Acquired narcolepsy in an acromegalic patient who underwent pituitary irradiation

Narcolepsy and Hypothalamic Region Tumors: Presentation and Evolution

OBJECTIVE

Because most cases of brain tumor-associated narcolepsy have been published in the form of case reports or small series, the clinical presentation and evolution have not been well described. We sought to better define the epidemiology, etiology, and outcome of brain tumor-related narcolepsy.

METHODS

We conducted an extensive review of the literature to identify cases of narcolepsy associated with brain tumors. Only cases of brain tumors involving the hypothalamic region including the suprasellar, sellar, and thalamus were included in this study.

RESULTS

We report a child with possible narcolepsy in a child with a brain tumor. Through our literature review, we identified 25 additional cases of narcolepsy associated with brain tumors affecting the hypothalamic area. Most symptomatic narcolepsy cases were reported in children (70%). Half of the patients (13 of 25, 52%) developed narcolepsy after surgery, whereas 11 patients (44%) were symptomatic at the time of the tumor diagnosis. Ten patients had narcolepsy without cataplexy. Most cases were associated with craniopharyngioma (38%), adenoma (24%), and glioma (14%). Three, including our patient, experienced a complete resolution of symptoms. All patients underwent biopsy and were treated with adjuvant therapy. For patients with persistent symptoms, most (60%) improved following medical management of narcolepsy.

CONCLUSION

This study represents the largest compilation of patients with this association. Our study allows us to better understand the etiology and outcome of patients with narcolepsy-related brain tumors.

Sleep disturbance of adults with a brain tumor and their family caregivers: a systematic review

The high incidence and psychophysiological morbidities of sleep disturbance in cancer have been increasingly recognized. Yet, more detailed understanding of sleep disturbance and options for management have been neglected areas in both clinical care and research. Brain tumor patients have been particularly overlooked. A systematic search of the literature from 1990 to 2015 was performed to review sleep disturbance in adults with primary or secondary brain tumor and their family caregivers. Fifty eligible studies were identified, of which 12 focused on sleep, 37 reported sleep items within a health-related quality of life measure and 1 reported caregivers' sleep. No sleep intervention has been developed or tested for brain tumor patients. Sleep disturbance and somnolence were frequently reported as the most severely rated symptoms within health-related quality of life across the disease course or treatments, along with fatigue. However, sleep-focused studies yielded inconsistent results in small samples of mostly benign brain tumors in long-term remission from total tumor resection. The research using standardized, multifaceted sleep assessments, particularly in patients with malignant brain tumor and caregivers who are undergoing treatment, is seriously lacking. A more systematic examination of sleep disturbance is warranted to inform the development of better symptom management programs in this population.

Sleep disorders in patients with traumatic brain injury: a review

Traumatic brain injury (TBI) is a global problem and causes long-term disability in millions of individuals. This is a major problem for both military- and civilian-related populations. The prevalence of sleep disorders in individuals with TBI is very high, yet mostly unrecognized. Approximately 46% of all chronic TBI patients have sleep disorders, which require nocturnal polysomnography and the Multiple Sleep Latency Test for diagnosis. These disorders include sleep apnoea (23% of all TBI patients), post-traumatic hypersomnia (11%), narcolepsy (6%) and periodic limb movements (7%). Over half of all TBI patients will have insomnia complaints, most often with less severe injury and after personal assault, and half of these may be related to a circadian rhythm disorder. Hypothalamic injury with decreased levels of wake-promoting neurotransmitters such as hypocretin (orexin) and histamine may be involved in the pathophysiology of excessive sleepiness associated with TBI. These sleep disorders result in additional neurocognitive deficits and functional impairment, which might be attributed to the original brain injury itself and thus be left without specific treatment. Most standard treatment regimens of sleep disorders appear to be effective in these patients, including continuous positive airway pressure for sleep apnoea, pramipexole for periodic limb movements and cognitive behavioural therapy for insomnia. The role of wake-promoting agents and CNS stimulants for TBI-associated narcolepsy, post-traumatic hypersomnia and excessive daytime sleepiness requires further study with larger numbers of patients to determine effectiveness and benefit in this population. Future research with multiple collaborating centres should attempt to delineate the pathophysiology of TBI-associated sleep disorders, including CNS-derived hypersomnia and circadian rhythm disturbances, and determine definitive, effective treatment for associated sleep disorders.

Psychosocial and intellectual functioning in childhood narcolepsy

PURPOSE

This study reports the psychological assessment of 12 children referred to a narcolepsy clinic, using quantitative methods to describe intellectual and psychosocial functioning in childhood narcolepsy.

METHODS

The participants were six males and six females aged between 7-16 years (median age 10 years). The protocol included a clinical interview; the Wechsler Intelligence Scale for Children-III-UK; and the Parent version of the Achenbach Child Behaviour Checklist (CBCL).

RESULTS

Eleven children obtained an IQ in the average range (mean and median =100). However, a significant difference was found between verbal and performance scales in 42% of children, compared to WISC-III normative prevalence rates of 24%. CBCL results revealed that 10/12 children scored in the clinically significant range on the Total Score Index, with 9/12 obtaining scores in the significant range on the Internalizing Index. The majority of children presented with difficulties in discussing and describing distressing physical and psychological symptoms with parents and others.

CONCLUSIONS

These findings suggest that the psychosocial impact of narcolepsy extends beyond the effects of excessive sleepiness and that symptoms such as hallucinations can lead to significant psychological morbidity.

Hypocretins (orexins) and sleep–wake disorders

Since their discovery in 1998, the hypocretins (orexins)-peptides that are produced by a group of neurons situated in the posterolateral hypothalamus--have been shown to excite many CNS areas including many neuronal systems that regulate sleep and wakefulness. Animal studies indicate that hypocretins play a part in the regulation of various functions including arousal, muscle tone, locomotion, regulation of feeding behaviour, and neuroendocrine and autonomic functions. A link between hypocretin deficiency and narcoleptic symptoms was first shown in canine and rodent models of narcolepsy. Hypocretin deficiency, as shown by low or absent concentrations in CSF, was subsequently found in 90% of patients with sporadic narcolepsy-cataplexy, and less commonly in familial narcolepsy. In most other sleep-wake and neurological disorders, hypocretin concentrations are normal. Low concentrations were also found in hypothalamic disorders, acute traumatic brain injury, and a few other disorders. The exact function of the hypocretin system in sleep-wake regulation and its pathophysiological role in hypocretin-deficient and non-deficient narcolepsy as well as in non-narcoleptic, hypocretin-deficiency syndromes remain unclear.

Hypocretins (orexins): clinical impact of the discovery of a neurotransmitter

Hypothalamic excitatory hypocretin (orexin) neurons have been discovered in 1998 and found to have widespread projections to basal forebrain, monoaminergic and cholinergic brainstem, and spinal cord regions. The hypocretin system is influenced both neuronally (e.g. suprachiasmatic nucleus, GABAergic, cholinergic and aminergic brainstem nuclei) as well as metabolically (e.g. glucose, ghrelin, and leptin). Physiologically the hypocretin system has been implicated in the regulation of behaviours that are associated with wakefulness, locomotion, and feeding. A role in REM sleep, neuroendocrine, autonomic and metabolic functions has also been suggested. Pathophysiologically a deficient hypocretin neurotransmission has been found in human narcolepsy and (engineered) animal models of the disorder. Different mechanisms are involved including (1) degeneration of hypocretin neurons (mice), (2) hypocretin ligand deficiency (humans, mice, dogs), (3) hypocretin receptor deficiency (mice, dogs). Reports of low hypocretin-1 cerebrospinal fluid levels in neurologic conditions (e.g. Guillain-Barré syndrome, traumatic brain injury, hypothalamic lesions) with and without sleep-wake disturbances and, on the other hand, observations of normal levels in about 11% of narcoleptics raise questions about the exact nature and pathophysiological base of the link between hypocretin deficiency and clinical manifestations in human narcolepsy.

Symptomatic narcolepsy, cataplexy and hypersomnia, and their implications in the hypothalamic hypocretin/orexin system

Human narcolepsy is a chronic sleep disorder affecting 1:2000 individuals. The disease is characterized by excessive daytime sleepiness, cataplexy and other abnormal manifestations of REM sleep, such as sleep paralysis and hypnagogic hallucinations. Recently, it was discovered that the pathophysiology of (idiopathic) narcolepsy-cataplexy is linked to hypocretin ligand deficiency in the brain and cerebrospinal fluid (CSF), as well as the positivity of the human leukocyte antigen (HLA) DR2/DQ6 (DQB1*0602). The symptoms of narcolepsy can also occur during the course of other neurological conditions (i.e. symptomatic narcolepsy). We define symptomatic narcolepsy as those cases that meet the International Sleep Disorders Narcolepsy Criteria, and which are also associated with a significant underlying neurological disorder that accounts for excessive daytime sleepiness (EDS) and temporal associations. To date, we have counted 116 symptomatic cases of narcolepsy reported in literature. As, several authors previously reported, inherited disorders (n=38), tumors (n=33), and head trauma (n=19) are the three most frequent causes for symptomatic narcolepsy. Of the 116 cases, 10 are associated with multiple sclerosis, one case of acute disseminated encephalomyelitis, and relatively rare cases were reported with vascular disorders (n=6), encephalitis (n=4) and degeneration (n=1), and hererodegenerative disorder (three cases in a family). EDS without cataplexy or any REM sleep abnormalities is also often associated with these neurological conditions, and defined as symptomatic cases of EDS. Although it is difficult to rule out the comorbidity of idiopathic narcolepsy in some cases, review of the literature reveals numerous unquestionable cases of symptomatic narcolepsy. These include cases with HLA negative and/or late onset, and cases in which the occurrences of the narcoleptic symptoms are parallel with the rise and fall of the causative disease. A review of these cases (especially those with brain tumors), illustrates a clear picture that the hypothalamus is most often involved. Several cases of symptomatic cataplexy (without EDS) were also reported and in contrast, these cases appear to be often associated with non-hypothalamic structures. CSF hypocretin-1 measurement were also carried out in a limited number of symptomatic cases of narcolepsy/EDS, including narcolepsy/EDS associated with tumors (n=5), head trauma (n=3), vascular disorders (n=5), encephalopathies (n=3), degeneration (n=30), demyelinating disorder (n=7), genetic/congenital disorders (n=11) and others (n=2). Reduced CSF hypocretin-1 levels were seen in most symptomatic narcolepsy cases of EDS with various etiologies and EDS in these cases is sometimes reversible with an improvement of the causative neurological disorder and an improvement of the hypocretin status. It is also noted that some symptomatic EDS cases (with Parkinson diseases and the thalamic infarction) appeared, but they are not linked with hypocretin ligand deficiency. In contrast to idiopathic narcolepsy cases, an occurrence of cataplexy is not tightly associated with hypocretin ligand deficiency in symptomatic cases. Since CSF hypocretin measures are still experimental, cases with sleep abnormalities/cataplexy are habitually selected for CSF hypocretin measures. Therefore, it is still not known whether all or a large majority of cases with low CSF hypocretin-1 levels with CNS interventions, exhibit EDS/cataplexy. It appears that further studies of the involvement of the hypocretin system in symptomatic narcolepsy and EDS are helpful to understand the pathophysiological mechanisms for the occurrence of EDS and cataplexy.

Neuropeptides in hypothalamic neuronal disorders

A few examples of hypothalamic, peptidergic disorders leading to clinical signs and symptoms are presented in this review. Increased activity of corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus (PVN) and decreased activity of the vasopressin neurons in the biological clock and of the thyroxine-releasing hormone (TRH) neurons in the PVN contribute to the signs and symptoms of depression. In men, the central nucleus of the bed nucleus of the stria terminalis (BSTc) is about twice as large and contains twice as many somatostatin neurons as in women. In transsexuals this sex difference is reversed, pointing to a role of this structure in gender. Luteinizing hormone-releasing hormone (LHRH) neurons are formed in the fetal olfactory placade and migrate along the terminal nerve fibers into the hypothalamus. In Kallmann's syndrome the migration process of the LHRH (gonadotropin-releasing hormone) neurons is aborted, which explains the joint occurrence of hypogonadotropic hypogonadism and anosmia in this syndrome. In postmenopausal women, the neurons of the infundibular nucleus hypertrophy and become hyperactive because of the disappearance of the estrogen feedback and contain hyperactive peptidergic neurons. Climacteric flushes may be caused by hyperactivity of the neurokinin-B or LHRH neurons in this nucleus. The hypocretin (orexin) neurons in the perifornical area are involved in sleep. In narcolepsy with cataplexy, a loss of these neurons, probably due to an autoimmune process, is found. Obese subjects with a mutation in the gene that encodes for leptin, the preproghrelin gene, or the alpha-melanocyte-stimulating hormone (alpha-MSH) gene have been described. Decreased numbers and activity of the oxytocin neurons in the PVN may be responsible for the absence of satiety in Prader-Willi syndrome. Moreover, a glucocorticoid receptor polymorphism is associated with obesitas and dysregulation of the hypothalamus-pituitary-adrenal axis. In contrast, two single nucleotide polymorphisms (SNPs) of the AGRP gene have been associated with anorexia nervosa.