Sleep-disordered breathing

The normal circadian rhythm of the body guides the sleep-wake cycle and resets approximately every 24 hours. Sleep is a complex physiological process, so that sleep disturbance and disorders are commonly seen in the general population. However, the risk is notably increased following a spinal cord injury (SCI).

Sleep disturbance

Data from the 2018–19 Aus-InSCI survey of 1,579 adults with SCI demonstrated a high prevalence of sleep disturbances following injury. Sleep problems were ranked among the top five secondary health conditions by 78% of participants. Furthermore, 30% reported sleep disturbances as severe to extreme, with 62% of these individuals indicating that their sleep problems were untreated.

Sleep disorders

Sleep disorders following SCI may include:
• sleep-disordered breathing (SDB), including both obstructive and central types
• movement-related disorders, such as restless leg syndrome and spasticity issues
• circadian rhythm sleep–wake disorders
• insomnia.

Sleep disturbances—particularly sleep disorders—can profoundly impact a person with SCI, affecting daily functioning, relationships, employment, and community participation. Untreated sleep disorders are associated with reduced quality of life and negative health outcomes, including chronic pain, depression, and cognitive decline.

Sleep-disordered breathing

SDB is of particular concern following SCI. A 2021 systematic review with meta-analysis reported that SDB in people with cervical SCI was prevalent at the following severity and rates: mild (83%), moderate (59%), and severe (36%). Increased prevalence was associated with older age. However, no statistically significant differences were found based on sex, body mass index, injury duration, injury completeness, or level of cervical injury.

Overall, the prevalence of SDB is reported to be 2-9 times greater in the SCI population, compared to the general population. Hence, SDB is a significant health issue to assess and manage.

The summary below outlines causative factors in the development of SDB following SCI, along with compounding factors.

Assessment

A comprehensive assessment should involve a multidisciplinary team, the person with SCI and their support network.

General assessment may begin with noting subjective and objective indicators of sleep disturbance, including completion of various sleep screening questionnaires.

Specific assessment of SDB ideally involves polysomnography, which is an overnight sleep study using full diagnostic instruments. These typically include:

• electrooculography (EOG)– to monitor eye movement to identify sleep stages
• electroencephalogram (EEG)– to record brain wave activity
• electrocardiogram (ECG)– to record heart electrical activity
• pulse oximetry– to record heart rate and blood oxygen saturations
• electromyography (EMG) leg sensors– to detect leg muscle contractions
• infra-red video surveillance– to record overall rest versus sleep, as well as global body positions and limb movements.

Following SCI, full polysomnography is preferred, with interpretation of results and treatment trials overseen by a sleep /respiratory physician—rather than a sleep scientist. This is due to the complex risk factors for SDB that must inform both the interpretation of sleep study results and the overall management plan.

Management

Untreated SDB following SCI is associated with a reduced quality of life and negative health outcomes, but also adverse health outcomes in comparison to the general population. These include a greater prevalence of lower respiratory tract infections, cardiovascular disease, hospitalisation, and ICU admissions. In addition to this, there is also a higher mortality rate from respiratory and cardiovascular conditions.

Therefore, SDB should be considered a high clinical priority in SCI management and promptly investigated. Completion of an initial sleep study should be followed-up by a repeat sleep study every few years—particularly as chronic respiratory dysfunction and ageing begins to impact respiratory health overall.

Lifestyle modifications and health management are important, but typically positive airway pressure (PAP) therapy during sleep is also required. A multidisciplinary team review is recommended to ensure a comprehensive approach and successful implementation.

Positive airway pressure therapy (PAP)

Forms of PAP therapy, including continuous positive airway pressure (CPAP), are commonly used in the treatment of sleep apnoea following SCI. PAP therapy treats both the obstructive and central components of SDB following SCI. PAP therapy is able to support upper airway patency, address nocturnal hypoventilation and compensate for aspects of autonomic dysfunction.

However, PAP therapy requires a significant investment in trialling and education to promote comfort and compliance, for therapeutic benefit. There is sufficient evidence to suggest that this is the primary reason why PAP therapy is not more readily complied with. Potential barriers which may limit use of PAP therapy should be considered and addressed as possible. These include:

• user tolerance—adjusting to the sensory and respiratory experience of assisted breathing during sleep
• impaired upper limb function—may affect mask donning and doffing, leading to:
  • safety concerns
  • claustrophobia
• insufficient overnight care support
• a lack of accessible funding for equipment
• limited implementation support from health professionals
• a perceived lack of benefit—user may not notice immediate improvements.

Mandibular advancement devices (MADs)

Given the challenges related to tolerance and comfort with PAP therapy, there is growing interest in trialling mandibular advancement devices (MADs) for people with SCI who have SDB. One recent study in this population has showed promising results, demonstrating significant reduction in AHI and daytime sleepiness, while also improved tolerance during sleep and adherence to regular use over time. Further research is required to explore the efficacy of MADs in SDB management and SCI as an alternative to PAP therapy.

Respiratory health management

Strategies may include:

• reviewing adequacy of overall ventilation support
• implementing lung volume augmentation
• improving secretion management
• treating other respiratory diseases e.g. chronic obstructive pulmonary disease
• reviewing hygiene practices
• implementing a respiratory action plan.

Other health and supports management

Strategies may include:

• addressing weight management through diet, exercise and caloric tracking
• adopting a side-lying sleep position instead of supine, where appropriate—considering pain, pressure relief routines and functional independence
• improving pain and spasticity management using stretching, positioning supports and medications
• reviewing medications that may impair sleep
• avoiding alcohol and caffeine, particularly in the evening
• implementing sleep hygiene techniques such as regulating room temperature, reducing noise and light, maintaining a consistent bedtime, and trialling relaxation strategies
• providing psychological support to address adjustment, anxiety, depression or other mental health concerns.

Discharge and community planning

A person with SCI who has SBD and needs to implement lifestyle and respiratory management, along with PAP therapy, may also need a review of their funding, care and health professional supports for community living.

For more information on these considerations, refer to Discharge and community planning.