Sleep apnea is a common and potentially serious sleep disorder characterized by repeated interruptions in breathing during sleep. These interruptions, called apneas, can last for seconds to minutes and can occur many times throughout the night.
Obstructive Sleep Apnea (OSA): This is the most common form of sleep apnea. It occurs when the muscles in the back of the throat relax excessively during sleep, leading to a partial or complete blockage of the airway. As a result, breathing temporarily stops or becomes shallow. The brain senses the lack of oxygen and briefly wakes the person up to reopen the airway. These awakenings are often so brief that they are not remembered by the individual, but they disrupt the normal sleep cycle, leading to poor sleep quality. Common symptoms of OSA include loud snoring, choking or gasping during sleep, excessive daytime sleepiness, and difficulty concentrating.
Central Sleep Apnea (CSA): CSA is less common and occurs when the brain fails to send the appropriate signals to the muscles responsible for controlling breathing. Unlike OSA, CSA is not typically associated with physical obstructions in the airway. CSA may be related to certain medical conditions, such as heart failure or certain neurological disorders.
After suboccipital craniectomy plus C1–3 cervical laminectomy in 71 patients, with dural graft in 69, one death due to sleep apnea occurred 36 hrs post-op. Respiratory depression was the most common post-op complication (in 10 patients), usually within 5 days, mostly at night. Close respiratory monitoring is therefore recommended 1).
Sleep apnea syndrome is present in most patients with acromegaly; it is detected in up to 90% of patients with symptoms such as snoring.
Airway stenosis and pharyngeal tissue hypertrophy are typical characteristics of changes in the structure of the upper respiratory tract in patients with acromegaly who present with OSAHS. AHI is a predictor of the severity of the respiratory tract changes 2).
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Bilateral cervical cordotomy carries a risk of the loss of automaticity of breathing 3) (one form of sleep apnea, so-called Ondine’s curse) 4). Therefore, if bilateral cordotomies are desired, the second should be staged after normal respiratory function and CO2 responsiveness are verified following the first procedure, or the second stage may be done as an open procedure in the thoracic region. Review the cross sectional spinal cord anatomy for relationships of the critical tracts (spinothalamic and corticospinal) to the dentate ligament, the anterior spinal artery, respiratory and bladder areas.
Risk factors for sleep apnea include obesity, a family history of the condition, being male, being over the age of 40, and having a large neck circumference. Lifestyle factors, such as smoking and excessive alcohol use, can also contribute to the development or worsening of sleep apnea.
Untreated sleep apnea can have a significant impact on an individual's health and well-being. It is associated with various health problems, including hypertension, heart disease, stroke, diabetes, depression, and daytime fatigue-related accidents. Therefore, it is essential to diagnose and manage sleep apnea effectively.
Repetitive transient intracranial pressure waveform elevations up to 50 mmHg (ICP B-waves) are often used to define pathological conditions and determine indications for ICP-reducing treatment.
Riedel et al. showed that nocturnal transient ICP elevations are present in patients without structural brain lesions or hydrocephalus in whom they are associated with sleep apnea. However, whether this signifies a general association between ICP macropatterns and sleep apnea remains unknown.
They included 34 patients with hydrocephalus, or idiopathic intracranial hypertension (IIH), who were referred to the Neurosurgical Department, Copenhagen, Denmark, from 2017 to 2021. Every patient underwent diagnostic overnight ICP monitoring for clinical indications, with simultaneous polysomnography (PSG) sleep studies. All transient ICP elevations were objectively quantified in all patients. Three patients were monitored with continuous positive airway pressure (CPAP) treatment for an additional night.
All patients had transient ICP elevations associated with sleep apnea. The mean temporal delay from sleep apnea to transient ICP elevations for all patients was 3.6 s (SEM 0.2 s). Ramp-type transient ICP elevations with a large increase in ICP were associated with rapid eye movement (REM) sleep and sinusoidal-type elevations with non-REM (NREM) sleep. In three patients treated with CPAP, the treatment reduced the number of transient ICP elevations with a mean of 37%. CPAP treatment resulted in insignificant changes in the average ICP in two patients but elevated the average ICP during sleep in one patient by 5.6 mmHg.
The findings suggest that sleep apnea causes a significant proportion of transient ICP elevations, such as B-waves, and sleep apnea should be considered in ICP evaluation. Treatment of sleep apnea with CPAP can reduce the occurrence of transient ICP elevations. More research is needed on the impact of slow oscillating mechanisms on transient ICP elevations during high ICP and REM sleep. 5)
Treatment options for sleep apnea may include:
Continuous Positive Airway Pressure (CPAP): CPAP therapy involves using a machine that delivers a constant stream of air pressure through a mask to keep the airway open during sleep, preventing apneas.
Bi-level Positive Airway Pressure (BiPAP): Similar to CPAP but with variable pressure levels to assist with both inhalation and exhalation.
Oral Appliances: Dentists can fit individuals with custom oral appliances that reposition the jaw and tongue to help keep the airway open.
Lifestyle Changes: Weight loss, avoiding alcohol and sedatives, and changing sleep positions may be recommended to reduce sleep apnea symptoms.
Surgery: In some cases, surgical procedures may be considered to remove obstructions in the airway or to alter facial structures.
Effective treatment depends on the type and severity of sleep apnea, as well as individual factors. It's crucial for individuals with suspected sleep apnea to undergo a sleep study (polysomnography) to receive a proper diagnosis and determine the most appropriate treatment approach.
Earlier studies have indicated an important role for cerebral blood flow in the pathophysiology of central sleep apnea (CSA) at high altitude, but were not decisive. To test the hypothesis that pharmacologically altering cerebral blood flow (CBF) without altering arterial blood gas (ABGs) values would alter the severity of CSA at high altitude, we studied 11 healthy volunteers. (8M, 3F; 31{plus minus}7 years) in a randomized placebo-controlled single-blind study at 5,050 metres in Nepal. CBF was increased by intravenous (iv) acetazolamide (Az; 10mg/kg) plus iv dobutamine (Dob) infusion (2-5 ug/kg/min) and reduced by oral indomethacin (Indo; 100mg). ABG samples were collected and ventilatory responses to hypercapnia (HCVR) and hypoxia (HVR) were measured by rebreathing and steady-state techniques before and after drug/placebo. Duplex ultrasound of blood flow in the internal carotid and vertebral arteries was used to measure global CBF. The initial 3-4 hours of sleep were recorded by full polysomnography. Iv Az+Dob increased global CBF by 37{plus minus}15% compared to placebo (P<0.001), whereas it was reduced by 21{plus minus}8% by oral Indo (P<0.001). ABGs and HVR were unchanged in both interventions. HCVR was reduced by 28%{plus minus}43% (P=0.1) during iv Az{plus minus}Dob administration and was elevated by 23%{plus minus}30% (P=0.05) by Indomethacin. During iv Az+Dob, the CSA index fell from 140{plus minus}45 (control night) to 48{plus minus}37 events/hour of sleep (P<0.001). Oral Indo had no significant effect on CSA. We conclude that increasing cerebral blood flow reduced the severity of CSA at high altitude; the likely mechanism is via a reduction in the background stimulation of central chemoreceptors 6).