Insulinoma Masquerading as Rapid Eye Movement Sleep Behavior Disorder: Case Series and Literature Review

Is hyperinsulinemia a possible clinical explanation underlying the myth of Erysichthon?

BACKGROUND

An insulinoma is an endocrine tumor of the pancreas, originating from the beta cells, and has a prevalence of 4 cases per 1 million patients. Insulinomas often follow a "90% rule": 90% are benign [1, 2], 90% originate in the pancreas, 90% are approximately 2 cm wide, and 90% are isolated. Individuals with an insulinoma may have episodic bouts of hyperinsulinemic hypoglycemia. Typically, an insulinoma is indicated by hypoglycemic symptoms which are a result of catecholamine reaction and neuroglycopenia. There is increased secretion of insulin in patients with an insulinoma despite having lower glucose levels.

PURPOSE

This paper examines the myth of Erysichthon and speculates whether the symptoms experienced by him are possibly related to those found in patients with an hyperinsulinoma.

METHODS

The myth of Erysichthon was taken from various sources (i.e. Hesiod, Callimachus, Ovid) and examined. Symptoms of Erysichthon were then examined.

RESULTS

The myth of Erysichthon depicts various sympathoadrenal and neuroglycopenic symptoms including anxiety and abnormal behaviour which can be found in insulinomas. Insulinomas may often present a diagnostic challenge due to their deceptive nature and overlapping symptoms with other disorders such as neurologic disease. Insulinomas inducing weight loss resemble Calamachus's account of Erysichthon whose body is finally emaciated, even though having polyphagia.

CONCLUSION

The myth of Erysichthon provides an interesting range of clinical symptoms which I have argued relate to symptoms found in patients with an insulinoma. Although, insulinomas were unknown in ancient medical lore, this paper has speculated that based on Erysichthon's symptoms, the possibility of an insulinoma cannot be ruled out.

REM sleep behavior disorder as a complex condition with heterogeneous underlying disorders: clinical management and prognostic implications [Commentary]

PURPOSE

To review how REM sleep behavior disorder (RBD) is a complex condition with heterogeneous underlying disorders; and to review clinical management issues and prognostic implications.

METHODS

PubMed literature search and contents from the first textbook of RBD (2018).

RESULTS

RBD, with its core objective diagnostic feature of REM-without-atonia (RWA) documented by video-polysomnography, can emerge during the entire lifespan, and can initially present as an idiopathic (isolated) condition (iRBD), or can be associated with a broad spectrum of disorders including narcolepsy, alpha-synuclein neurodegenerative disorders (esp. Parkinson's disease [PD] and dementia with Lewy bodies [DLB]), paraneoplastic neurological syndromes and autoimmune disorders, CNS lesions (e.g., tumors, stroke), other neurological disorders, psychiatric disorders (PTSD, mood disorders), can be triggered by antidepressant/other medications, and can emerge acutely with drug withdrawal states, toxic-metabolic states, etc. Important clinical issues include the evolution of iRBD to PD/DLB in most middle-aged and older patients over a period of years to several decades, with compelling prognostic implications, along with the hope of enrolling these patients in future clinical trials to test promising disease-modifying therapies. Also, the strong link of RBD with narcolepsy needs further investigation. Parasomnia overlap disorder involves RBD and NREM parasomnias that can be idiopathic or linked with a broad range of clinical disorders. RBD usually responds to therapy consisting mainly of melatonin and/or clonazepam at bedtime. The complex associations of RBD with OSA are being increasingly investigated. RBD mimics with dream-enactment need to be recognized for diagnostic and management purposes, including severe OSA, NREM parasomnias, PLMD, nocturnal seizures, and other conditions.

CONCLUSIONS

The clinical and research RBD fields span across the disciplines of neurology, pulmonary, psychiatry, psychology, and pediatric sleep medicine, along with physical medicine and rehabilitation medicine, other allied disciplines, and the basic and clinical neurosciences.

Effective Treatment of Adult Parasomnias with Keishikaryukotsuboreito in Four Cases

Parasomnias are undesirable behaviors or experiences during sleep that manifest clinically as abnormal behavior, emotions, and nightmares. We herein report four elderly parasomnia patients who were successfully treated for abnormal nocturnal behaviors, including rapid eye movement (REM) sleep behavior disorders, with Keishikaryukotsuboreito (KRB), a Japanese traditional herbal medicine. KRB resolved nocturnal violent behaviors and sleep walking without any adverse effects. In one patient, occipital dominant spike-wave complexes induced by 3-Hz photic stimulation were reduced after KRB treatment, suggesting that KRB has inhibitory effects on brain irritability. KRB may represent a safe therapeutic option for treating parasomnias in the elderly.

REM sleep behavior disorder: Mimics and variants

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia with dream-enactment behaviors occurring during REM sleep and associated with the lack of the physiological REM sleep muscle atonia. It can be isolated and secondary to other neurological or medical conditions. Isolated RBD heralds in most cases a neurodegenerative condition due to an underlying synucleinopathy and consequently its recognition is crucial for prognostic implications. REM sleep without atonia on polysomnography is a mandatory diagnostic criterion. Different conditions may mimic RBD, the most frequent being obstructive sleep apnea during sleep, non-REM parasomnia, and sleep-related hypermotor epilepsy. These diseases might also be comorbid with RBD, challenging the evaluation of disease severity, the treatment choices and the response to treatment evaluation. Video-PSG is the gold standard for a correct diagnosis and will distinguish between different or comorbid sleep disorders. Careful history taking together with actigraphy may give important clues for the differential diagnosis. The extreme boundaries of RBD might also be seen in more severe and complex conditions like status dissociatus or in the sleep disorders' scenario of anti IgLON5 disease, but in the latter both clinical and neurophysiological features will differ. A step-by-step approach is suggested to guide the differential diagnosis.

Insulinoma resembling a rapid eye movement sleep behavior disorder: a case report

Some patients with insulinoma present with neuropsychiatric symptoms and are often misdiagnosed with psychiatric disease. We present the case of a 72-year-old Japanese female who exhibited violent behavior while asleep and received a diagnosis of suspected rapid eye movement sleep behavior disorder (RBD). She was admitted to the psychiatry ward after receiving levomepromazine 25 mg intramuscularly. The patient’s blood glucose level was 27 mg/dL at the time of hospitalization, and a biochemical examination revealed that her insulin level was 9.1 µU/mL and C-peptide level was 2.16 ng/mL. A contrast-enhanced computed tomography revealed a mass 8 mm in diameter in the pancreatic head. The diagnosis was changed from RBD to insulinoma. The sleep behavior disorder disappeared after continuous glucose administration. After enucleation of the insulinoma, the administration of glucose was discontinued, and her blood glucose levels recovered. This case suggests that insulinoma should be considered by physicians and psychiatrists in the differential diagnosis of patients with symptoms presenting as RBD.

Sleep disorders in the elderly: Diagnosis and management

Compared with younger people, elderly people show age‐related sleep changes, including an advanced sleep phase and decreased slow‐wave sleep, which result in fragmented sleep and early awakening. Multiple etiologies contribute to insomnia in the elderly, consistent with the observation that elderly people are likely to have comorbid conditions and medications. When elderly individuals complain of insomnia, it is important to assess treatable medical conditions and medication use that may be responsible for the insomnia before the use of hypnotics is initiated. Also, screening for primary sleep disorders, such as sleep apnea syndrome, restless legs syndrome and rapid eye movement sleep behavior disorder, is essential. We review sleep disorders commonly observed in the elderly and describe their diagnosis and management.

Spontaneous hypoglycemia: diagnostic evaluation and management

Spontaneous hypoglycemia is a puzzling clinical problem and an important reason for referral to endocrinologists. Several clinical conditions such as insulinomas, non-insulinoma pancreatogenous hypoglycemia syndrome, insulin autoimmune syndrome, postprandial hypoglycemia (reactive hypoglycemia), non-islet cell tumor hypoglycemia, primary adrenal insufficiency, hypopituitarism, and critical illness can be associated with spontaneous hypoglycemia. Rarely, in patients with mental health issues, factious hypoglycemia from extrinsic insulin use or ingestion of oral hypoglycemic agents can obfuscate the clinical picture for clinicians trying to identify an organic cause. In those presenting with Whipple's triad (symptoms ± signs of hypoglycemia, low plasma glucose, and resolution symptoms ± signs after hypoglycemia correction), a 72-h supervised fast test with measurement of plasma insulin, c-peptide, pro-insulin, and beta-hydroxybutyrate levels, coupled with plasma/urine sulphonylurea screen, forms the first step in diagnostic evaluation. A mixed meal test is preferable for those with predominantly postprandial symptoms. Additional non-invasive and/or invasive diagnostic evaluation is necessary if an organic hypoglycemic disorder is suspected. With the aid of a few brief clinical case scenarios, we discuss the diagnostic evaluation and management of spontaneous hypoglycemia through this comprehensive article.