# The Prevalence and Clinical Phenotypes of Cluster Headache in Relation with Latitude

## TL;DR

This paper explores how latitude influences the prevalence and symptoms of cluster headaches, possibly through sunlight and temperature effects.

## Contribution

The study is the first to systematically examine the effect of latitude on cluster headache phenotypes.

## Key findings

- Higher latitude is associated with increased prevalence of chronic cluster headache.
- Latitude correlates with the occurrence of miosis and/or ptosis in cluster headache patients.
- Environmental and genetic factors may also influence cluster headache manifestations.

## Abstract

Previous studies have indicated a possible link between the prevalence of cluster headache (CH) and sunlight exposure. However, this theory has yet to be tested systemically. In this article, we aim to examine how latitude affects the prevalence and phenotypes of CH.

To our knowledge, there is by far no article describing the effect of latitude on disease phenotype; thus, we performed a literature review. We noted positive effects of latitude on 1-year prevalence, the proportion of chronic CH, and the proportion of miosis and/or ptosis.

Latitude may affect the phenotypic presentations of cluster headache, probably partially mediated via temperature and sunlight variations. Still, other factors, such as environmental exposure to smoking and the genetic difference between the Eastern and Western populations, may participate in the pathogenesis and clinical manifestations of CH.

The online version contains supplementary material available at 10.1007/s11916-024-01229-3.