Background
Craniopharyngiomas (CPs) are rare brain tumors of the sellar region that most likely arise from embryonic remnants of the craniopharyngeal duct epithelium, also known as Rathke pouch epithelium [
1]. CPs develop along the pituitary-hypothalamic axis, from the sella turcica to the brain third ventricle. Approximately 50% originate in the third ventricle floor, within the infundibulum and/or of tuber cinereum, including the hypothalamus, and spread predominantly into the cavity of the third ventricle [
2]. CPs account for 0.5–2.5 new cases per 1 million population per year, with 30% and 50% of all cases presenting during childhood and adolescence [
1]. CPs are the most common non-neuroepithelial intracerebral neoplasm in children (< 18 years of age), counting 5%–11% of intracranial tumors in this age group. In childhood and adolescents the adamantinomatous histological type with cyst formation is the most common [
2].
Despite a low-grade histological classification (WHO grade I), CP may have a malignant clinical course owing to the hypothalamic-pituitary location and tumor-related and/or treatment-related injury to these areas.
At the time of diagnosis, primary signs are frequently nonspecific manifestations of increased intracranial pressure (such as nausea and headache), visual impairment (losses of visual acuity and visual field) (62%–84%), and endocrine deficits (52%–87%) [
2,
3]. Growth impairment have been recognized in patients before diagnosis, while significant weight gain suggesting hypothalamic obesity may occur over time [
2].
Treatment for CP may include either radical surgical excision or subtotal resection followed by focal radiation therapy. Overall survival reported in pediatric cohorts ranges from 83% to 96% at 5 years, from 65% to 100% at 10 years, and 62% at 20 years [
2]. Despite high survival rates, quality of life is commonly impaired in long-term survivors due mainly to neuroendocrine sequelae caused by the damage of the hypothalamic-pituitary region [
1].
The hypothalamus plays a crucial role in regulating vital functions, such as the endocrine system and metabolic processes and in controlling hunger, thirst, and thermoregulation and its injury can lead to significant endocrinological, neurological, and neurocognitive impairments (especially in memory, learning, and school performance areas). Furthermore, the hypothalamus represents a key component of the sleep–wake regulation system being the suprachiasmatic nucleus identified as the master clock of the circadian rhythm [
4,
5].
Growing data in the literature demonstrate the increased risk of sleep disorders after the onset of tumors involving the hypothalamic area or after their treatment. Sleep fragmentation, impaired sleep quality and excessive daytime sleepiness (EDS) are commonly reported in CP with a pattern of circadian rhythm characterized by early morning awakening, followed by an extra period of sleep during the afternoon [
5‐
7]. Cases of secondary narcolepsy have also been reported, particularly in children (70% of cases of narcolepsy), with CP being the prevalent type (38%) (8). Moreover, several data prove that suprasellar cancer survivors are more likely to have a greater risk for sleep-disordered breathing [
9,
10]. Patients undergoing hypothalamic surgery may lose the ability to downregulate appetite, exhibit abnormal food-seeking behavior and rapid weight gain, and develop obesity, resulting in excessive daytime sleepiness through various mechanisms, such as the increased risk of developing obstructive sleep apnea and augmented circulating levels of pro-inflammatory cytokines which in turn impair sleep [
11].
Sleep disturbances assessment plays an essential role in patient management, considering that sleep disturbances can negatively impact several biological functions, cognition, and mood.
Here we describe two cases of patients with CP who developed paroxysmal manifestations, initially misdiagnosed as epileptic episodes, expression of a severe sleep disorder.
Discussion
Knowledge about the long-term outcome of tumors involving the hypothalamic area and treatment in pediatric patients has increased in recent years. Hypothalamic dysfunction in children with CP is identified in 35% of patients at diagnosis and in up to 65%–80% of patients after treatment [
13]. Long-term complications decrease the quality of life of many long-time survivors [
14].
Although growing literature data prove an association between hypothalamic tumors and sleep disturbances, the etiology of sleep disorders is not yet fully understood, and several factors appear to be involved. This report describes two patients with CP who developed “paroxysmal episodes” initially misdiagnosed and subsequently defined as the expression of a severe sleep disorder.
Patient 1 exhibited events characterized by psychomotor slowing with afinalistic movements of the upper limbs initially defined as epileptic seizures. Careful collection of anamnestic data and targeted diagnostic work-up revealed a sleep disorder with hypersomnolence, fragmented nocturnal sleep, hypnagogic hallucinations, sudden loss of muscle tone and a severe sleep-related breathing disorder.
The second patient showed an even more severe phenotype characterized by myoclonic jerks, temporal and spatial disorientation, psychomotor agitation, and oneiric stupor like episodes. A comprehensive clinical data collection allowed to diagnose an altered sleep–wake rhythm, fragmented sleep, reduced alertness, and presumed hallucinatory events. Interestingly, during polysomnography recordings, we documented peculiar findings, such as the destruction of the wake-NREM sleep-REM sleep boundaries and the simultaneous occurrence of elements of different sleep phases. In literature, the asynchronous occurrence of the various components of the different states has been named
status dissociatus [
15], a condition representing a negative prognostic sign, in which elements of one state of being (wake, NREM sleep, and REM sleep) pathologically intrude into another. Extreme dissociation situations that determine the complete loss of any conventionally defined state of being and the circadian pattern determine a condition known as Agrypnia Excitata, a syndrome characterized by loss of sleep and permanent motor and autonomic hyperactivation, related to three different clinical conditions, fatal familial insomnia, Morvan syndrome, and delirium tremens [
16].
As for our patients, several conditions may have contributed to the clinical and electrophysiological findings.
Sleep/wake cycles are hypothesized to result from a balance between both circadian and homeostatic influences, with the hypothalamus playing an essential role in regulating the circadian rhythm. Interestingly, current models of sleep regulation suggest that the hypothalamus by hypocretin production plays an essential role in stabilizing wakefulness or sleep after one of these states has been reached through a flip-flop switch [
4]. Therefore, hypothalamic injury can cause disturbances in sleep regulation [
13]. Literature data reported increased daytime sleepiness in one-third of children with CP, with 40% prevalence in the severely obese children [
13]. Irregular bedtimes, frequent nighttime activity, and inappropriate daytime episodes of rest in CP survivors have been recognized by performing actigraphy [
17]. A similar irregular pattern was observed by the actigraphy study in Patient 1.
Evidence of both melatonin deficiency and irregular circadian function in CP survivors has been reported by Lipton et al., suggesting a profound dysfunction of the circadian pacemaker of which melatonin rhythm serves as a marker [
17]. These authors hypothesized that the complete loss of the circadian melatonin rhythm might indicate a disruption of daytime circadian arousal mechanisms, leaving homeostatic sleep drive unopposed and thus contributing to sleep disruption in these patients. Interestingly, literature data indicate that treatment with melatonin in CP patients with severe daytime sleepiness results in improved daytime sleepiness [
18], as confirmed in Patient 2.
Notably, Patient 1 was diagnosed with secondary narcolepsy, and treatment with pitolisant has been started. Cases of secondary narcolepsy in patients with tumors involving the hypothalamic area have been reported in the literature [
8]. Interestingly, a low cerebrospinal fluid (CSF) level of hypocretin-1, the wake-promoting neuropeptide typically reduced in patients with narcolepsy type 1, has been detected in a CP patient with symptomatic narcolepsy (sleep latency < 2 min and 3 SOREMPs at the MSLT; no cataplexy). This suggests the possibility that surgical removal of hypothalamic tumor could result in defective production of orexin and consequently induce daytime somnolence [
19]. However, in a further study involving five patients who underwent surgical removal of a space-occupying lesion in the hypothalamic/pituitary region, normal CSF hypocretin values were found, thus indicating other factors causing hypersomnia [
20]. Interestingly, treatment with wake-promoting agents has shown beneficial effects in CP-related hypersomnolence [
10,
21].
Patients with tumors involving the hypothalamic area have an increased incidence of sleep-disordered breathing, both obstructive and central sleep apneas, responsible for excessive daytime sleepiness and reduced alertness [
9,
10]. Moreover, apneas and hypopneas can trigger parasomnias, as in the case of Patient 2. Various factors are responsible for the increased incidence of sleep-disordered breathing. First, patients undergoing hypothalamic surgery may develop obesity [
22], as both our patients, resulting in an increased risk of sleep-disordered breathing. However, O’Gorman and colleagues who conducted a cross-sectional study of obese CP and obese controls showed that sleep-disordered breathing (including both central and obstructive sleep apneas) was increased in CP patients than in BMI-matched controls [
23], underlying the direct role of the hypothalamus in the regulation of respiratory activity [
24]. Interestingly, O’Gorman et al. also showed that CP-related respiratory dysfunction is not compensated by hormone replacement therapies, as also observed in our two cases.
In conclusion, on the basis of current knowledge, tumors affecting the hypothalamic area may be responsible for the onset of sleep disorders through various mechanisms. The diagnosis of sleep disorders is crucial, considering that sleep has an essential role on general health, cardiovascular and metabolic well-being, and immune system functioning [
25,
26]. Moreover, sleep disturbances are associated with decreased cognitive abilities, increased anxiety and depression, and decreased perceived well-being [
27].
The cases detailed in our report highlight that the clinical manifestation of these dysfunctions can be difficult to diagnose and can lead to misdiagnosis and inappropriate treatment that can harm the patient’s health and the quality of life of patients and their families. Furthermore, the diagnosis can be challenging because these patients do not clinically report sleepiness even when it is objectively present [
7]. These findings support the need to incorporate comprehensive sleep assessment in survivors from childhood brain tumors involving the suprasellar/hypothalamic region. Furthermore, the occurrence of paroxysmal episodes of uncertain origin requires differential diagnosis between epileptic seizures and events that may be manifestations of sleep disturbances. The accurate anamnestic data collection pointing to examine the clinical features of the episodes and a long-monitoring of sleep–wake activity (long-term Video-EEG, PSG, actigraphy) is crucial.