Restless legs syndrome and sleep disorders — the approach to the sleepy patient viva

Interpretation

The examiner presents a clinical scenario — a patient with poor sleep, daytime sleepiness, restless legs or snoring — and asks: "How do you characterise this disorder, what is your differential, and how do you investigate and manage it?"

• Take a structured sleep history that separates the four common disorders. Ask about snoring and witnessed apnoeas, choking or gasping (OSA), the urge to move the legs, worse at rest and evening, relieved by movement (RLS), difficulty initiating or maintaining sleep with daytime impairment (insomnia), and sleep attacks with cataplexy, sleep paralysis and hypnagogic hallucinations (narcolepsy). Quantify sleepiness with the Epworth Sleepiness Scale and always take a partner's report.^[3]
• Apply the right screening tool. STOP-BANG for OSA risk (3 or more = high risk), the IRLSSG criteria and IRLS severity scale for RLS, a sleep diary and Insomnia Severity Index for insomnia, and the Cataplexy Emotional Trigger Questionnaire for narcolepsy.^[1]
• Interpret the right investigation. Polysomnography calculates the AHI (mild 5 to 14, moderate 15 to 30, severe over 30) for OSA. Ferritin (under 75 ug/L) defines reversible iron deficiency in RLS. PSG with MSLT (mean latency under 8 minutes with 2 or more SOREMPs) and CSF hypocretin-1 (low in type 1) confirm narcolepsy.^[5]

Key points

The examiner will probe each of these; be ready to defend them at viva depth:

1. RLS pathophysiology and the iron-dopamine link. Brain-iron deficiency (even with normal peripheral ferritin) disrupts the A11 dopaminergic descending pathways and opioidergic tone, producing the circadian urge to move. Always check ferritin and replace if under 75 ugL, because iron is the commonest reversible cause.^[1]
2. RLS treatment ladder and augmentation. Iron first, then an alpha-2-delta ligand (gabapentin, pregabalin) as preferred first-line, or a non-ergot dopamine agonist (ropinirole, pramipexole, rotigotine). The cardinal long-term complication of dopamine agonists is augmentation — earlier onset, spread to the arms, shorter relief — managed by tapering the agonist, switching to an alpha-2-delta agent, rechecking iron, and considering an opioid.^[1]
3. OSA mechanism and why it is a cardiovascular disease. Sleep-related loss of genioglossus tone allows the pharynx to collapse, producing intermittent hypoxia and reoxygenation, sympathetic surges, oxidative stress and intrathoracic pressure swings. This drives resistant hypertension, atrial fibrillation, heart failure, stroke and increased mortality — untreated OSA roughly doubles cardiovascular risk.^[2]
4. OSA management — CPAP is gold standard. For moderate-to-severe OSA, CPAP plus weight loss, alcohol and sedative avoidance, positional therapy, and a mandibular advancement device for mild disease or CPAP intolerance. A commercial driver needs a driving restriction until treated.^[3]
5. Insomnia — CBT-I first, not pills. The hyperarousal model (failure of the VLPO sleep switch) is best treated by CBT-I — sleep restriction, stimulus control, cognitive restructuring — which is more effective than hypnotics and durable. Reserve z-drugs for under 4 weeks and avoid long-term benzodiazepines (dependence, falls, cognitive impairment).^[4]
6. Narcolepsy — hypocretin loss and REM intrusion. Autoimmune destruction of lateral-hypothalamic hypocretin/orexin neurons (HLA-DQB1*06:02) destabilises the sleep-wake switch, allowing REM intrusion (cataplexy, sleep paralysis, hallucinations). Treat with scheduled naps, modafinil/armodafinil for sleepiness, and sodium oxybate for cataplexy.^[5]
7. REM sleep behaviour disorder as a prodrome. Dream enactment from loss of REM atonia is a prodrome to alpha-synucleinopathies (Parkinson disease, dementia with Lewy bodies, multiple system atrophy) by years to decades — name it to show depth.^[5]

References

1. Trenkwalder C, et al. Comorbidities, treatment, and pathophysiology in restless legs syndrome. Lancet Neurol 2018.^[1]
2. Ayas NT, et al. Cardiovascular consequences of obstructive sleep apnea. Curr Opin Cardiol 2016.^[2]
3. Gottlieb DJ, Punjabi NM. Diagnosis and Management of Obstructive Sleep Apnea: A Review. JAMA 2020.^[3]
4. Trauer JM, et al. Cognitive Behavioral Therapy for Chronic Insomnia: A Systematic Review and Meta-analysis. Ann Intern Med 2015.^[4]
5. Bassetti CLA, et al. Narcolepsy - clinical spectrum, aetiopathophysiology, diagnosis and treatment. Nat Rev Neurol 2019.^[5]

References5ShowHide

1. [1]Trenkwalder C, Allen R, Högl B, et al. Comorbidities, treatment, and pathophysiology in restless legs syndrome. Lancet Neurology, 2018.PMID 30244828
2. [2]Ayas NT, Taylor CM, Laher I, et al. Cardiovascular consequences of obstructive sleep apnea. Current Opinion in Cardiology, 2016.PMID 27652812
3. [3]Gottlieb DJ, Punjabi NM. Diagnosis and Management of Obstructive Sleep Apnea: A Review. JAMA, 2020.PMID 32286648
4. [4]Trauer JM, Qian MY, Doyle JS, et al. Cognitive Behavioral Therapy for Chronic Insomnia: A Systematic Review and Meta-analysis. Annals of Internal Medicine, 2015.PMID 26054060
5. [5]Bassetti CLA, Adamantidis A, Burdakov D, et al. Narcolepsy - clinical spectrum, aetiopathophysiology, diagnosis and treatment. Nature Reviews Neurology, 2019.PMID 31324898