Anaesthesia and restless legs syndrome

Abstract

Editor, A 67-year-old woman presented for left breast needle localized excision biopsy. Her hypertension was controlled by diltiazem, bendrofluazide, and irbesartan. She had had restless legs syndrome (RLS) since the age of 13 and took pramipexole (a dopamine agonist) 125 μg once daily for this, usually in the late afternoon, when her symptoms were worst. She was not aware of any anaesthetic problems previously. Preoperatively, she had self-administered her antihypertensive medication, but not her pramipexole because she was symptom free. After placement of standard monitoring equipment, a 20G cannula was inserted into the dorsum of her right hand. Immediately after preinduction, her blood pressure (BP) was 160/90 mmHg. After preoxygenation, anaesthesia was induced with 75 μg fentanyl and 240 mg propofol. A size-4 disposable laryngeal mask airway was inserted, and spontaneous respiration continued throughout the anaesthetic, which was maintained using sevoflurane in an air/oxygen mixture (FiO2 0.6). One litre of Hartmann's solution and 50 mg cyclizine was administered intravenously. Five minutes after skin incision, her BP increased to 180/100 mmHg. She received a further 25 μg fentanyl, 1 g of paracetamol and 75 mg diclofenac sodium intravenously, and the monitored minimum alveolar concentration of sevoflurane was increased from 1.1 to 1.3. Her BP remained between 160/90 and 190/100 mmHg for the duration of the half-hour procedure. Her heart rate was 75–85 beats min−1 and her respiratory rate was 19–24 beats min−1. The wound was infiltrated with 20 ml of 0.5% bupivacaine after skin closure. On rapid emergence from anaesthesia, she was very agitated, complaining of pain in her legs relieved slightly by vigorous movement. She was administered 30 mg dihydrocodeine orally and 125 μg of oral pramipexole. Thirty minutes later, she reported good relief from her leg pains and her BP gradually settled to 120/60 mmHg. RLS affects 7–10% of adults (0.5–1% children) of mainly European origin, with increased prevalence among women and patients aged 60–70 years. The condition is under-recognized in the surgical population. Aetiologically, genetic and environmental factors are implicated: familial inheritance is seen, but a specific gene has not been found and specific causation remains uncertain [1]. RLS may be a primary condition, or be secondary to iron deficiency, renal failure, pregnancy, or the use of certain medications (dopamine antagonists, neuroleptics, selective serotonin reuptake inhibitor and tricyclic antidepressants, antihistamines, caffeine, alcohol, nicotine) [2]. The diagnosis is clinical, requiring an urge to move the legs (and less commonly other parts of the body) usually accompanied by an uncomfortable sensation, occurrence at rest, improvement with activity, and worsening of symptoms in the evening or at night. RLS has disruptive effects on sleep quality and daily life. Treatment of secondary causes of RLS may result in improvement or resolution of symptoms. Approximately one-third of patients require medication for symptomatic relief. Dopamine agonists (pramipexole, ropinirole, rotigotine), anticonvulsants (gabapentin), benzodiazepines (clonazepam, temazepam), and opioids (codeine, tramadol) may be beneficial. Patients with RLS should be scheduled for morning operating lists. Preoperatively, they should be encouraged to take their usual RLS medication. Premedication with benzodiazepines and opioids should be considered. Certain drugs can exacerbate the condition and should be avoided perioperatively, including butyrophenones (haloperidol, droperidol), sedative anihistamines (cyclizine – the likely cause of exacerbation in out patient), dopamine antagonist antiemetics (metoclopramide, prochlorperazine), and opioid antagonists (naloxone). 5-HT3 receptor antagonists should be used for antiemesis. Ketamine may be preferred for the induction of anaesthesia [3]. Involuntary leg movements may persist after the administration of spinal or epidural anaesthesia, but may be minimized by the addition of opioids to intrathecal or (continuous) epidural local anaesthesia. Anecdotally, intravenous magnesium [4] and physostigmine [5] have provided symptomatic control. The use of graduated compression stockings and calf compressors may also be beneficial [6]. Postoperatively, patients should be encouraged and assisted to mobilize early, and adequate (opioid) analgesia should be given, as immobility and pain can exacerbate symptoms [7]. Iron supplementation should be considered perioperatively, particularly when operative blood loss is likely to be significant.