There have been previous reports of abnormal nocturnal behavior due to hypoglycemia. Yang et al reported the case of a 79-year-old woman who was diagnosed with type 2 diabetes and was admitted for abnormal nocturnal behavior manifesting as leg shaking, fumbling with bedclothes, crawling around the room with her eyes closed, and nonresponsiveness to verbal communication due to hypoglycemia. EEG and PSG investigations showed no epileptic activity. Suzuki et al reported the case of a 65-year-old man with insulinoma who initially developed stereotypical behaviors and then progressed to more complex behaviors occurring early in the morning such as sudden laughing, clapping of hands, and crossing one leg over the other in an odd and strange manner. Laboratory studies revealed hypoglycemia with a fasting blood glucose of 0.83 mmol/L (15 mg/dL). Another case reported by Lysenko et al involved a patient with type 2 diabetes diagnosed with hypoglycemia and obstructive sleep apnea (OSA). Her medication regimen consisted of 28 IU of insulin glargine once a day, 500 mg of metformin twice a day, and 4 mg of glimepiride before breakfast and 2 mg before dinner. She was seen ripping things off the ceiling and walls, such as blinds, pictures, light bulbs, and fixtures, and destroying the TV, among other erratic behaviors. The serum glucose level was 1.94 mmol/L (35 mg/dL) at that time. After adjusting her medication dosage to 14 IU of insulin glargine once a day, 500 mg of metformin twice a day, and 4 mg of glimepiride before breakfast, no additional episodes occurred during 1-year follow-up.
These cases demonstrate that hypoglycemia is one of the most important causes of abnormal nocturnal behavior. The present case was initially misdiagnosed as nighttime epilepsy or a sleep disorder, such as sleepwalking or REM sleep behavior disorder.
Abnormal nocturnal behavior can be caused by various conditions, including primary sleep disorder, nocturnal seizures, and underlying medical or neurological disorders. These can be differentiated by the clinical presentation, associated medical conditions, and PSG with extended EEG.
Autosomal dominant nocturnal frontal lobe epilepsy (ANDFLE) is an epileptic disorder that causes frequent violent seizures during sleep. These seizures often involve complex motor movements, such as hand clenching, arm raising or lowering, and knee bending. Vocalizations, such as shouting, moaning, or crying, are also common. A diagnosis of nightmares, night terrors, parasomnias, or various other psychiatric disorders is often initially incorrectly made. EEG and PSG may show epileptic discharge in unilateral or bilateral frontal, frontal-central, frontal-temporal, or temporal area, or an increase in slow waves. ANDFLE usually occurs during NREM II sleep stage. This patient did not display typical manifestations of ANDFLE. In addition, the PSG did not show any abnormalities during NREM II sleep stage.
Sleepwalking usually occurs during the ages of 4 to 8 years. Sleepwalking episodes typically begin as confusional arousal. They can also begin with the individual immediately leaving the bed and walking or even “bolting” from the bed and running. The sleepwalking individual is disoriented in terms of both time and place, with slow speech, severely diminished mentation, and blunted responses to questions or requests. Almost all of the episodes occur during the NREM 3 sleep stage. The PSG shows high amplitude slow waves during the NREM 3 sleep stage. However, our patient did not manifest with these abnormalities.
RBD is characterized by abnormal behaviors emerging during REM sleep that may cause injury or sleep disruption. RBD is also associated with EMG abnormalities during REM sleep. The EMG demonstrates an excess of muscle tone during REM sleep, and/or an excess of phasic EMG twitch activity during REM sleep. However, the REM sleep stage of this patient was normal.
In summary, palpitations, dizziness, and cold sweats are common manifestations of hypoglycemia. Some other symptoms such as mental disorder or abnormal behavior are atypical, which may lead to a misdiagnosis of epilepsy, infarction, or mental disorder, among others. For physicians, if the cause of abnormal behavior cannot be detected, hypoglycemia should be suspected. Long-term persistent hypoglycemia may cause brain dysfunction and even result in permanent brain damage. This study has a limitation. As nocturnal mental disorders caused by hypoglycemia are not common, we have only studied 1 case and cannot comprehensively summarize the common characteristics of this kind of disease. Therefore, we look forward to further studies with a larger sample size in the future.
The authors wish to express their gratitude to the reviewers for their critical comments. The authors thank Dr Yang Feng for his help in the processing of manuscript picture format.
Conceptualization: Ning Weng, Wen Yan Luo, Yue Zhang.
Data curation: Ning Weng.
Investigation: Ning Weng, Wen Yan Luo, Dong Jian Xu.
Methodology: Ning Weng.
Project administration: Ning Weng, Yue Zhang.
Resources: Yue Zhang.
Writing – original draft: Ning Weng.
Writing – review & editing: Ning Weng, Wen Yan Luo, Yue Zhang.
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Keywords:Copyright © 2019 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
abnormal nocturnal behavior; epilepsy; hypoglycemia; REM sleep behavior disorder; sleepwalking