Abstract
To the Editor:
I read with great interest the manuscript by Douglas and colleagues about “Orbital myositis triggering oxygen-responsive cluster headache” (1), drawing attention to orbital myositis (OM) as being the initial manifestation of cluster headache.
McNab recently proposed a new classification system that might serve as a basis for a clearer understanding of OM and also as a framework for future research into this extremely rare report. Approaching in a mild and didactic way the classification of OM and its main causes, the author facilitates a practical approach to the knowledge of the subject for both the specialist and the novice physician (2).
OM is classified as an orbital inflammatory disease and is defined by inflammation of the extraocular muscles. OM was considered a subgroup of orbital pseudotumor syndrome, in which one or more of the extraocular muscles are primarily infiltrated by an inflammatory process (3). The major differential diagnosis is thyroid ophthalmopathy. However, dysthyroid myopathy is usually painless in onset, symmetrical, slowly progressive, and associated with systemic manifestations of Grave’s disease. OM bears many similarities to uveitis. It is an inflammatory condition, often idiopathic, but also often occurring in the setting of specific autoimmune, inflammatory, and infective conditions. The role of the image is fundamental for the diagnosis of OM (2).
As a single suggestion, and with the patient having possible trigeminal nerve involvement, I would like the authors to have complemented the assessment with a neurophysiological study with the blink reflex or evoked potential related to pain.
I congratulate the authors for the report of the first description of a case of a secondary trigeminal autonomic cephalalgia from orbital myositis responsive to high-flow oxygen and the opportunity to delve into a topic so interesting that it will serve as a motivation for further studies.
Footnotes
Declaration of conflicting interests
The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author received no financial support for the research, authorship, and/or publication of this article.