Bath-related headache induced by varenicline

Cefaleia relacionada ao banho induzida pela vareniclina

OPINION

Bath-related headache induced by varenicline

Cefaleia relacionada ao banho induzida pela vareniclina

Marcelo Moraes Valença

Departament of Neuropsychiatry, Universidade Federal de Pernambuco (UFPE), Recife PE, Brazil

^{Correspondence}

Dear Editors,

The article by Camara Filho et al.¹ reports the case of a woman with recurrent headache attacks which occurred after the use of varenicline. The usual presentation of bath-related headache is a recurrent sudden severe headache attack (i.e. thunderclap headache) typically triggered by bathing or other activities involving body contact with water². The authors commented the possibility of reversible cerebral vasoconstriction as a cause of bath-related headache¹. Interestingly, two cases of thunderclap headache have recently been reported³ associating reversible segmental vasoconstriction with the use of varenicline. The alpha4beta2 nicotinic receptor partial agonist varenicline is a drug authorized for promoting smoking cessation in the USA and Europe. This receptor mediates the primary effects of nicotine on the mesolimbic system, activating the dopaminergic reward pathway. Thus, by acting as a nicotinic antagonist, it inhibits dopamine release, thereby decreasing the effects of smoking satisfaction often associated with nicotine use. It was developed from cytisine, a natural alkaloid compound widely used to increase the chances of a person successfully giving up smoking. Cytisine is found in the Baptisia, Cytisus, Laburnum, and Sophora species, and has nicotine-like effects on the nervous system. These plants may have a recreational purpose when used for smoking because of their stimulant effects and mild hallucinogenic properties. The Sophora root, also known as "Ku Shen", is used in traditional Chinese medicine. The use of such plants by humans, for whatever purpose, may suggest that a particular alimentary/recreational habit might be the reason for a higher prevalence of bath-related headache among Asian populations. Curiously, the usual trigger is hot water, suggesting an imbalance in the thermogenic CNS circuitry. Pharmacological stimulation of α4β2 nicotinic receptors causes changes in body temperature. Indeed, varenicline is able to experimentally modulate hypothermia and antinociception induced by nicotine. This may explain the higher susceptibility (i.e. dysfunctions in craniofacial somatosensory processing) to hot water in contact with the head when someone is undergoing treatment with varenicline. Similar phenomenon occurs in a unique form of reflex epilepsy, i.e. hot water epilepsy⁴. Ravishankar reported⁵ that migraine attacks were triggered by hair washing in 94 people in a series of 1,500 Indian migraineurs. Some adverse effects may occur soon after the intake of varenicline, and others developed after several weeks of treatment or even after stopping varenicline. Due to the increasing use of smoking cessation drugs, this fascinating form of headache may be more frequent than generally believed.

Received 15 June 2012

Accepted 22 June 2012

Conflict of interest: There is no conflict of interest to declare.

• 1. Camara Filho JW, Medeiros FL, Sougey EB. Bath-related headache: a Brazilian case report. Arq Neuropsiquiatr 2012;70:383-384.
• 2. Mak W, Tsang KL, Tsoi TH, et al. Bath-related headache. Cephalalgia 2005;25:191-198.
• 3. Geevasinga N, Mahant N, Fung V. Call-Fleming syndrome associated with Varenicline. Australian and New Zealand Association of Neurologists Annual Scientific Meeting, 1619 May 2011. Available at: http://www.anzan2011.com/abstract/62.asp [cited 8/18/2011]
• 4. Bebek N, Gürses C, Gokyigit A, Baykan B, Ozkara C, Dervent A. Hot water epilepsy: clinical and electrophysiologic findings based on 21 cases. Epilepsia 2001;42:1180-1184.
• 5. Ravishankar K. 'Hair wash' or 'head bath' triggering migraine - observations in 94 Indian patients. Cephalalgia 2006;26:1330-1334.

Publication Dates

• Publication in this collection
  14 Nov 2012
• Date of issue
  Nov 2012