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

Basic Preoperative Evaluation

A complete history and physical and neurological examination are essential to identify patient-related characteristics and abnormalities that could influence the perioperative risk. A review of medical records and prior consultations is important because some neurological and neurosurgical patients may not be able to provide a complete history. Reviewing records of prior surgical procedures and anesthesia with particular attention to associated complications can help to predict future complications and to plan alternative surgical or anesthetic strategies to minimize the risk.

Medical Conditions

Several chronic conditions such as diabetes, hypertension, heart disease, arrhythmias, and epilepsy are commonly encountered in neurological and neurosurgical patients. Inquiring about existing and past medical conditions is important to identify patients at increased risk for perioperative complications. For example, patients with poorly controlled diabetes have an increased propensity toward infection and impaired wound healing.[2,3] Hypertension is an important cause of perioperative bleeding, and chronic hypertension may shift the cerebral blood flow autoregulation curve to the right, resulting in increased susceptibility to cerebral hypoperfusion after perioperative hypotensive events. These concerns necessitate adequate control of blood pressure and glucose throughout the perioperative period. Eliciting a history of cardiac disease is of critical importance. The use of epinephrine or ketamine during anesthesia should be avoided in patients with coronary artery disease because of their vasoconstrictive and cardiostimulatory effects.[4,5] In addition, the patient's ability to increase cardiac output in response to fluid shifts during surgery is an important determinant of survival after major surgeries. A history of a bleeding disorder is important to detect and reverse prior to surgery. Similarly, severe hepatic disease can result in impaired coagulation and wound healing, and should prompt the physicians to avoid sedatives, antibiotics, and anesthetics that are metabolized in the liver. Patients with a history of stroke or transient ischemic attacks (TIA) undergoing cardiac surgery are at increased risk for perioperative stroke.[6] These patients should be thoroughly evaluated to determine the cause of stroke and to ensure that they are adequately treated to minimize the risk of stroke recurrence. Obtaining a dietary history and weight changes are important because malnutrition may lead to increased perioperative mortality.

Medications

Medications for chronic pain should be continued as normal in the perioperative period as this will help to achieve postoperative pain and blood pressure control. Similarly, most antihypertensive and antiarrhythmic agents should be continued without interruption throughout the perioperative period. A sudden cessation of antihypertensives, especially clonidine and guanfacine, should be avoided to minimize the danger of rebound hypertension. The exception is angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, which should be stopped on the day of surgery because their use can be associated with refractory intraoperative hypotension.[7,8] Oral hypoglycemics should be held before surgery and substituted with sliding-scale insulin to improve perioperative glycemic control. For patients undergoing minor procedures, omitting oral hypoglycemic agent(s) on the morning of surgery and resuming it postoperatively may be acceptable.[9] The exception is metformin, which is associated with the development of lactic acidosis. It should be discontinued at least one day prior to surgery and restarted 2 to 3 days postoperatively after testing for renal function.[10]

A large number of neurological patients are on antithrombotic therapies for secondary stroke prevention or nonsteroidal antiinflammatory agents (NSAIDs) for pain. Some advocate that NSAIDs be discontinued 2 to 3 days preoperatively to minimize the risk of intraoperative bleeding. However, continuation of NSAIDs throughout most nonneurosurgical procedures is likely safe.[11] Oral anticoagulation with warfarin should be withheld 5 to 6 days before major invasive and neurosurgical procedures. The time off anticoagulation should be minimized in patients at high risk for thromboembolic complications, such as those with mechanical valves, atrial fibrillation, or history of systemic embolism including embolic stroke. Bridging therapy with heparin or heparinoids after discontinuation of warfarin and early reinitiation of postprocedure anticoagulation in these patients is advised as soon as the risk of bleeding from the surgical site is minimal. Heparin may be stopped a few hours preoperatively and restarted after surgery.[12] Continuation of warfarin during surgery is likely safe in cutaneous surgeries, dental extractions and other limited oral procedures, and diagnostic, but not invasive, endoscopy or colonoscopy.[11] Aspirin and clopidogrel are discussed in the section on cerebrovascular diseases.

Patients treated with steroids prior to surgery may require steroid supplementation during the perioperative period. Patients undergoing minor surgery should take 1.5 to 2 times their usual dose on the morning of surgery and the normal dosage the following day.[13] In case of a prolonged surgery, an additional dosage may be given perioperatively. Those undergoing major surgery should take 2 times their usual dosage preoperatively, receiving additional intravenous hydrocortisone during surgery and postoperatively, and resume the normal dosage within 48 to 72 hours.[13]

Several antiepileptic drugs can induce hepatic enzymes and alter the pharmacokinetics of anesthetic agents. Recommendations for the management of medications used to treat specific neurological disorders are summarized in Table 1 .

Physical and Neurological Examinations

Assessing the cardiovascular system and airway is an integral part of any preoperative evaluation. Special attention should be paid to the cervical spine; an unstable cervical spine, limited neck movements, and cervical cord compression are not uncommon in neurological and neurosurgical patients, especially after traumatic injuries. These patients may require cervical immobilization or in-line traction during intubation or fiberoptic intubation. A complete neurological examination is required to assess the patient's preoperative baseline neurological status. The severity of presenting neurological deficits in these patients could determine the degree of surgical urgency. Patients with a preoperative Glasgow Coma Scale score < 9 are more prone to develop hypoxia and hypercarbia, which may lead to elevated intracranial pressure.[16] These patients should be ventilated at the earliest opportunity and stabilized prior to surgery.[17]

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