Perioperative Management of Patients with Specific Neurological Diseases

Perioperative Management of Patients with Specific Neurological Diseases

By. Nagy Ghattas H. Shennoda

Outlines includes perioperative management of :Cerebrovascular Stroke.Epilepsy. Neuromuscular Disorders.Muscle Diseases.Peripheral Neuropathies.Parkinson Disease.Multiple Sclerosis.Alzheimer disease.

Ischaemic Stroke

Antiplatelet Therapy

After cessation of aspirin or clopidogrel, platelet aggregation returns to baseline in five days.Abrupt discontinuation of antiplatelet agents before surgery may be associated with increased risk for stroke recurrence due to rebound hypercoagulability.

Continuation of aspirin therapy is acceptable during regional spinal anesthesia, nerve blocks, dermatological cutaneous surgeries, dental procedures, ophthalmological procedures, peripheral vascular procedures, cardiac surgeries, and endoscopies. Clopidogrel, on the other hand, appears unsafe and should be discontinued 5 to 7 days before surgical procedures.Platelet transfusion does not restore platelet function in patients under clopidogrel, but it is efficient for patients under aspirin.

There are no studies regarding the safety of dipyridamole, alone or in combination with aspirin, during surgery, It is therefore advised to withhold it 5 to 7 days preoperatively.Antiplatelet are returned 24 hrs postoperative.

Anticoagulant therapy

Emergency surgery

Warfarin can be reversed with vitamin K and prothrombin complex concentrate (PCC), or fresh frozen plasma when PCC is not available.

In patients who are having a major surgical or other major invasive procedure, interruption of anticoagulant therapy is typically required to minimize the risk for perioperative bleeding. In patients who are undergoing minor surgical or invasive procedure (eg, dental, skin, or cataract), interruption of anticoagulant therapy may not be required. To eliminate effect of anticoagulant therapy before surgery, treatment should be stopped before surgery (~5 days for warfarin, to minimizing bleeding risk)

Perioperative Anticoagulation

In resuming treatment after surgery, it takes: - 2-3 days for anticoagulant effect to begin after starting warfarin- 3-5 h for peak anticoagulant effect after starting LMWHMost surgery/procedures done out-of-hospital and potential thromboembolic or bleeding complications occur during the initial 2 wks after surgery while patient is at home - Close patient follow-up during early postop period allows early detection and treatment of complications

Perioperative Anticoagulation

Giving bridging after surgery increases risk for bleeding; this risk depends on anticoagulant dose (therapeutic-dose > low-dose) and proximity to surgery (higher risk if given closer to surgery)Low-dose LMWH/UFH is effective to prevent postop VTE, but evidence is lacking that such regimens effective to prevent ATE

Perioperative Bridging Anticoagulation

The need for bridging is driven by patients' estimated risk for thromboembolism (TE):In high-risk patients, the need to prevent TE will dominate management irrespective of bleeding risk; the potential consequences of TE may justify bridging. In moderate-risk patients, a single perioperative strategy is not dominant and management will depend on individual patient risk assessment.In low-risk patients, the need to prevent TE will be less dominant and bridging may be avoided.

Perioperative bridging Anticoagulation

Perioperative Bridging Anticoagulation

An intermediate-dose regimen has been recently studied for bridging and is intermediate in anticoagulant intensity between a high-dose and low-dose regimen (eg, enoxaparin 40 mg BID).

Suggested Risk Stratification: Mechanical Heart ValvesHigh Risk Any mitral valve prosthesis Older (caged-ball or tilting disc) aortic valve prosthesis Recent (within 6 months) stroke or TIA.Moderate Risk Bileaflet aortic valve and at least one of: Atrial fibrillation, prior stroke or transient ischemic attack, hypertension, diabetes, congestive heart failure, age >75 yearsLow Risk Bileaflet aortic valve without atrial fibrillation and no other risk factors for stroke

Suggested Risk Stratification: Atrial FibrillationHigh Risk CHADS2 score = 5-6 Recent (within 3 months) stroke or TIA Rheumatic valvular heart disease

Moderate Risk CHADS2 score = 3-4

Low Risk CHADS2 score = 0-2 and no prior stroke or TIA

High bleeding-risk surgeries/proceduresinclude:

Urologic surgery/procedures: bladder resection or tumor ablation, nephrectomy or kidney biopsyPacemaker or ICD implantation.Colonic polyp resection, especially >1-2 cm sessile polypsVascular organ surgery: thyroid, liver, spleenBowel resection Major surgery involving considerable tissue injury: cancer surgery, joint arthroplasty, reconstructive plastic surgeryCardiac, intracranial or spinal surgery (small bleeds can have serious clinical consequences)

Non-vitamin K Antagonist OralAnticoagulant Drugs

The mean duration of interruption in the non-vitamin K antagonist oral anticoagulant drug registry was 2 days pre-procedure and 1 day postprocedure . There are, however, several issues that make the optimal pre-operative approach uncertain.Non-vitamin K antagonist oral anticoagulant drugs have a faster onset of action and a shorter half-life than warfarin.Their half-life is dependent on renal function, as well as liver function for apixaban and rivaroxaban

Subarachnoid Hemorrhage

Cardiac ischemia resulting from increased sympathetic outflow, increased cardiac afterload, or impaired contractility is common after subarachnoid hemorrhage (SAH). Preoperative evaluation of these patients should include electrocardiography, echocardiography, and measurement of serum markers of myocardial damage. These patients are also more susceptible to develop electrolyte abnormalities, in particular hyponatremia secondary to cerebral salt wasting or SIADH, which could predispose them to seizures or cardiac arrhythmias.

The patient's cardiac function and electrolytes should be optimized before undergoing surgery. Maintaining adequate hydration and euvolemia is important to minimize the risk of vasospasm during the perioperative period. In addition, the mean arterial blood pressure must be maintained within the autoregulatory range while avoiding high mean pressure to prevent rebleeding in patients with SAH due to ruptured aneurysm.

Epilepsy

The risk of perioperative seizures is proportional to the frequency of seizures at baseline.Multiple surgical factors increase the risk for seizures, such as alterations in maintenance AED therapy via absorption or scheduling changes, physical and psychological stressors as well as the use of potentially pro-convulsive anesthetics.It is preferable to maintain AED therapy as close to baseline as possible perioperatively.

Epileptic patients could be instructed to take their regularly scheduled morning AEDs with sips of water. Baseline oral AEDs should be reinitiated as soon as feasible after surgery. If enteral options are not available, there are intravenous AEDs.

Generally, lower dosages of anesthetics (eg, etomidate) tend to be pro-convulsive, while higher dosages tend to be anticonvulsive. Exceptions are opioids that tend to be only pro-convulsive. However, the majority of seizures that occur perioperatively are not related to either local or general anesthesia but to the underlying epilepsy.

Also, surgery has an impact on seizures.patients with epilepsy may have psychogenic nonepileptic convulsions, which may increase perioperatively.Additionally, recovery from anesthesia may lead to transient shivers and myoclonus.Patients with epilepsy do have more complications than those without a history of seizures. They tend to have more preoperative comorbidities and are at increased risk of postoperative complications, including pneumonia, septicemia, acute renal failure, bleeding, wound infections.

Neuromuscular Disease

Neuromuscular patients can experience various, potentially life-threatening perioperative complications. The primary goal of preoperative evaluation is to predict and minimize potential neurologic complications and enhance the surgical outcomes of patients with neuromuscular disorders.

Respiratory weakness is a common feature of neuromuscular disease, and a careful history to recognize symptoms of reduced function capacity can be useful. A history of orthopnea, mild to moderate dyspnea exacerbated by flexing at the back, insomnia, chronic fatigue, or narcolepsy should be investigated. Physical examination should include auscultation of lungs, inspection of accessory respiratory muscle use.

Dysphagia is another common symptom of neuromuscular disease, with a prevalence of up to 62% after endotracheal intubation.As neuromuscular patients can have bulbar weakness, a swallowing study for silent aspiration should be considered prior to general anesthesia

Certain drugs are known to worsen symptoms of some neuromuscular disorders. Aminoglycoside antibiotics impair neuromuscular transmission and can cause significant weakness.High-dose steroids are associated with an increased risk of critical illness myopathy after surgery, particularly when nondepolarizing neuromuscular junction blocking agents are used for intubation. Early mobilization and aggressive postoperative treatment reduce the risk of critical illness myopathy.

Myasthenia Gravis

Although many patients with myasthenia gravis achieve disease remission with the use of immunosuppressants, they can experience potentially life-threatening complications in be considered in the perioperative period. Patients and their families should be informed about the possibility of myasthenia crisis and/or prolonged ventilator use. In general, patients should keep taking anticholinergic medications as well as immunosuppressants.

Most immunosuppressant drugs do not interact with anesthetic medications, except for azathioprine, which may prolong the effect of succinylcholine and inhibit nondepolarizing neuromuscular blockers. If possible, severe myasthenia gravis should be stabilized prior to surgery using short- to intermediate-term treatment strategies, such as intravenous immunoglobulin or plasmapheresis.

Pyridostigmine and other anticholinergic medications can theoretically interfere with neuromuscular blocking agents, delaying their effect onset.Considering the risk of respiratory complications, the value of discontinuing pyridostigmine is questionable. Volatile anesthetic agents can be safely used in patients with myasthenia gravis, reducing the need for neuromuscular blocking agents.

In postoperative period, reconstitution of pyridostigmine either oral or its parenteral equivalent form can be done with half of the preoperative dose given 12 hours after the procedure, increasing to the full dose over the next 2 days to avoid cholinergic crisis.For patients who have been on steroids, a boosting dose of IV methylprednisone can also be considered before extubation.

Muscular Dystrophies

In addition, careful preoperative pulmonary assessment, including pulmonary function studies, is crucial. Preoperative pulmonary function predicts postoperative respiratory complications in muscular dystrophy patients who are undergoing scoliosis surgery and have forced vital capacity (FVC)