Published on 13/03/2015 by admin
Filed under Neurosurgery
Last modified 13/03/2015
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CHAPTER 25 Surgical Planning
Overview
Martin Weiss, Gabriel Zada, Alexander A. Khalessi
Comprehensive planning represents an axiomatic prerequisite for any neurosurgical procedure. “Failing to prepare is preparing to fail” holds particularly true in neurosurgical cases given the unforgiving nature of the human nervous system. Thorough preoperative consideration of the technical goals and potential pitfalls ensures the safest and most efficacious outcome for the patient. Effective planning allows the surgeon critical flexibility and latitude in managing deviations from the intended operative course. Indeed, the experience and ability to detect and handle the most adverse intraoperative events should be a goal for any surgeon. By taking the necessary steps to ensure adequate preparation for a case, the surgeon may prevent or avoid many significant neurosurgical complications.
Any surgical procedure demands a working preoperative diagnosis. Effective intervention requires a theoretical understanding of the pathophysiology involved or a directed effort to acquire further information. The surgical plan should therefore not only be based on a working diagnosis but also designed to accommodate changes in the operative plan as the case proceeds. Admittedly, even sound planning generates an incomplete preoperative state of information. Intraoperative findings or surgical pathology results, if anticipated, allow the reasoned pursuit of alternative surgical goals. Due consideration of nonsurgical diagnoses (e.g., prolactinoma, lymphoma) and alternative modalities (e.g., medical therapy, radiation therapy, radiosurgery) represents a crucial component of preoperative planning. Surgical planning thereby seamlessly blends with a larger treatment plan to minimize morbidity and optimize timely diagnosis and treatment of disease.
This chapter outlines a generalized approach to preoperative neurosurgical planning, emphasizing key considerations and adjunctive measures essential to optimization of patient outcomes beyond the incision.
Before any neurosurgical procedure, the surgeon must complete a comprehensive evaluation of the patient. Detailed history, physical examination, and review of the patient’s laboratory results and radiographic studies are paramount. Symptom time course and onset represent central features of the suspected disease and complement a focused neurological history. Pertinent negatives must be duly considered, and a strict accounting of preoperative deficits will be critical to establishment of a baseline with which to compare the patient’s postoperative examination findings. Moreover, inquiring about the side of hand dominance is significant in many cranial procedures. Further review of a patient’s past medical and surgical history, medications, allergies, and any pertinent social or familial considerations should be undertaken.
A complete review of systems is routinely performed. The physical and neurological examination should be performed soon before the procedure and documented in the medical chart. The complete neurological examination includes an assessment of mental status and speech ability, cranial nerve function (including the first cranial nerve), motor and sensory function, reflexes, and cerebellar and gait testing. Formal visual field and acuity examination may be indicated before selected cases if sellar or suprasellar disease exists. Rectal examinations for tone, volition, sensation, and the bulbocavernosus reflex may be necessary in instances of spinal disease. Other aspects of the patient’s overall medical status demand consideration in every case; many neurosurgical patients will have significant comorbidities requiring preoperative attention. The goals of surgery should always be considered as they relate to the patient’s overall medical status and personal preferences.
Routine laboratory values are indicated before any nonemergent surgical procedure and should be obtained to screen for a number of underlying systemic conditions that may pose a risk to a patient undergoing general anesthesia and surgery. A qualitative β-human chorionic gonadotropin assessment should be performed for every woman of childbearing age before surgery. Baseline renal function and electrolyte levels are determined and evaluated further as necessary. Any suggestion of infection, such as an elevated white blood cell count, positive cultures, elevated erythrocyte sedimentation rate, or elevated C-reactive protein level, should be considered, especially in elective cases or if hardware implantation is planned.
Underlying anemia must be worked up and corrected accordingly. Any suggestion of bleeding diathesis or coagulopathy should be investigated further and corrected. Preoperative laboratory investigations geared toward these issues include platelet count, prothrombin time (international normalized ratio), partial thromboplastin time, and bleeding time (if necessary). Many patients currently take anticoagulant or antiplatelet agents for a number of underlying medical comorbidities. Plans for discontinuation or reversal of these agents (or perhaps initiation of these agents in select endovascular cases) should be addressed at least 1 week before surgery.
Blood typing and screening, or crossmatching for reserve units and additional blood products, should be requested from the blood bank and verified in advance. If sellar disease exists, a full or selective endocrine panel is drawn to assess for deficiencies in any number of hormonal axes. The thyroid and cortisol axes are of paramount importance, and deficiencies must be identified and repleted before any surgical procedure is performed. Ruling out nonsurgical lesions, such as prolactinomas, additionally necessitates judicious review of preoperative laboratory work.
Preexisting cardiac disease is commonly encountered in the neurosurgical patient population. Preoperatively, patients should undergo a detailed cardiovascular history to assess exercise tolerance and to screen for angina or congestive heart failure. Should there be preexisting disease or if a patient has significant risk factors, clearance or risk assessment from a cardiologist may be required before an elective case. A 12-lead electrocardiogram and plain chest film are obtained in the majority of adult patients before routine surgery. If further cardiac work-up is indicated, exercise treadmill testing, echocardiography, nuclear medicine study, or coronary angiography may be performed to further assess the degree of cardiac risk.
Hypertensive patients require adequate blood pressure control on multiple visits before undergoing general anesthesia for an elective case. In general, any cardiac condition that poses a risk to the patient’s overall condition should be addressed before an elective neurosurgical procedure. The degree of cardiac risk, if present, must always be accounted for and weighed against the urgency of the neurosurgical procedure. Any perioperative measures that may improve cardiac monitoring or function should be planned in conjunction with the anesthesia team, and include invasive cardiac monitoring and perioperative medications. In the setting of baseline anemia or anticipated blood loss, large-bore intravenous access is critical to the timely delivery of blood products and prevention of a hypovolemic intraoperative insult.
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