_____________________________________________________________________________________________________ 1 Kocaeli University, Umuttepe Campus 41350, Kocaeli, Izmit, Turkey. *Corresponding author: E-mail: buketozkara4188@hotmail.com; Chapter 9 Print ISBN: 978-93-91882-48-8, eBook ISBN: 978-93-91882-29-7 Study on Benign Episodic Unilateral B. Ozkara 1* and F. Budak 1 DOI: 10.9734/bpi/nfmmr/v9/3845F ABSTRACT Benign unilateral episodic mydriasis is a similar condition in which young individuals, mainly women, experience intermittent periods of pupillary asymmetry mydriasis. Each incident is self-contained, and no systemic or neurologic disease has been linked to the circumstance. Usually related to migraine, some authors classify it as a limited form of ophthalmoplegic migraine, although our patient have been described with no accompanying headache. She complained of anxiety, irritability and insomnia. Selective serotonin reuptake inhibitors (SSRIs) are helpful in the treatment of depression and generalised anxiety disorder, and are frequently recommended as the pharmacotheraphy of choice.The central inhibitory effects of SSRI are thought to extend to dilation linked neurons that inhibit the E.W. nucleus, therefore SSRI would suppress BUEM as well. The cause of the underlying physiopathology is unclear, however it could be parasympathetic insufficiency or sympathetic hyperactivity affecting the iris. The study objectives is the probable pathophysology of BUEM that intermittent inhibition of dilation-corelated neurons in the Edinger Westpal nucleus are responsible for the pupillary dilatations seen in BUEM. Keywords: Episodic; mydriasis; anxiety. 1. INTRODUCTION Benig unilateral episodic mydriasis is a related condition in which young individuals, primarily women, experience intermittent periods of pupillary asymmetry mydriasis. Each incident is self-contained, and there has been no link between the scenario and any systemic or neurologic disease [1,2]. Anisocorias are a relatively frequent reason for consultation in neuro- ophthalmology units. They remain a diagnostic challenge for specialists as they may be due to several aetiological factors. In the absence of other accompanying symptoms, anisocorias are usually due to benign processes [1,2]. Although it is usually associated with migraine, some authors characterise it as a limited form of ophthalmoplegic migraine, though some cases have been reported without a headache [1,2]. The underlying physiopathology is unclear, however it could be parasympathetic insufficiency or sympathetic hyperactivity that affects the iris [2,3]. We consider that intermittent inhibition of dilation-corelated neurons in the Edinger Westpal nucleus are responsible for the pupillary dilatations seen in BUEM. 2. CASE REPORT A thirty nine year old female patient presented us with intermittant enlargement in her left pupil for the last five months, explaining that this condition could last between 15-20 minutes. She has been described with no accompaying headache. Also she complained of anxiety, irritability and insomnia recently. Her neurological and physical examination was unremarkable. Her complete blood count, metabolic profile, and thyroid function test were unremarkable. She had normal head and neck magnetic resonance imaging and angiography, electroencephalography, and visual evoked potential.