Elsevier

Sleep Medicine

Volume 40, December 2017, Pages 1-3
Sleep Medicine

Video-Clinical Corners
Actigraphy: a useful tool to monitor sleep-related hypermotor seizures

https://doi.org/10.1016/j.sleep.2017.09.016Get rights and content

Introduction

Sleep-related hypermotor epilepsy (SHE) is a rare form of focal epilepsy characterized by repeated episodes of vigorous hyperkinetic limb movements commonly confined to sleep. Seizures are highly stereotyped within patients and usually last less than two minutes [1]. Wrist-actigraphy is commonly used to estimate the sleep-waking rhythm [2]. Limb accelerometer sensors have been occasionally used for the detection of epileptic events during sleep [3], [4], [5], [6], but routine wrist-actigraphy has not been described in SHE.

We herein report a case of SHE monitoring with wrist-actigraphy, and a concomitant video-polysomnography (v-PSG) during the last night of the actigraphic recording that successfully detected the hypermotor seizures. Written informed consent was obtained from the patient to show his data and video image.

A 51 year-old man was referred to our sleep center because of SHE since childhood. The episodes of SHE occurred several times per night, lasted for 1–2 min, and consisted in kicking and limb shaking with dystonic postures, often associating vocalizations. He did not refer snoring, restless legs or other sleep-related symptoms. The patient denied family history of epilepsy. Ancillary tests such as neuroimaging and cognitive assessment were normal. Since he worked in shifts, in order to assess his sleep/wake pattern, we performed a three-week actigraphy of the non-dominant hand, with simultaneous v-PSG during the last night of actigraphic recording (Fig. 1). For the v-PSG, a 21-channel montage was used for the electroencephalographic (EEG) recording. The patient was on 1200 mg a day of eslicarbazepine acetate at the time the investigations were done.

A three-week actigraphy (Fig. 1) revealed 2–15 short episodes of increased motor activity per night (except from one night free of events) that were presumably related to seizures. As calculated from the actigraphic recording, a total of 180 seizures were detected, with a mean duration of 2 min and 6 s (94 seizures lasted approximately two minutes, 42 three minutes, 38 one minute and 6 lasted four or five minutes).

A detailed view of the wrist-actigraphy, the night of the simultaneous v-PSG (red arrow), showed 13 events of increased movement signal (Fig. 1) that corresponded to the SHE episodes. The first seizure appeared 58 min after sleep onset. All the epileptic events occurred during NREM sleep, the first 3 in stage N3 and the following 10 in N2 stage. Seizures were highly stereotyped and characterized by an initial dystonic posture in the limbs and then hyperkinetic movements involving the four extremities and the whole body, always with eyes open (Video). In eight of the events, the patient talked and answered coherently at the end of the episodes. A nearly simultaneous arousal was recorded in 3 episodes and, in the remaining 10, the EEG recording showed an arousal 4–7 s before the motor activity started. The seizures lasted for 1–2 min, with a mean duration of 1 min and 23 s. After each seizure, the patient would rapidly fall asleep. Epileptiform activity was not seen on the EEG recording, neither intercritically nor during the episodes. Three periods of REM sleep were recorded, all without hypermotor seizures.

The following is the supplementary data related to this article:

. During one of the v-PSG recorded seizures (*) the patient displays a dorsal flexion of the right foot, dystonic posture of the right leg, followed by bilateral kicking and violent, shaking movements of the four limbs. At the end of the episode the patient talks coherently.2

The seizures were seen as EMG/movement artifact in the digital spectral array (Fig. 1). Also, the hypnogram demonstrated that seizures only occurred during NREM sleep and induced awakenings (Fig. 1, arrow heads in D).

Additionally, the v-PSG showed a discrete number of periodic limb movements during sleep (index of 16.6 per hour) in the first half of the night that exclusively involved the lower limbs and were clinically discernible from the seizures. No other sleep disorders were identified.

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Discussion

The diagnosis of SHE is based on established criteria, including clinical, video and video-EEG recordings [1]. In our patient, the presence of several typical events during the video-PSG recording led to a diagnosis of Video-documented (clinical) SHE. Our case illustrates that, in SHE patients that are already diagnosed, actigraphic recordings may be useful to monitor the frequency of seizures. The concomitant actigraphic and v-PSG recording in our patient, allowed us to correlate the epileptic

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These authors contributed equally to the manuscript.

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