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 Investigations

Routine laboratory tests, including complete blood count, coagulation parameters, and serum chemistry profile, including electrolytes, serum glucose, and renal function tests should be obtained prior to surgery. Previously performed tests that show normal results can be used if there has been no intervening clinical event.[12] Ordering additional preoperative laboratory tests should be guided by medical history, physical examination, and type and nature of the planned procedure.[18] A pregnancy test should be obtained for women of childbearing potential. Urinalysis may be indicated in patients susceptible to urinary tract infections, such as those with multiple sclerosis or spinal injury, and in patients undergoing a urological procedure.

Assessments of nutritional and fluid and electrolyte status is an essential component of preoperative evaluation. Malnourished patients are at increased risk for surgical morbidity and mortality.[19] Assessing serum albumin level provides information about the patient's nutritional condition. Electrolyte abnormalities, as a result of the cerebral salt wasting, inappropriate antidiuretic hormone secretion (SIADH), or central diabetes insipidus, should be closely monitored and corrected prior to surgery. Serum potassium and magnesium should be carefully monitored and corrected in patients taking diuretics because these abnormalities can predispose to perioperative arrhythmias. Similarly, it is important to monitor serum glucose during the perioperative period, especially in diabetics or patients taking steroids.

A preoperative electrocardiogram is required for patients with cardiovascular or respiratory diseases, male patients older than 40 to 45 years of age and women older than 50 years of age, and patients with multiple risk factors undergoing high-risk cardiovascular surgeries. Clinical characteristics that may necessitate a preoperative chest x-ray include smoking, recent upper respiratory infection, chronic obstructive pulmonary disease, and cardiac disease.[18] Further cardiac or pulmonary testing other than electrocardiogram or x-ray should be guided by the findings of the basic preoperative evaluation. For example, consider obtaining a transesophageal echocardiogram in patients with a history of stroke of undetermined etiology before cardiac surgery to evaluate for aortic sources of embolization. The finding of significant aortic atherosclerosis can lead to modification of the planned surgical technique to minimize the risk of recurrent stroke. Preoperative spirometry may be appropriate in patients with existing chronic pulmonary disease or asthma.[20] Furthermore, preexisting hypoalbuminemia is a powerful predictor of increased risk for postoperative pulmonary complications.[21] Pulmonary function tests should be assessed preoperatively in patients with a low serum albumin level.[20]

The type of planned surgery and the patient's clinical situation should dictate preoperative neurological testing. A frequently encountered scenario is the preoperative assessment of patients with suspected carotid stenosis undergoing major surgery. The decision should be individualized on a patient-by-patient basis. Patients with a history of stroke or TIA should be screened with Doppler ultrasound, or magnetic resonance imaging (MRI) or computed tomography (CT) angiography, if previous evaluation has not been done or if the patient's neurological status has worsened since the stroke.[22] In patients in whom an asymptomatic high-grade stenosis is detected before undergoing a major cardiovascular surgery, consider brain imaging with CT or MRI to exclude clinically silent ipsilateral territorial infarcts and intracranial MRA or CTA, or transcranial Doppler to determine the hemodynamic significance of the area of stenosis and the status of intracranial blood flow. Patients in whom carotid stenosis is judged to be symptomatic or hemodynamically significant may require preoperative carotid revascularization to minimize their perioperative stroke risk.

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