Nummular headache: Clinico-epidemiological features in South Indian population

Context: Nummular headache (NH) is a primary disorder characterized by head pain exclusively felt in a small-rounded area typically 2-6 cm in diameter. Aims: The aim of this review is to study the clinical and epidemiological features of NH in a patient population of South India and to compare this with that of described in the international literature. Settings and Design: A prospective, observational study conducted in a tertiary care center. Materials and Methods: Patients attending the medicine and neurology outpatient departments of a tertiary referral hospital in South India diagnosed to have NH as per the International Classification of Headache Disorders 3 beta (2013) criteria were studied over 30 months. All of the patients had a normal neurological examination. Neuroimaging findings were normal, except in one patient. Results: A total of 19 females and 10 males were studied. The mean age of onset was 47.62 years (range 36-60). The duration of headache varied from a minimum of 3 months to a maximum of 5 years, with a mean of 24.17 months. The site of headache was predominantly in the parietal area 15 (51.72%), followed by the occipital area 7 (24.13%). The mean diameter of the affected area was 3.23 cm. The intensity of the headache proved to be mild to moderate with a mean visual analog scale score of 5.03. The quality of pain was mainly felt as burning dysesthesia 12 (41.38%). In the majority of patients, i.e. 21 (72.41%), pain was chronic and continuous. None of the patients had any significant trophic change even though paresthesias, dysesthesias, and allodynia were reported by a significant minority of patients, i.e. 9 (31.03%). Only one (3.45%) patient gave a history of head injury. Ten (34.48%) out of 29 patients had other types of concurrent headaches; the majority of which proved to be migrainous, i.e. 7 (24.14%), 2 patients (6.89%) with tension headache, and 1 patient (3.45%) with trigeminal neuralgia. Conclusion: Our study proves the existence of the newly described primary headache syndrome called NH in South Indian population. In comparing our results with the international literature, the number of similarities is much greater than the differences. The etiology of pain in our series appeared to be primarily peripheral with a role for central pain sensitization in some cases due to a variety of concurrent central causes of head pain.