hemicrania continua ( hc ) is a strictly unilateral continuous headache of moderate intensity with superimposed exacerbations often accompanied by autonomic symptoms , and absolute response to indomethacin [ 13 ] . hc is an uncommon primary headache disorder , so it may be misdiagnosed and mistreated . therefore , there is a need for increasing the understanding of this entity , potentially responsive to indomethacin . we aim to analyze demographic and nosological characteristics of a series of 22 new cases of hc , including reference source and latency of diagnosis . we prospectively evaluated consecutive new patients with hc attending a headache outpatient office in a tertiary hospital over a 3-year period ( january 2008 to january 2011 ) . in every patient , we considered age at onset , sex , background pain ( side , site , type , intensity ) and exacerbation characteristics ( frequency , intensity , periodicity , autonomic symptoms ) . we assessed indomethacin response with a standard oral trial up to 250  mg per day , during 10  days . therapeutic results of patients in this series , including indomethacin side effects and alternative therapies have been considered in another article . during the inclusion period , we diagnosed 22 patients ( eight males , fourteen females ) out of 1,150 ( 1.9  % ) , who attended our headache clinic with hc . all of them fulfilled ichd-2 diagnostic criteria for hc , except the five patients without autonomic symptoms who fulfilled alternative goadsby and lipton criteria . mean age at onset was 41.8    18.1  years ( range 675 ) in all patients pain was strictly unilateral , in 14 ( 63.6  % ) right sided and in 8 ( 36.4  % ) exclusively left sided . background pain was generally rated as moderate intensity ( 5.2    1.2 ) and exacerbations were commonly considered severe ( 8.4    1.1 ) on a verbal analogical scale ( 0 : no pain , 10 : the worst imaginable pain ) . in our series , all patients suffered exacerbations and five ( 22.7  % ) of them did not have associated autonomic symptoms . all our cases responded to a standard oral trial of indomethacin , up to 250  mg per day . side effects were documented in 13 patients ( 59.1  % ) , mainly dyspepsia and dizziness . in these cases , we tried to reduce as far as possible indomethacin dose , to produce anesthetic blockade when appropriate , or to change to another preventative drug , mainly topiramate . mean latency of diagnosis was 86.1    106.5  months ( range 3360 ) . eleven patients ( 50  % ) were referred from primary care , with 9 ( 40.9  % ) coming from other neurology clinics and 2 ( 9.1  % ) from others specialities offices . hc was first designated by sjaastad and spierings   as a unilateral headache strictly responsive to indomethacin . following this description , more than 100 cases of hc have been reported in different countries . in 2004 , the second edition of international classification of headache disorders ( ichd - ii ) included hc within  other primary headache  group , and defined it as a strictly unilateral continuous headache of moderate intensity , with periodic exacerbations of variable duration and often accompanied by autonomic symptoms . bilateral or shifting - side pain localizations , or lack or enlarging of autonomic symptoms accompanying pain exacerbations can be accepted when diagnosing hc [ 5 , 9 ] but , as in other series , we have not considered non - indomethacin responders as hc , though we will consider in the future to characterize patients with non - absolute response to indomethacin . therefore , the presence of one atypical feature , such as bilateral or shifting sides localization , can be provisionally accepted provided the rest of the features are typical . hc is considered a predominantly female headache [ 5 , 7 , 10 ] and mean age at symptoms onset is around 40  years [ 5 , 7 , 11 , 12 ] . regarding demographic characteristics , our results are in line with previous reports . it was initially considered as a quite infrequent syndrome , though the increasing number of patients identified in headache offices suggested that this headache syndrome may be misdiagnosed and under recognized [ 4 , 7 , 10 ] . hc represents 1.9  % of headache patients attending our headache clinic , data comparable to those obtained by rossi et al .   and in vaga study of headache epidemiology . pain intensity in hc has been considered as mild to moderate when considering background pain , though reaching severe pain during exacerbations . according to ichd - ii criteria , patients with hc are required to have at least one cranial autonomic feature accompanying pain exacerbations , although diagnosis of hc would be possible without autonomic features when considering alternative goadsby and lipton criteria . as in other recent series , we would like to emphasize the need for a greater awareness and understanding of hc . in a similar way as described by rossi et al . , none of our patients had been diagnosed with hc and , so , they had not received indomethacin before attending our headache clinic . latency between symptoms onset and diagnosis is larger than should be expected for an entity potentially responsive to treatment , but we found it comparable to rossi et al.s results . some authors have provided data that could help clinicians be more accurate in their diagnosis . rossi et al . reported patients experience on medications in their case series  no patient who improved with triptans ended up having hc , but many of those with a partial response to nsaids or aspirin did . hemicrania continua is not an infrequent diagnosis in our headache outpatient clinic ; burden of this entity is probably higher than observed . hc is frequently misdiagnosed and there is a need for increasing the understanding of this entity , which is potentially highly disabling for patients who can achieve a pain - free state when appropriately treated with indomethacin .
hemicrania continua ( hc ) is a unilateral and continuous primary headache with superimposed exacerbations frequently associated with autonomic features . 
 diagnostic criteria of hc , according to ii edition of international classification of headache disorders require complete response to indomethacin . 
 hc is probably misdiagnosed more often than other primary headaches . 
 we aim to analyze characteristics of a series of 22 consecutive cases of hc . 
 we recruited patients from a headache outpatient clinic in a tertiary hospital over a 3-year period ( january 2008 to january 2011 ) . 
 we prospectively gathered demographic and nosological characteristics and considered referral source and delay between onset of headache and diagnosis of hc . 
 twenty - two patients ( 14 females , 8 males ) out of 1,150 , who attended the mentioned clinic during the inclusion period ( 1.9  % ) were diagnosed with hc . 
 all cases responded to indomethacin . 
 no patient received a diagnosis of hc before attending our headache office . 
 mean latency of diagnosis was 86.1    106.5  months ( range 3360 ) . 
 11 patients ( 50  % ) were referred from primary care , with 9 ( 40.9  % ) from other neurology clinics and 2 ( 9.1  % ) from other specialities offices . according to our series , 
 hc is not an infrequent diagnosis in a headache outpatient clinic . 
 diagnostic delay is comparable to data collected in previous studies . 
 as hc is frequently misdiagnosed , we thing there is a need for increasing the understanding of this entity , potentially responsive to indomethacin .