Preoperative Evaluation of Patients With Neurological Disease

Kathrin Lieb, MD; Magdy H. Selim, MD, PhD

Disclosures

Semin Neurol. 2008;28(5):603-610. 

In This Article

Preoperative Evaluation for Patients With Specific Neurological Disease

Neuromuscular Diseases (Muscular Dystrophies, Myotonias, Amyotrophic Lateral Sclerosis, Myasthenia Gravis)

Patients with muscular dystrophy, myotonia, or amyotrophic lateral sclerosis (ALS) undergoing surgery have an increased risk for respiratory and cardiac complications. The risk of life-threatening cardiac dysrhythmia and depression of cardiac contractility should be carefully considered, and cardiac function should be evaluated preoperatively by electrocardiography, echocardiography, and telemetry. Patients with an atrioventricular conduction delay should not receive halothane or other medications, such as atropine, that can further slow cardiac conduction. Preoperative pulmonary assessment should include spirometry with measurements of forced-vital capacity (FVC), maximal inspiratory and expiratory (MEP) pressures, and peak cough flow (PCF). For patients with FVC < 30%, preoperative use of noninvasive positive pressure ventilation should be considered. For patients with ineffective cough, defined as PCF < 270 L/min or MEP < 60 cm H2O, preoperative manual- and mechanically assisted cough should be considered. Patients with muscular dystrophy are more sensitive to the myocardial depressant effects of inhaled anesthetics, and are prone to cardiac arrest during induction of anesthesia that uses volatile anesthetics alone or in combination with succinylcholine.[31] Succinylcholine may also cause hyperkalemia that can cause lethal cardiac dysrhythmias and is linked to malignant hyperthermia in patients with neuromuscular disease. Inhalational anesthetic agents have also been implicated as a cause of acute rhabdomyolysis, resembling malignant hyperthermia, in these patients.[32] Sensitivity to nondepolarizing neuromuscular blocking agents is also enhanced, resulting in an increase in both peak effect and duration of action. Therefore, all malignant hyperthermia triggering agents and succinylcholine must be avoided.[33] A total intravenous anesthetic technique for induction and maintenance of general anesthesia, such as propofol and a short-acting opioid, are preferred.[33] Patients with ALS can also have autonomic dysfunction, increasing their risk for cardiovascular complications, and pharyngeal muscle dysfunction, which increases the risk for aspiration pneumonia.

Patients with myasthenia gravis are at significant risk for pulmonary complications. Risk factors that increase the likelihood of postoperative respiratory insufficiency are duration of the disease longer than 6 years, history of chronic respiratory disease, treatment doses of pyridostigmine > 750 mg/day, and preoperative vital capacity under 3 L.[34] Although preoperative drug treatment may reduce the need for postoperative mechanical ventilation,[35] anticholinesterase drugs should be stopped the day before surgery, if the clinical status of the patient allows it, or on the morning of surgery because they increase the effect of succinylcholine (which is inactivated by plasma cholinesterase) and inhibit the effect of nondepolarizing neuromuscular blocking agents. The need for anticholinesterase drugs is decreased in the first 48 postoperative hours. These drugs must be restarted carefully and titrated to avoid the risk of a cholinergic crisis.[35] Intravenous neostigmine can be used to avoid fluctuating blood levels of these drugs during the perioperative period. Patients with myasthenia are highly sensitive to nondepolarizing agents, needing only 20 to 50% of the drug compared with other patients.[35] Even small amounts of nondepolarizing agents can cause a significant respiratory muscle paralysis. Succinylcholine should also be avoided and carefully titrated short-acting nondepolarizing muscle relaxants, such as mivacurium or atracurium, should be considered for paralysis.[36] Agents affecting the neuromuscular junction, such as antiarrhythmics, calcium-channel blockers, and certain antibiotics, should be avoided.[35] Similarly, all the risk factors which predispose to neuromuscular functional impairment must be controlled; i.e., hypothermia, hypokalemia, and acidosis.

Patients with neuromuscular disorders have greater sensitivity to the respiratory depressant effects of opioids, barbiturates, and benzodiazepines. Such agents should be avoided or used with caution, particularly during the perioperative period. Preoperative cessation of smoking, chest physical therapy, use of bronchodilators, and treatment of respiratory infections are encouraged to minimize postoperative pulmonary complications. Postoperative deep breathing exercises or incentive spirometry are also recommended.[20]

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