Investigation of sleep and circadian rhythm disorders.

Diagnosis of a sleep disorders is multimodal. An overview is presented in this review. The medical history leads to a tentative diagnosis supported by questionnaires, sleep diary and objective methods. Examination may reveal upper airway problems in a patient suspected to have obstructive sleep apnoea or rigidity in an elderly patient with shouting during sleep, suggestive of rapid eye movement sleep behaviour disorder. The choice of diagnostic sleep test is based on the tentative diagnosis. Other tests (e.g., lumbar puncture, brain scan) may be indicated. Wearables pose the advantage of documenting the patients' habitual sleep and circadian rhythm.

Impaired cerebrovascular reactivity in obstructive sleep apnea: a case-control study.

OBJECTIVE: Obstructive sleep apnea (OSA) is an independent risk factor for stroke. Little is known about the cerebrovascular hemodynamic changes during apnea. Hypercapnia occurs in apneas and hypopneas, and a reduced cerebral vasodilatory response to CO2 could compromise the cerebral blood flow (CBF). Therefore, we aimed to evaluate whether the apnea-hypopnea index (AHI) affected the cerebrovascular response to CO2. METHODS: A total of 11 patients with OSA were compared to 16 controls. We assessed the cerebrovascular responses with arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) magnetic resonance imaging during hypercapnia or breath-holding tasks. RESULTS: The CBF response to CO2 was impaired with increasing AHI (average CBF: p = 0.018; gray matter: p = 0.038; white matter: p = 0.045), that is, increased OSA severity. When comparing the OSA patients to the control subjects, the OSA patients had a significantly reduced CO2 response of the white matter CBF (p = 0.04). However, the BOLD response to CO2 and the breath-holding task did not show any significant differences between OSA patients and control subjects. CONCLUSION: The cerebrovascular CO2 reactivity, measured by the CBF, was impaired with increasing AHI, that is, OSA severity. These findings may add to the understanding of the increased stroke risk found in OSA patients.

Polysomnographic indicators of mortality in stroke patients.

PURPOSE: The purpose of the study was to assess polysomnographic indicators of increased mortality risk in patients with stroke or a transient ischemic attack (TIA). METHODS: We performed polysomnographies in 63 acute stroke/TIA patients. Mortality data were collected from a national database after a 19-37-month follow-up period. RESULTS: Of the 57 stroke and 6 TIA patients, 9 stroke patients died during follow-up. All nine had moderate or severe sleep-related breathing disorders (SRBDs). Binarily divided, the group with the highest apnea hypopnea index (AHI) had an almost 10-fold higher mortality risk (hazard ratio (HR) 9.71; 95 % confidence interval (CI) 1.20-78.29; p = 0.033) compared to the patients with the lowest AHI. The patients with the longest versus shortest nocturnal wake time had a higher mortality (HR 8.78; 95 % CI 1.1-71.8; p = 0.0428). Lung disease increased mortality (HR 9.92; 95 % CI 2.00-49.23; p = 0.005), and there was a trend toward a higher mortality risk with atrial fibrillation/flutter (HR 3.63; 95 % CI 0.97-13.51; p = 0.055). CONCLUSIONS: In stroke patients, the AHI and nocturnal wake time are indicators of increased mortality risk. SRBDs in stroke patients should receive increased attention.

Sleep apnea diagnosis varies with the hypopnea criteria applied.

PURPOSE: We aimed to evaluate the three hypopnea criteria, A and B from 2007 and the revised from 2012, proposed by the American Academy of Sleep Medicine (AASM) for scoring sleep-related breathing disorders (SRBDs) in patients with acute stroke or transient ischemic attack (TIA). METHODS: Polysomnographies (PSGs) in patients with TIA or stroke were scored according to the A-, B-, and 2012-hypopnea criteria. RESULTS: Sixty-three PSGs were eligible for hypopnea scoring. There was no difference in the number of patients diagnosed with the B- and 2012-criteria. Therefore, they are mentioned as one. Forty-seven patients (75 %) were diagnosed with SRBD using the A-criteria versus 57 patients (90 %) using the B/2012-criteria (p < 0.0016). In 30 cases, a change from A- to B/2012-criteria resulted in a change in diagnosis. Ten cases of "no SRBD" changed to mild/moderate/severe SRBD. An apnea hypopnea index (AHI) >15 is a typical indication of treatment. With the B/2012-criteria, we found an additional indication of treatment in 18 patients, compared to when the A-criteria were applied (p < 0.0001). Two of these patients were labeled as no SRBD with the A-criteria. CONCLUSION: The difference is significant between the AHIs achieved by the A- and the B-/2012-hypopnea criteria, with much lower AHIs achieved with the A-criteria. As SRBD treatment lessens the risk of complications, correct identification of SRBD patients is of the utmost importance.