the most common headache disorder, it is certainly not the only one to produce strange symptoms. Although rare, Nummular Headache has some pretty odd symptoms, too. People affected by Nummular Headache will experience moderate to severe pain that is limited to one or more well-defined 1-6 cm round or elliptical areas on the scalp. The pain of Nummular Headache is nearly constant. Patients also report periodic spikes of intense pain in the affected locations. They don’t have any migraine-like or autonomic symptoms, just constant or near-constant pain in a small, well-defined location or locations. These painful areas may be tender to the touch, numb, or have a tingling sensation. Nummular headache occurs in the absence of skin lesions.
For example, I have a 2-inch scar on the right temporal region of my scalp that sometimes feels numb to the touch. However, it does not meet the criteria for Nummular Headache because is not 1) round or elliptical in shape) and 2) does not cause pain. Plus, the scar is a result of a skull fracture and laceration. So the numbness has a defined cause. Lucky me -- at least that's one headache disorder I can rule out!
In the March 2010 issue of Cephalalgia, a group of doctors reported using Indomethacin to successfully treat a patient with Nummular headache. Previous treatments with simple analgesics, amitriptyline, gabapentin, and dexamethasone had been unsuccessful. When a 50 mg intramuscular injection of indomethacin resulted in temporary pain relief, the patient was prescribed 25 mg of indomethacin twice daily for 2 months. At the end of that 2 months, treatment was discontinued with total remission.
Then in August 2011, another group of doctors reported positive treatment outcomes using Neurotropin® (NTP). NTP is used in Japan and China for the treatment of chronic pain. In this case, the affected patient was treated with 16 units per day for 2 months with complete remission. In their report, the physicians expressed hope that an ongoing trial of NTP by the US National Institutes of Health would yield positive results. Unfortunately, that trial was terminated early due to the small number of participants. The preliminary results were deemed inconclusive due to a small sample size.
More recently, a case study of a patient with multi-focal Nummular Headache reported remission following treatment with Gabapentin. This study also use Pressure pain Threshold testing to map out the exact location of painful areas. The results from this testing confirmed that the pain is, indeed, confined to specific round or elliptical 1-6 cm areas.
The International Classification of Headache Disorders, 3rd Edition beta version outlines the diagnostic criteria for Nummular Headache.
Previously used term: Coin-shaped headache.
Description: Pain of highly variable duration, but often chronic, in a small circumscribed area of the scalp in the absence of any underlying structural lesion.
A. Continuous or intermittent head pain fulfilling criterion B
B. Felt exclusively in an area of the scalp, with all of the following four characteristics:
1. sharply contoured
2. fixed in size and shape
3. round or elliptical
4. 1–6 cm in diameter
C. Not better accounted for by another ICHD-3 diagnosis.
Comments: The painful area may be localized in any part of the scalp, but is usually in the parietal region. Rarely, Nummular headache is bi- or multifocal, each symptomatic area retaining all the characteristics of nummular headache. Pain intensity is generally mild to moderate, but occasionally severe. Superimposed on the background pain, spontaneous or triggered exacerbations may occur. Duration is highly variable: in up to 75% of published cases, the disorder has been chronic (present for longer than 3 months), but cases have also been described with durations of seconds, minutes, hours or days. The affected area commonly shows variable combinations of hypaesthesia, dysaesthesia, paraesthesia, allodynia and/or tenderness. Other causes, in particular structural and dermatological lesions, must be excluded by history, physical examination and appropriate investigations.
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