Cyclic alternating pattern (CAP) is widely recognized as an expression of sleep instability in electroencephalogram activity during non-rapid eye movement sleep. We report a case with sequences of CAP followed by bruxism and catathrenia in a 10-y-old male patient with a diagnosis of attention deficit hyperactivity disorder in treatment with methylphenidate. We found CAP in 83.1% of all episodes of catathrenia, and the CAP rate was 12.8%. We propose to consider catathrenia as one of the sleep disorders that may be accompanied by CAP.
Villafuerte-Trisolini B, Adrianzén-Álvarez F, Duque KR, Palacios-García J, Vizcarra-Escobar D. Cyclic alternating pattern associated with catathrenia and bruxism in a 10-year-old patient. J Clin Sleep Med. 2017;13(3):511–512.
Cyclic alternating pattern (CAP) is described as periodic activity in electroencephalography in non-rapid eye movement (NREM) sleep, recognized as an expression of sleep instability. It has been associated with several sleep disorders including two of the conditions in our patient; bruxism and attention deficit hyperactivity disorder (ADHD).1 Catathrenia, described as sleep-related expiratory groaning,2 has not been previously described in association with CAP. We present a case of catathrenia, bruxism, and CAP in a 10-y-old male patient.
REPORT OF CASE
A 10-y-old male presenting with bruxism and a vocal groaning sound like purring during his sleep, almost every night for the past 4 y, was scheduled for polysomnography. The child had a regular sleep schedule and no sleep complaints or daytime sleepiness. ADHD was diagnosed 5 y ago and treatment with methylphenidate started 2 y after diagnosis. He denied rhinitis, asthma, and gastroesophageal reflux. His physical and neurologic examinations were unremarkable.
A nighttime standard polysomnogram with video monitoring was performed (Figure 1). A certified sleep specialist reviewed the scoring, using version 2.3 of the American Academy of Sleep Medicine Manual for the Scoring of Sleep and Associated Events and identified CAP sequences manually, using the criteria proposed by Terzano et al.3 Total sleep time was 476.5 min, NREM sleep time; 398.5 min, rapid eye movement (REM) sleep time; 78.0 min, stage N1 1%, N2 49%, N3 34%, REM 16%, sleep efficiency 94%, wake after sleep onset 35 min, arousal index 21, apnea-hypopnea index 1.1, respiratory disturbance index 2, lowest oxygen saturation 95%; no snoring was detected.
Representative 120-sec epoch.
Channels from top to bottom are: electroencephalogram (first six channels), left eye (L EYE), right eye (R EYE), chin electromyogram (CHIN EMG), snoring microphone channel (SNORE MIC), left leg electromyogram (EMG L LEG), right leg electromyogram (EMG R LEG), EKG (electrocardiogram), cannula, thermistor, thoracic movements registry (THORAX), oxygen saturation (SpO2), capnography (ETCO2) and CO2 pressure. Horizontal headings indicate CAP phases (A, B). Length of bruxism and catathrenia are depicted in chin and microphone channels with the numbers 1 and 2, respectively.
We recognized a pattern during NREM sleep that consisted of one to two continuous, deep inspirations, preceded by or simultaneous to a type A CAP, accompanied by masticatory activity (bruxism), followed by an expiratory sound (catathrenia) and finally, a pause in respiration. The pause in respiration lasted on average two respiratory cycles. Electromyography did not show periodic leg movements. There was no evidence of epileptiform discharges.
Overall CAP rate was 12.8%, CAP rate in N1, N2, N3 was 18.8%, 27.5% 2.4%, respectively. Compared to published data,1 in our patient the A1 index was decreased (9.64 versus 39.5), whereas the A2 and A3 indices were increased (7.83 and 13.4 versus 2.7 and 3.3, respectively). There were 77 episodes of catathrenia, 83.1% of them were concomitant with CAP; 60.9% of these were phase A3, 18.8% A2, 10.9% A1, and 9.4% included phase B. All of them were associated with bruxism.
Catathrenia is a disorder described in the International Classification of Sleep Disorders, Third Edition as occurring mostly in REM sleep. To the best of our knowledge, this is the first case report of CAP occurring with catathrenia. Catathrenia has been described initially as a phenomenon occurring predominantly in REM sleep, although there have been reports of it occurring during NREM sleep.2 In our patient, these episodes occurred exclusively during NREM sleep. Groaning sounds were always preceded by inspiration, differentiating them from central sleep apnea, as previously reported.4
It is still controversial whether catathrenia exists as one single disorder or if it is part of different ones.2 Our patient has ADHD treated with methylphenidate, and in comparison to healthy age-matched controls, his CAP rate was lower (12.8% versus 33.4%).1 Likewise, the predominance of phase A3 over A1 and A2 could be due to an elevated arousal index. This could indicate a deficit of the arousal-level fluctuations. Similar findings have been described in children with ADHD, contrary to higher CAP rates reported in patients with bruxism.1 More-over, the role of methylphenidate in CAP is not fully understood and we did not find reports of ADHD related to cathatrenia. Therefore, it is possible that in our patient, the mechanisms underlying ADHD were predominant over those underlying bruxism, perhaps as the result of a specific disinhibition generated with arousal stimulation.5
CAP has been considered as a marker of sleep instability or as a modulator of adaptive responses that are absent in REM sleep and could preserve sleep continuity.6 Changes in CAP have been associated with narcolepsy, obstructive sleep apnea, ADHD, periodic limb movements, bruxism, and upper airway resistance syndrome.1 Due to the high concurrence of catathrenia and CAP sequences in our patient, we propose to consider catathrenia as one of the sleep disorders that might be accompanied by CAP.
This was not an industry supported study. The authors have indicated no financial conflicts of interest.