Differentials
Nocturnal epilepsy
SIGNS / SYMPTOMS
May be associated with head-turning and involuntary upper limb movements. Postictal confusion may be mistaken for daytime somnolence.
INVESTIGATIONS
Electroencephalogram (EEG) may show evidence of seizure activity. MRI of the brain may demonstrate structural lesion responsible for seizure activity.
Sleep-disordered breathing
SIGNS / SYMPTOMS
Nocturnal arousals may occur secondary to sleep-disordered breathing. Periodic limb movements of sleep (PLMS) may occur secondary to these arousals. A history of snoring, dry mouth on wakening, and morning headache may be present.
INVESTIGATIONS
Polysomnography will demonstrate nocturnal hypopnea, apneas, or respiratory effort-related arousals.[1]
Sleep starts
SIGNS / SYMPTOMS
These may be associated with brief contractures of the extremities during sleep.
INVESTIGATIONS
Electromyography (EMG) recordings during polysomnography will differentiate between sleep starts and PLMD.
Rapid eye movement sleep behavior disorder (RBD)
SIGNS / SYMPTOMS
Body movements may occur as dreams and are re-enacted during rapid eye movement (REM) sleep.
INVESTIGATIONS
PLMS predominantly occur during stages 1 to 2 of sleep, as demonstrated by EEG during overnight polysomnography. EMG will also differentiate between PLMS and other movements in RBD.
Restless legs syndrome (RLS)
SIGNS / SYMPTOMS
The main symptom of the disorder is the urge to move the legs, which is accompanied by symptoms of dysesthesias such as creeping, crawling, tingling, cramping, or aching of the extremities. Due to the circadian timing of RLS symptoms, the dysesthesias can cause insomnia, which can lead to increased sleepiness and tiredness, which in turn increases RLS symptoms.
INVESTIGATIONS
An initial diagnostic workup for RLS should include a serum ferritin level.
Iron deficiency anemia
SIGNS / SYMPTOMS
Patients usually present with fatigue, low energy level, pallor, or dyspnea on exertion. History specific to iron deficiency as a cause of anemia includes unusual cravings for ice or nonfood items and RLS.
INVESTIGATIONS
CBC (including hemoglobin and hematocrit, platelet count, MCV, MCH, MCHC, red cell distribution width) with peripheral smear, reticulocyte count, and an iron profile.
Obstructive sleep apnea
SIGNS / SYMPTOMS
Typical presenting symptoms include excessive daytime sleepiness, restless sleep and episodic gasping, and episodes of apnea during sleep.
INVESTIGATIONS
Polysomnography is the definitive test for diagnosis.
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