HEADACHE & FACIAL PAIN SECTION Modulation of the Somatosensory Blink Reflex in the Peripersonal Space Is Defective in Episodic Migraine Selahattin Ayas, MD, PhD, Meral E. Kızıltan, MD, PhD, Feray Karaali-Savrun, MD, PhD, and Ays¸egu ¨ l Gu ¨ ndu ¨ z, MD, PhD Department of Neurology, Cerrahpasa Medical Faculty, IUC, Istanbul, Turkey Correspondence to: Ays ¸egu ¨l Gu ¨ndu ¨z, MD, PhD, Department of Neurology, Cerrahpas ¸a Medical Faculty, Istanbul University-Cerrahpasa, Complex C, Fatih, Istanbul, Turkey. Tel: 00902124143165; Fax: 00902126330176; E-mail: draysegulgunduz@yahoo.com. Funding sources: No funding. Conflicts of interest: The authors report no disclosures. Abstract Objective. In migraine, there is an altered behavior of patients during the attack and an altered connectivity in the cortical structures modulating and encoding the sensation and pain. Thus, we hypothesized that the extent of the peripersonal space (PPS) and the responses in the PPS may change during a migraine attack. For this reason, we an- alyzed the modulation of somatosensory blink reflex (SBR) in the PPS during episodic migraine. Design. Cross-sec- tional assessment of modulation of SBR in patients with migraine. Setting. Headache outpatient clinic of a tertiary re- ferral center. Subjects. We included 22 patients with episodic migraine, of whom 13 individuals were in the interictal period and nine were experiencing a headache episode. We also included 14 healthy individuals. The three groups were similar in age and gender. Methods. SBR was recorded when the participants were sitting with their forearm in the extrapersonal space and also when their hands were in the PPS surrounding the face. Latency, amplitude, and area under the curve (AUC) were measured and compared. Results. The amplitude and AUC of the SBR were signifi- cantly higher in patients during the attack compared with healthy subjects. The magnitude of the SBR was increased in the PPS in healthy subjects, whereas the increase was not significant in patients during the attack or in the interic- tal period. Conclusions. We think that the modulation in the PPS is defective in patients with migraine both during the acute attack and in the interictal phase, suggesting diminished top-down modulation of the SBR. Key Words: Somatosensory Blink Reflex; Peripersonal Space; Migraine Introduction Migraine is characterized by hypersensitivity to external stimuli during and between attacks. There is mechanical hyperalgesia in the trigeminal and extratrigeminal regions [1]. Generalized mechanical hyperalgesia has been associated with sensorimotor and psychological symptoms as well as disability [1]. As a result of common sensory hypersensitivities such as photophobia, phono- phobia, osmophobia, and allodynia, patients prefer to be alone in a silent and quiet room during the attack. They avoid being touched, specifically on the face and head. Normally, an invisible border is drawn around the per- son, and, in accordance with the social context, the distance expands or narrows under the influence of exter- nal stimuli: peripersonal space (PPS) [2]. The PPS is established and instantiated as a result of the dynamic interactions of high cognitive functions with sensory mo- dalities [3]. For example, a study in patients with trigemi- nal neuralgia revealed enhanced responses in the PPS and showed that the PPS was larger during pain [4]. Although the trigeminovascular system constitutes the cornerstone in the pathophysiology of migraine and functional neuroimaging studies have shown increased activation in the ipsilateral locus ceruleus, dorsal raphe nucleus, and periaqueductal gray matter in the ipsilat- eral dorsolateral pons [5], there are also structural or V C 2020 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com 1663 Pain Medicine, 21(8), 2020, 1663–1667 doi: 10.1093/pm/pnz328 Advance Access Publication Date: 17 January 2020 Original Research Article Downloaded from https://academic.oup.com/painmedicine/article/21/8/1663/5709920 by guest on 14 June 2022