Neurological Disorders: Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) as the name implies is characterized by episodes of apneas or hypopneas during seep, and is caused by an obstruction.

Apnea means complete stoppage of breathing, a lesser such episode is called as hypopnea (partial stoppage of breathing). The duration of these episodes in this context should be 10 or more seconds.

Basically this condition is about breathing difficulties during sleep caused by an obstruction to the breathing. The obstructive nature of this disease is explained below.

Sleep disordered breathing is another term used for this condition because the apnea and hypopnea episodes occur during sleep but not when the patent is awake, in the night or day.

OSA is being diagnosed recently with increasing frequency; this is because the awareness about this condition is increasing with both doctors and patients.

People with the following features are more prone to develop this condition;

• Obesity
• Short neck
• Male gender
• Elderly & middle aged
• Chronic smoking
• Diabetes mellitus etc.

The cause for Obstructiv Sleep Apnea is a partial or complete blockage of air movement through the airways during sleep. In normal people the air entries to the lungs is adequate, during both awake & sleep periods, but in these patients air entry is compromised due to the airway blockage as discussed below.

The muscle tone during sleep contributes for the maintenance of patency of airways and this prevents the collapse of the airways. But in OSA patients for some reason the muscle tone is not adequate during sleep and this results in shrinkage of the airway diameter and compromises the air flow to the lungs. Increased amount of soft- tissues around the neck region, for example due to obesity, may also compress the airways especially during the sleep period, either alone or in conjunction with the decreased muscle tone of the airway muscles.

The moderate to severe grades of OSA can have serious impact on the health.

The health issues attributable to OSA are broadly divided into either primary or secondary.

The primary issues:

These concerns are due to the direct effect of OSA itself. The quantity and quality of sleep is below par in these patients so while they are awake they might fee sleepy, dull and lethargic. Their mental functioning and alertness may be compromised due to this and can have grave consequences on both their professional and personal/social life. No need to highlight the perils of driving under the cloud of drowsiness.

Patients with OSA present with lot of snoring and this can be annoying to their bed partners. They also many times manifest with abnormal leg movements (PLMS or periodic limb movement disorder) and this can bother the bed partner too.

The secondary issues:

These are related with the effect of the abnormal pathological consequences due to OSA on various tissues and organs in the body.

These are few such secondary consequences;

• HTN (hypertension or High blood pressure)
• Heart-attacks
• Strokes
• Chest pain due to heart problem (angina)
• Palpitations (abnormal perceptions of one’s own heart beats)
• Pulmonary-hypertension (increased blood pressure in the blood vessels of lungs)
• Increased risk of death due to above reasons

Patients with Obstructive Sleep Apnea frequently present with these manifestations;

• Increased day time somnolence (sleepiness)
• Lot of snoring while sleeping
• Cessation of breathing while sleeping (partial or complete)
• PLMS, these are abnormal jerking movements during sleep
• Increased irritability, fatigue, decreased concentration, mood disorders, headache etc

Since snoring happens only during sleep patients cannot recall them. The snoring, apneas/hypopneas, PLMS are all typically noticed by patient’s family members, spouse for example.

Although OSA may be diagnosable clinically, however to confirm the diagnosis and to guide with the treatments a polysomnography (sleep study) is recommended.

If patient has only mild OSA then generally no treatment is required. For moderate OSA either mandibular splints or CPAP is tried. For severe OSA CPAP is tried. Some patients require BiPAP and other modalities.

Weight loss is strongly recommended as well as optimization of sleep hygiene.

If Sleep Apnea patient doesn't adequately respond to above measures then surgical options are explored. There are myriad surgical choices and they all basically try to widen the pharyngeal area and increase the air entry to the lungs.

A neurologist commonly encounters these patients in the clinical practice.