48.2.1 Monitoring Physiologic Markers

Airway management following vestibular schwannoma surgery requires concise communication between the surgical team and the anesthesia provider. Ideally, the patient undergoes a nonstimulating emergence and uneventful extubation. In addition to allowing for prompt neurologic assessment, the removal of the endotracheal tube reduces coughing or bucking. These behaviors have been associated with various early postoperative intracranial complications including intracranial hemorrhage, cerebral edema, and tension pneumocephalus. However, indiscriminate extubation can put the airway in danger. In patients with larger tumors or neurofibromatosis type 2 (NF2), microsurgical dissection may encroach upon the lower cranial nerves. In rare cases where these nerves are damaged, or brainstem stroke has occurred, protective airway reflexes can be diminished or absent leading to poor airway protection and an increased risk of aspiration. In addition, if extubation is performed too early, the patient may require brief positive pressure mask ventilation, which potentially increases the risk of cerebrospinal fluid (CSF) leak and/or tension pneumocephalus. A final consideration during emergence from general anesthesia is the risk of significant tongue swelling and airway obstruction in the rare scenario where the prone or sitting position was used or inadequate bite block placement was performed.

After extubation, the airway and cardiovascular systems must continue to be monitored closely. This is in part because the brainstem plays a critical role in both systems. Thus, brainstem compression from hematoma can often manifest as subtle variations in the ventilatory status, most commonly hyperventilation, hypoventilation, and intermittent apnea. With significantly elevated intracranial pressure, the Cushing reflex may be observed, characterized by the triad of increased blood pressure, irregular breathing, and bradycardia. Strict arterial blood pressure parameters (systolic < 140; diastolic < 90) are also placed to decrease the possibility of intracranial hemorrhage. Routine daily labs including a complete blood cell count and basic metabolic profile may also be ordered at the discretion of the surgeon. Though electrolyte abnormalities are not common following vestibular schwannoma surgery, hyperglycemia can occur in the setting of postoperative corticosteroid administration.

48.3.1 Intracranial Complications: Hemorrhage, CSF Leak, Meningitis, Hydrocephalus

A 2004 meta-analysis found the incidence of CSF leak following vestibular schwannoma surgery was between 9.5 and 10.6%.s. Literatur Fortunately, careful postoperative care can decrease the likelihood of a leak occurring. Such measures include elevating the head of bed to ≥30 degrees, as well as the scheduled administration of prophylactic antiemetics, antitussives, and stool softeners. In addition to these measures, a conventional mastoid dressing or compression wrap is placed at the time of surgery and maintained for 3 days postoperatively. Once removed, the incision, forehead, and pinna are inspected for signs of wound breakdown or ulceration. If an incisional CSF leak is identified at this time, local management can be very effective, with published success rates between 63 and 71%.s. Literatur In these cases, the surgical site should be sterilized with Betadine, and the incision oversewn with 2–0 Nylon suture. If a tense pseudomeningocele is present, sterile aspiration may be performed. The mastoid dressing is reapplied firmly, and bedrest is enforced for several days. In the setting of CSF rhinorrhea, local conservative measures are unlikely to be sufficient, with published success rates between 6 and 8%.s. Literatur In these cases, as well as cases of CSF otorrhea, lumbar drain and/or surgical exploration is often required.s. Literatur A complete discussion of CSF leak prevention and care can be found in Chapter 47.

Other intracranial complications include postsurgical hematoma and meningitis. Intracranial hematoma occurs in only 1 to 2% of surgical cases.s. Literatur Intracranial hematomas are often identified on a postoperative CT scan obtained within 24 hours of surgery, or by changes in neurologic status. This underscores the importance of hourly neurological checks performed by nursing and at least daily examinations performed by the surgical team. The interested reader may refer to Chapter 45 for further discussion of hematoma prevention and management. Treatment is emergent surgical evacuation. In addition to the aforementioned measures, all patients receive 24 hours of antibiotic prophylaxis against gram-positive organisms to help protect against meningitis and superficial infections. Cephalosporins are generally preferred.

48.3.2 Vestibulopathy

Disequilibrium or vertigo is a common complaint following vestibular schwannoma microsurgery. In a retrospective review among pooled patients with varying surgical approaches, 45.5% of postoperative patients complained of vestibular disturbance.s. Literatur The acute treatment of vertigo is divided into rehabilitation and medical vestibular suppression. Numerous studies have examined the utility of vestibular rehabilitation on postsurgical outcomes, with the majority advocating in favor of early rehabilitation efforts.s. Literatur These studies and others are discussed in greater detail in Chapter 69. Vestibular suppressants can help ameliorate any acute vestibular disturbances, but should be used judiciously, with the caveat that they may result in mental status changes that could be mistaken for obtundation. In addition, they may retard central vestibular compensation, and prolong the duration of the vestibulopathy. For these reasons, vestibular suppressants should be discontinued once vertigo that is perceived while the patient is still at rest has ceased, and the patient’s spontaneous nystagmus has started to resolve—ideally within 1 to 3 days from the time of surgery.