An Elderly Man With Chaotic Sleep Behaviors and Rapidly Progressive Ataxia

Sleep disorders are increasingly recognized as common features of autoimmune encephalitis (AE), manifesting in various presentations, including insomnia, hypersomnia, rapid eye movement sleep behavior disorder (RBD), non-rapid eye movement (REM) parasomnias, and sleep breathing disorders. These features may be overlooked because of the difficulty of detecting them and a lack of awareness of their significance. Here, we provide an interesting case, with video-polysomnography (v-PSG) documentation, of an unusual sleep manifestation associated with rapidly progressive ataxia of an elderly man with AE. An 87-year-old man, who was a retired soldier with previously able activity of daily living is activity of daily living, presented with progressive hypersomnolence and abnormal behaviors during sleep over the last 3 months. His wife observed that he occasionally had abnormal motor behaviors during sleep, resembling fighting in the air during the night. In the last 2 months, he also had visual hallucinations and his cognition had declined. One week before admission, he developed an unsteady gait with repeated falls and the abnormal motor behaviors during sleep occurred more frequently. His past medical history included well-controlled type 2 diabetes mellitus. Current medications were linagliptin (5 mg/day) and repaglinide (150 mg/day). He had no history of illicit drug or alcohol use. On admission, general examinations were unremarkable. However, although he was alert and co-operative, he intermittently lapsed into sleep, but was easily roused. During those sleep episodes, he developed abnormal behaviors resembling daytime work tasks and vocalizations (mumbling sound), which immediately presented from the onset of sleep (Video 1). These abnormal sleep episodes occurred most of the day and night time. Eye movement examination revealed broken pursuit and hypermetric saccades, whereas other cerebellar signs were impaired, consisting of truncal ataxia, wide-based gait, impaired tandem gait, and impaired bilateral finger-to-nose test (Video 2). Montreal Cognitive Assessment score was 14/30 with the prominent impairment of attention and recall memory. Other examinations were normal. After a few days after admission, his symptoms rapidly progressed. His consciousness declined to stupor with frequent inspiratory stridor, requiring intubation and ventilator support. We did not observe any episode of faciobrachial dystonic seizures (FBDS) during admission. This video was performed on the second night of admission. He developed abnormal behaviors resembling doing daytime work tasks and vocalization (mumbling sound), which immediately presented from sleep onset. Video content can be viewed at https://onlinelibrary.wiley.com/doi/10.1002/mdc3.13537 Eye movement examination revealed broken pursuit and hypermetric saccades, whereas other cerebellar signs were impaired, consisting of truncal ataxia, wide-based gait, impaired tandem gait, and impaired bilateral finger-to-nose test. Video content can be viewed at https://onlinelibrary.wiley.com/doi/10.1002/mdc3.13537 Blood chemistry revealed marked hypokalemia (2.2 mmol/L) without hyponatraemia (Na 138 mmol/L). Cerebrospinal fluid (CSF) profiles revealed white blood cell (WBC) 3 cell/mm3, no red blood cell (RBC), protein 27 mg/dL, glucose 75 mg/dL. Magnetic resonance imaging (MRI) brain scan showed no abnormal hypersignal intensity or contrast enhancement, whereas electroencephalography demonstrated diffuse background slowing without epileptiform discharge. Interestingly, the 24 hours wearable v-PSG test exhibited at almost every time period a mixture of α rhythm, REM, and slow-wave sleep, which was compatible with status dissociatus (SD) (Fig. 1). The serum autoimmune and paraneoplastic antibodies were positive for leucine-rich glioma-inactivated 1 (LGI1) antibody, whereas the rest (NMDAR, CASPR2, GABAb, DPPX6, AMPA, Ma2, IgLON5) were all negative, but anti-LGI1 and other antibodies were negative in CSF studies. Comprehensive radiological investigations, consisting of computed tomography (CT) chest and whole abdomen did not identify any underlying malignancy. A complete course of intravenous immunoglobulin and pulse methylprednisolone was given, followed by oral prednisolone, which gradually improved cognition and reduced abnormal sleep episodes. He could walk without support 3 months later and abnormal sleep episodes were gone. The presentations of our patient, consisting of rapidly progressive cerebellar ataxia, cognitive impairment, and subacute sleep–wake disorders including progressive hypersomnolence and abnormal behaviors during sleep, raised the possibility of an autoimmune process, prion disease, or an atypical presentation of a neurodegenerative disease, such as dementia with Lewy bodies. The presence of SD was a unique characteristic in this case. SD is an extreme form of parasomnia with overlapping features of non-REM, REM sleep, and wakefulness and is presented in fatal familial insomnia1 or severe alcohol withdrawal syndrome.2 In addition, the combination of sleep disturbances, inspiratory stridor, and gait instability could lead to the possibility of encephalopathy associated with IgLON5 antibodies.3 However, our case had other atypical presentations, including progressive cerebellar ataxia, lack of FBDS, and lack of hyponatraemia. The typical presentation of anti-LGI1 encephalitis, which is frequently manifested in elderly men,4-6 is characterized by a triad of memory changes, seizures, and abnormal movements. FBDS has been reported in 26% to 71% of patients with anti-LGI1 encephalitis.4 Finally, although sleep disorders in AE are less recognized in clinical practice, these features have been reported in 20% to 65% of patients with anti-LGI1 encephalitis, encompassing insomnia, hypersomnia, RBD, periodic limb movements in sleep, and obstructive sleep apnea.7-9 In addition, we reviewed relevant literature on sleep disorders and AE, as shown in Table 1. Considering cerebellar ataxia in anti-LGI1 encephalitis, only two case reports were identified of a child and a young adult with LGI1 antibody-associated AE presented with progressive and episodic ataxia.10, 11 In conclusion, we would like to emphasize the importance of sleep disorders in AE. Sleep disorders can be the first clinical presentation in AE, a treatable disorder, and v-PSG can assist in differentiating sleep disturbances to aid diagnosis. Early awareness and prompt effective management of uncommon sleep manifestations are vital and potentially associated with improved treatment outcomes (Video 3). Full video from the 2021 Video Challenge. Video content can be viewed at https://onlinelibrary.wiley.com/doi/10.1002/mdc3.13537 (1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique. T.P.: 3A W.P.: 3A R.B.: 3B J.S.: 3B The authors confirm that the ethics board clearance was not required for this work. The subject has provided written video consent. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. No specific funding was received for this work, and the authors declare no conflicts of interest relevant to this work. Author RB has received a salary from Chulalongkorn University and a stipend from the Royal Society of Thailand; he has also received consultancy and/or honoraria/lecture fees from Abbott, Boehringer-Ingelheim, Britannia, Ipsen, Novartis, Teva-Lundbeck, Takeda, and Otsuka pharmaceuticals. He has received research funding from the Thailand Science and Research Innovation Bureau, Thailand Research Fund, Crown Property Bureau, Chulalongkorn University, and the National Science and Technology Development Agency. He holds patents for laser-guided walking stick, portable tremor device, nocturnal monitoring, and electronic Parkinson's disease symptom diary, as well as copyright on Parkinson's mascot, dopamine lyrics, and teaching video clips for common nocturnal and gastrointestinal symptoms for Parkinson's disease. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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