"Hemicrania continua should not be classified as a trigeminal
autonomic cephalagia."

Source.
Department of neurology, Brigham and women's hospital,
Harvard medical school, Boston MA, USA.

Abstract.
BACKGROUND: The pain of the so-called functional or primary
headache disorders, such as tension headaches, migraine,
or cluster headaches, can be associated with autonomic
symptons that are localized in nature. the localized
autonomic symptons proberly involve higher centers
autonomic regulation, for example the hypothalamus,
for which there is support from funcional magnetic
resonance imaging studies.

METHOD: Hermicrania continua,a continuous, unilateral,
side-locked headache,absolutely responsive to preventive
treatment with indomethacin, is contrasted with so-called
medication-overuse headache, in which the paradoxical
situation exists of tremendous suffering despite excessive
use of abortive medications.

CONCLUSION: In classification, clinical presention trumps
experimental testing. Not only is there no basis to classify
hemicrania continua in the category of the so-called
trigeminal autonomic cephalagia  also the existance of
this category lacks solid foundation.

Hemicrania continua should UNQUESTIONABLY be classified
as a trigeminal autonomic cephalagia.

Source.
Universidade federal do Rio De Janerio, Brazil.

Abstract.
Hemicrania continua (HC) is  a well-known primary headache
The present version of the international classification of
headache disorders lists (HC) in the "other primary headache
group". however, evidence has emerged demonstrating
that (HC)  is a phenotype that belongs to the trigeminal
autonomic cephalagias together with cluster headaches
paroxysmal hemicrania (PH), and short-lasting unilateral
neuralgiform headache attacks with conjunctival
injection and tearing.this is supported by a  common
general clinical picture paroxysmal unilateral, side-locked
headaches located to the ocular frontal, and/or temporal
regions, accompanied by ipsilateral autonomic disfunctions
including for example, tearing and conjunctional
injenction. Apart from the remarkable clinical similarities,
the absolute and incomparable effect of indomethacin in (HC) parallels the effect of this drug in (PH), suggesting
a shared core pathogenesis. finally, neuroimage findings
demostrate a posterior hypothalamic activation in (HC)
similary to cluster headaches. (PH), and short lasting,
unilateral neuralgiform headache attacks with conjunctival
injection and tearing. Taken together, data indicate that
(HC) is certainly a type of trigeminal autonomic cephalagia
that should no longer be placed in a group of miscellaneous
primary headache disorders.


Does this mean we are getting closer to an answer,
headaches that mimic cluster headaches, or is the
jury still out?

The attachment contains the entire article. The abstract may help with your answer.

Article abstract—Background: Hemicrania continua is an indomethacin-responsive headache disorder characterized by
a continuous, moderate to severe, unilateral headache. More than 90 cases of hemicrania continua have been reported, but there is still uncertainty about its clinical features.

Methods: The authors compared 34 new cases (24 women, 10 men)
with previously reported cases. All the patients met Goadsby and Lipton’s proposed criteria. The authors compared baseline (continuous background headache) and exacerbation (attacks of severe periods of headaches).

Results: The baseline headache was typically mild to moderate in intensity and usually not associated with severe disability. In contrast, the headache exacerbations were severe and associated with photophobia, phonophobia, nausea, and disability.

At least one autonomic symptom was present in 25 patients (74%). Jabs and jolts were present in 14 patients (41%). The mean indomethacin dose was 136.7 60 mg (range 25 to 225 mg). Twenty-four patients (70.6%) met International
Headache Society criteria for migraine in their exacerbation period. Occipital tenderness was observed in 23 patients
(67.6%). The temporal pattern was remitting in four patients (11.8%), continuous from onset in 18 (52.9%), and continuous evolving from remitting in 12 (35.3%).

Conclusion: Hemicrania continua is not a rare disorder. All cases of chronic unilateral daily headaches should receive an indomethacin trial early if not first in treatment.
NEUROLOGY 2001;57:948–951

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Thanks for that info.

Hoppy