Association of Idiopathic Rapid Eye Movement Sleep Behavior Disorder in an Adult with Persistent, Childhood Onset Rhythmic Movement Disorder

Abstract

We present a case of a 41-year-old man with the association of REM sleep behavior disorder (RBD) and rhythmic movement disorder (RMD). The RMD had a childhood onset and persisted into adulthood. The RMD worsened with the development of RBD and has persisted despite successful treatment of RBD. However, the pathogenesis of RMD remains unclear and the movements have been suggested to play a maturational role as part of psychomotor development by stimulating the vestibular apparatus. Current models underlying the control of REM sleep may need to be refined to explain the observed association of RBD and RMD.

Citation:

Xu Z; Anderson KN; Shneerson JM. Association of idiopathic rapid eye movement sleep behavior disorder in an adult with persistent, childhood onset rhythmic movement disorder. J Clin Sleep Med 2009;5(4):374-375.

The association of RMD with RBD is novel. RMD is characterized by repetitive, rhythmic motor behaviors that occur predominantly at sleep onset. RMD is common in normal infants but persists into adulthood in less than 5% of cases.¹ In contrast, RBD is a late onset parasomnia characterized by the presence of REM sleep without atonia leading to dream enactment. We report an adult patient who had childhood-onset RMD that persisted into adult life and then developed typical RBD.

REPORT OF CASE

A 41-year-old-man presented to us with an gradually worsening 10-year history of sleep disturbance. He complained of intrusive dreams in which he was attacked; he had enacted them with self-injury. He also had a separate complaint of rhythmic leg kicking, present since childhood, that predominantly occurred on falling asleep. These movements had worsened with the onset of the new sleep disturbance.

He was diagnosed with depression 5 years before and treated with citalopram. Neither the onset of depression nor treatment had any effect on his sleep disturbance or movements. He had smoked 1 cigarette/day, rarely drank alcohol, and took 5 caffeinated drinks daily. He had a twin brother who also had RMD, consisting of body rocking during his childhood, but with no sleep difficulties in adulthood.

The patient had a body mass index of 31.3 kg/m² and a normal neurological examination. He scored 8/24 on the Epworth Sleepiness Scale. A sleep diary showed that he went to bed between 22:30 and 00:00 with frequent awakenings before waking for the day at 08:30. Both rhythmic movements and dream enactment occurred nightly.

Standard laboratory video polysomnography revealed prominent rhythmic movements (see diagram). These occurred at a frequency of 0.73 Hz and involved the large muscle groups in both the legs and trunk. A total of 1010 rhythmic limb movements were recorded. These were most prominent at the transition from wakefulness to stage 1 sleep and stage 1 sleep to wakefulness but were present in all sleep stages and were often preceded by high-voltage K complexes. Periodic limb movements typical of restless legs syndrome were absent.

The limited sleep EEG montage did not demonstrate epileptiform activity. The arousal index was 67.8/hr in NREM sleep and 109.3/hr in REM sleep. The apnea/ hypopnea index was normal at 4.4.

This study also demonstrated sustained loss of muscle atonia during REM sleep, during which episodes of punching and kicking were observed. The findings were typical of RBD.

Further investigations included a magnetic resonance imaging scan of the brain (which was normal) and a lumbar puncture to measure cerebrospinal fluid levels of orexin (253 pmol/L). A score of 30/40 was obtained on the University of Pennsylvania Smell Identification Test (normal > 34). He was followed over 18 months: The RBD responded well to zopiclone (following a failed trial of clonazepam), with reduction in aggressive dream frequency and intensity. RMD persisted despite a trial of gabapentin, and continues to prevent him from sleeping with his partner.

DISCUSSION

We present a patient with a persistent, childhood-onset RMD worsening with the development of RBD. The observed association of RMD with RBD could be coincidental. RMD-like movements occurring in the context of RBD episodes have previously been described in 2 patients with idiopathic RBD without a personal or family history of RMD.² However, these movements were infrequent, with only 2 bouts of movements recorded during REM sleep in one patient, and 1 bout of movement recorded during an episode of RBD. In our patient, a total of 1010 movements were recorded during all sleep stages and were present before RBD episodes. This is likely to represent a distinct phenomenon.

Figure 1.

Hypnogram showing sleep architecture and limb movement recorded during polysomnography. Waking (W), Stages 1, 2, 3, 4, and REM sleep, movement (MT), and limb movements are shown on the y axis, and time on the x-axis. A highly disrupted sleep architecture with poor consolidation of the deeper stages of NREM sleep is seen along with rhythmic limb movements found mainly at the transitions from wakefulness to stage 1 sleep and stage 1 sleep to wakefulness (although present during all sleep stages). The arrows indicate the occurrence of RBD movements: punching, kicking, and muscular twitches were observed.

In RMD, movements may occur during REM sleep, NREM sleep, or both.³ In a series of patients with RMD persisting beyond infancy, some of the rhythmic movements occurring during REM sleep were observed to be preceded and followed by loss of muscle atonia in a subset of patients.⁴ Patients in this series were younger than 25 years old, and it would be interesting to know if these patients subsequently developed RBD in later life. Loss of muscle atonia may underlie the association of RMD and RBD but will require further confirmation.

RMD occurring exclusively during REM sleep has been suggested to be a variant of RBD.⁵ However, the near-complete resolution of RBD in our patient without a parallel improvement in the RMD suggests that the relationship between these 2 distinct parasomnias is more complex.

This case highlights the need for in-laboratory video polysomnography in patients with parasomnia to correctly identify the cause of movements that disturb sleep.

DISCLOSURE STATEMENT

This was not an industry supported study. The authors have indicated no financial conflicts of interest.