Diagnosing Rem Sleep Behavior Disorder: The Process Explained

REM sleep behaviour disorder (RBD) is characterised by a loss of muscle paralysis during REM sleep, which results in people acting out their dreams. Diagnosis of RBD should begin with a detailed clinical history, including a discussion with the patient and their bed partner or roommate. A review of any recorded videos of the person sleeping can also be helpful. The next step is to conduct a polysomnography (PSG) to verify the loss of sleep atonia and document the behaviours during sleep. PSG can also help rule out other conditions that may mimic RBD, such as sleep apnea, non-REM sleep parasomnias, nocturnal epileptic seizures, and psychiatric disorders.

A detailed clinical history

During the clinical history-taking, the healthcare provider will inquire about the patient's sleep habits, including bedtime routines, sleep environment, and any medications or substances that may impact their sleep. They will also explore the patient's medical history, focusing on neurological conditions, mental health issues, and the use of medications that can interfere with sleep. Additionally, the healthcare provider will assess the patient's overall health, including cardiovascular, respiratory, and metabolic conditions that might contribute to sleep disturbances.

The clinical history also involves a detailed description of the patient's sleep behaviour, including any unusual movements, vocalizations, or injuries that occur during sleep. It is important to determine if the patient is aware of their sleep behaviour and if they recall their dreams. The bed partner or roommate's observations are crucial in this aspect, as the patient may not always be aware of their actions during sleep.

Furthermore, the clinical history will explore the impact of the patient's sleep behaviour on their daily life, including their energy levels, mood, and ability to function during the day. It will also assess the patient's safety and the safety of those sleeping nearby, as RBD can lead to accidental injuries. The healthcare provider may recommend safety measures, such as removing hazardous objects from the bedroom and creating a safe sleeping environment to prevent injuries.

In addition to the clinical history, the healthcare provider may also review any recorded home videos of the patient's sleep behaviour. These recordings can provide visual evidence of the patient's movements and help differentiate RBD from other sleep disorders. The combination of the clinical history, observations from bed partners or roommates, and video recordings helps build a comprehensive understanding of the patient's sleep behaviour and aids in making an accurate diagnosis.

Examination of home videos

Home videos are an important tool in diagnosing REM sleep behaviour disorder (RBD). They can be used to identify abnormal behaviours during sleep and rule out other sleep disorders. The videos can be examined by a sleep specialist or neurologist and should be reviewed alongside a detailed clinical history from the patient and, if possible, their bed partner or roommate.

The videos should be examined for any unusual behaviours during sleep, such as:

• Talking, shouting, or screaming
• Kicking, punching, or grabbing
• Jumping or falling out of bed
• Pushing, biting, punching, or choking
• Other complex movements, such as smoking, giving speeches, or flying in a dream

It is important to note that not all patients will recall their dream-enactment behaviours, so the presence of a witness who can report abnormal behaviours during sleep is crucial. The videos should also be examined for the timing of these episodes, which typically occur at least 90 minutes after falling asleep and more frequently during the latter half of sleep when REM sleep is more prevalent.

Additionally, the presence of REM sleep without atonia (RWA) should be assessed, as this is a requirement for an RBD diagnosis according to the International Classification of Sleep Disorders. RWA can be identified by increased muscle tone during REM sleep, which can be observed through electromyography (EMG) of the chin and/or limb leads.

The examination of home videos can help distinguish RBD from other sleep disorders with similar presentations, such as:

• Obstructive sleep apnea
• Non-REM sleep parasomnias (e.g., sleepwalking, night terrors, confusional arousals)
• Nocturnal epileptic seizures
• Sleep-related movement disorders (e.g., periodic limb movements, trauma-associated sleep disorder, rhythmic movement disorder)
• Psychiatric disorders (e.g., post-traumatic stress disorder)

Polysomnography (PSG)

The American Academy of Sleep Medicine (AASM) provides technical recommendations for PSG acquisition and analysis in its manual, which covers specific electrode placements, data collection procedures, and criteria for scoring various sleep stages and events. The PSG report should describe the percentage of REM sleep epochs that meet the criteria for REM without atonia (RWA) to better distinguish patients with and without RBD.

PSG also helps rule out conditions that may mimic RBD, such as obstructive sleep apnea, non-REM sleep parasomnias, nocturnal epileptic seizures, periodic limb movements, and psychiatric disorders.

Ruling out other conditions

• Obstructive sleep apnea
• Non-REM sleep parasomnias (e.g. sleepwalking, night terrors, confusional arousal, and sleep-related eating disorders)
• Nocturnal epileptic seizures
• Sleep-related movement disorders (e.g. periodic limb movements during sleep, trauma-associated sleep disorder, and rhythmic movement disorders during sleep)
• Psychiatric disorders (e.g. post-traumatic stress disorder, sleep-related dissociative disorder)
• Other clinical disorders (e.g. nocturnal hypoglycemia)

A physical and neurological exam is usually carried out to rule out other potential causes, such as alcohol, medications, or narcolepsy. Due to the common co-occurrence of Parkinsonian syndromes and REM sleep behaviour disorder, doctors will also look for symptoms of Parkinson's disease, such as hand tremors or muscle stiffness.

Clinical and neurological exam

A clinical and neurological exam is an important first step in diagnosing REM sleep behaviour disorder (RBD). The exam will involve taking a detailed clinical history from the patient and their bed partner or roommate. The doctor will ask about the patient's symptoms, including any abnormal movements or vocalisations during sleep, and may also ask the bed partner or roommate to describe any behaviours they have observed. The doctor will also review any recorded videos of the patient sleeping.

The clinical and neurological exam will also involve a physical and neurological examination of the patient to rule out other potential causes of the patient's symptoms, such as alcohol or medication use, or an underlying neurological condition such as Parkinson's disease. The doctor will look for symptoms of other neurological disorders, such as hand tremors or muscle stiffness, which may indicate an underlying condition such as Parkinson's disease, Lewy body dementia, or multiple system atrophy.

If the doctor suspects that the patient may have RBD, they will then refer them for further testing, such as a polysomnogram (an overnight sleep study) to confirm the diagnosis.

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