Diagnosis of sleep disorders

As already mentioned, insomnia is the most common cause of sleep disorders. This disease is characterized by prolonged falling asleep, frequent nocturnal awakenings, prolonged wakefulness during the night, superficial sleep, early morning awakening, despite sufficient time and suitable conditions for sleep, which causes daytime sleepiness, memory and attention impairment, decreased performance, social dysfunction. Deterioration in the daytime, patients note at least 3 times a week. Insomnia is explained by the fact that “thoughts are spinning” in the head and they “cannot relax”.

Insomnia often develops as a reaction to a stressful event, in which case the diagnosis is acute insomnia. With long-term insomnia, behavioral and neurophysiological mechanisms develop that support brain hyperactivation and prevent normal sleep. Insomnia lasting more than 3 months becomes chronic. Chronic insomnia is detected, according to various sources, in 61.5% of people in the general population, which is comparable to the prevalence of diabetes mellitus. Women suffer from insomnia 1.5-2 times more often than men, people over 65 - 2 times more often than in middle age.

Risk factors for developing insomnia:

  • personal characteristics of the patient (increased anxiety and emotionality);
  • existing diseases (anxiety and depressive disorders, musculoskeletal or joint pain, cardiovascular diseases);
  • violations of sleep hygiene (night work, shift work, the habit of falling asleep with the lights or TV on, daytime sleep).

However, in the debut of insomnia, patients, as a rule, note a stressful situation (conflicts at work, in the family or in another area of communication), the appearance of a particular disease, a flight to another time zone. Different risk factors play a role in different age groups. So, in old age, comorbidities and medications become more important. After retirement, a common cause of sleep disturbance is a change in the daily routine (daytime sleep, long stay in bed reading, watching TV). Analysis of risk factors and triggers of insomnia is important for the selection of etiotropic and pathogenetic therapy.

Complaints with insomnia, as a rule, consist in a subjective feeling of lack of sleep, therefore, the severity of insomnia and dynamics during therapy can be assessed using questionnaires: the Insomnia Severity Index, the Pittsburgh Sleep Inventory, the questionnaire for scoring the subjective characteristics of sleep, and the Dysfunctional Beliefs Scale. sleep attitude (to assess the severity of thoughts that support abnormal sleep behavior and exacerbate insomnia).

Polysomnography (PSG) is not useful for diagnosing insomnia because sleep disturbances can vary greatly from one night to the next, and the effect of unfamiliar surroundings causing increased anxiety in such patients can skew the results of the study. At the same time, with the phenomenon of paradoxical insomnia, when patients incorrectly estimate the duration of their sleep, PSG helps to demonstrate that the objective duration of their sleep significantly exceeds the subjectively perceived one.

Respiratory disorders during sleep

Respiratory disorders during sleep in adults are predominantly represented by obstructive sleep apnea syndrome (OSAS). This disease is more common among men aged 40 to 64 years, with a frequency of 3-8%, for women of the same age group, the prevalence is 2%. Breathing disorders during sleep are associated with an increased risk of cardiovascular disease and mortality (mortality rate of 11% over 5 years), metabolic disorders. With OSAS, noisy breathing and snoring are observed, which later transforms into respiratory arrest during sleep. The cessation of breathing in some cases is followed by awakening, accompanied by physical activity. In most cases, patients do not actively complain, because they do not notice violations, and they go to the doctor when snoring and respiratory arrest begin to disturb relatives. Diagnostic difficulties arise when a patient with OSAS complains of light sleep, frequent awakenings, lack of alertness, and headaches upon awakening. Such complaints resemble the symptoms of insomnia, and the correct diagnosis requires further questioning. Elevated blood pressure during the night and in the morning indicates the activation of the cardiovascular system due to hypoxia. Frequent urination during the night is a consequence of increased secretion of natriuretic peptide. An important diagnostic sign is daytime sleepiness due to an objective lack of sleep, which leads to falling asleep in an environment that is not conducive to rest: at work, at a lecture, in transport, driving a car. With insomnia, the state of hyperactivation, on the contrary, makes it difficult for patients to sleep during the day.

Factors predisposing to the development of OSAS are overweight, certain constitutional features: short thick neck, large tongue, retrognathia, micrognathia, high domed palate (occur in Apert, Crouzon syndromes), III-IV degree of airway narrowing in the Mallampati test, soft tissue enlargement pharynx (tonsillomegaly, long uvula, low hanging soft palate or narrowing of the airways due to palatine arches).

Differential diagnosis between OSAS and insomnia is very important, since these conditions require fundamentally different treatment, and sleeping pills, often prescribed for insomnia, can depress the respiratory center and aggravate respiratory disorders, which is dangerous in OSAS.

If OSA is suspected, it is recommended to use the Epworth Sleepiness Scale, the Sleep Apnea Syndrome Screening Scale. However, PSG with registration of respiratory parameters remains the "gold standard" of diagnostics. This study allows you to confirm the diagnosis of OSA and determine the degree of its severity. Less informative and accurate, but a simpler method is cardiorespiratory monitoring, which records breathing parameters. An even more simplified diagnostic method is pulse oximetry (blood saturation measurement), which can be done at home. Cardiorespiratory monitoring and pulse oximetry with a sufficiently high accuracy can detect severe respiratory disorders during sleep. However, in patients with mild to moderate OSAS, the accuracy of diagnosis is reduced. Thus, if OSA of moderate and mild degree is detected, the patient should be referred for PSG to clarify the diagnosis.

As a result of the instrumental examination, the apnea / hypopnea index (AHI) is determined, which is calculated as the number of episodes of respiratory disorders (apnea and hypopnea) per 1 hour of sleep. An AHI of <5 hours is considered normal. Based on PSG data, OSA varies in severity:

  • mild degree: AHI 5-15 hours;
  • average degree: AHI 15-30 hours;
  • severe: AHI >30 hours.

The choice of treatment method depends on the severity of respiratory disorders.

Restless legs syndrome

Restless legs syndrome (RLS) occupies a leading position among sleep movement disorders, which occurs more often in older people and with a frequency of 2-3% in the general population. The main complaint is a feeling of discomfort, the need to move the legs (less often, the arms or the whole body) that occurs at rest. When moving, discomfort disappears, so patients are forced to constantly change the position of their legs in bed, and sometimes get up and walk. Symptoms tend to occur late in the evening and in the first half of the night. When presenting such complaints, it is important to exclude a polyneuropathic syndrome. Often, patients complain not of discomfort in the legs, but of difficulty falling asleep, which can lead to an incorrect diagnosis. For differential diagnosis with insomnia, it is important to clarify what prevents falling asleep and what the patient does when he cannot fall asleep (whether he moves his legs, gets out of bed).

RLS can develop both initially and against the background of other diseases and functional conditions: iron deficiency anemia, uremia, diabetic and alcoholic polyneuropathy, vascular diseases of the lower extremities, arthropathies, spinal cord injuries, radiculopathies, essential tremor, Parkinson's disease, rheumatic diseases, pregnancy. The dopaminergic system probably plays a role in the pathogenesis of the disease, as evidenced by the more frequent development of RLS while taking antidepressants and antidopaminergic drugs, as well as the regression of symptoms in the treatment of dopaminergic drugs. The International Restless Legs Syndrome Severity Rating Scale is recommended to assess the severity of RLS. If RLS is suspected, it is important to conduct a full clinical examination of the patient, exclude primary diseases that can cause RLS: conduct a blood test for latent iron deficiency (ferritin level), glucose, creatinine, urea, vitamin B12, folic acid, as well as electroneuromyography in if polyneuropathy is suspected. PSG is performed in cases of difficulty in making a diagnosis, for example, in an atypical course of RLS, combined with insomnia, OSA, periodic limb movement syndrome (PLMS).

SPDC is manifested by involuntary stereotyped movements of the limbs during sleep - dorsiflexion of the big toes, but other joints may also be involved. The duration of such movements is 0.5-5 s, the intervals are 20-90 s, the series include 4 or more movements. A series of movements are accompanied by cerebral activation, which on PSG looks like a desynchronization of the rhythm, and sometimes awakenings. Most often, a series of movements are observed in the period from 24:00 to 02:00. The prevalence of the syndrome is about 6% in the population, and in the group of people over 60 years old it increases to 34%. Despite the high prevalence, PDCS is difficult to diagnose, because small movements are imperceptible to both patients and their relatives, and frequent nocturnal awakenings and prolonged wakefulness during the night remain the main complaint. It is possible to suspect SPDC at an outpatient appointment by revealing the absence of a connection between complaints and stressful situations, the low effectiveness of hypnotics and antidepressants prescribed for insomnia. The differential diagnosis of SPDC is carried out with epilepsy, startling when falling asleep, behavioral disorders in the REM phase of sleep, increased motor activity in OSAS. An accurate diagnosis of SPDC is facilitated by PSG with registration of an electromyogram of the anterior peroneal muscles.

A high comorbidity of SPDC with RLS was revealed, which may be due to a similar pathogenesis associated with a deficiency of the dopaminergic system. At the same time, the intensity of movements in SPDS correlates with the severity of RLS manifestations, which can be used in the diagnosis and evaluation of the effectiveness of treatment.

Night cramps (sudden involuntary painful muscle contractions), as well as RLS, require differential diagnosis with vascular and joint diseases, mono- and polyneuropathies, radiculopathies, sodium and potassium deficiency. These complaints often develop against the background of intense physical exertion, during pregnancy and active growth.

Sleep disturbances may be the main complaint in parasomnias, which are quite common in the population: sleepwalking in 2% of people, sleepwalking in 4.4%, night terrors in 2.2%, bruxism in 8.2%, enuresis in 5%, nocturnal nightmares (frequent in 5.8%, occasionally in 29%). These parasomnias can be the cause of nocturnal awakenings, superficial sleep. Parasomnias are 10 times more common in children than in adults and tend to disappear as they get older. Sleepwalking, night terrors, enuresis that persist or first appear in adulthood require exclusion of the epileptic nature of seizures and PSG. Another important reason for differential diagnosis is the stereotype of seizures in epilepsy and their diversity in parasomnias. Most often, complaints of sleep disturbances occur with nightmares. This phenomenon, like insomnia, can reflect a person's reaction to stress when he experiences a threatening situation in a dream.

Nighttime sleep may be disturbed in REM sleep behavior disorders (REMS). Patients with RPPS complain of sleeping, screaming, and motor activity, often aggressive and traumatic for the patients themselves and their loved ones (associated with the content of dreams), followed by awakening. By themselves, such complaints are a highly sensitive and specific factor in the diagnosis of RPPS. If complex partial epileptic seizures with confusion are suspected, PSG with video monitoring is indicated. An objective study allows us to identify in which phase of sleep the described seizures develop: awakenings in RPS occur in the REM sleep phase, when the most emotionally colored dreams occur, while epileptic seizures develop in the non-REM sleep phase.

RPPS, being a pathognomonic symptom of Parkinson's disease and other synucleinopathies, appear several years before the onset of motor disorders and can serve as precursors of the subsequent disease. RPPS are more common in men, debut at the age of 60-70 years.