Forensic Evaluation of a Single Episode of a Disorder of Arousal in a Sleepwalking Defense: Cognitive Function Versus Prior Clinical History

Abstract

Introduction The clinical diagnosis of disorders of arousal (DOA) is based primarily on a clinical history including amnesia for episodes. The presence of amnesia means the patient cannot provide direct evidence. In a forensic setting, when the defendant has been charged criminally with violent actions or sexual related assaults allegedly during sleep, a sleepwalking defense may be presented. As opposed to clinical history, the prosecution generally focuses on the single episode of alleged DOA that resulted in the criminal charges against the defendant. The prosecution will argue that this episode of complex behavior was not consistent with a DOA. A past history of purported episodes is not proof that a recent single episode must be a DOA. However, most sleepwalking defenses rely heavily on standard clinical evaluations despite the fact they have no direct connection with the current criminally charged episode. The International Classification of Sleep Disorders (ICSD-3) General Diagnostic Criteria C for DOAs that states "limited or no associated cognition" should be present. Recent real time studies of DOAs have shown that during DOA episodes the prefrontal cortex (PRC) is deactivated while the motor cortex remains active. Conclusion The PFC is the location of almost all executive functions including inhibition, planning, memory, and many others. Thus, when the PFC is deactivated, these higher cognitive functions are not available. The presence of higher cognitive functions during an alleged episode of DOA would be inconsistent with a deactivated PFC and thus inconsistent with generally accepted brain activity during a NREM parasomnia. This would be direct evidence that the episode could not be a DOA but occurred during wakefulness. Clinical trial No.

Keywords: Disorder of Arousal; clinical diagnosis; executive function; forensic; prefrontal cortex; sleepwalking.

Fig. 1

SPECT findings during a sleepwalking episode. In relation to data from normal volunteers during wakefulness ( n  = 24), large areas of frontal and parietal association cortices remain deactivated during sleepwalking. SPECT findings during sleepwalking after integration into the appropriate anatomical magnetic resonance image. The highest increases of regional cerebral blood flow (> 25%) during sleepwalking compared with quiet stage 3 to 4 NREM sleep are found in the anterior cerebellum – that is, in the vermis (A), and in the posterior cingulate cortex (Brodmann area 23 [Tailarach coordinate x = 4, y = 40, z = 31], B). Note the inclusion of the dorsolateral prefrontal cortex (C), the mesial frontal cortex (D), and the left angular gyrus (C) within these areas.