Chapter 24: Postcraniotomy Complication Management

Given her history, this patient is at high risk for postoperative seizure. Therefore, her postoperative monitoring should include electroencephalographic (EEG) monitoring and seizure prophylaxis. Her focal neurologic deficit quickly resolved, which is not unusual in the immediate postoperative setting. Her team elected for CT to rule out an urgent cerebrovascular complication, such as a subdural hematoma, which may present acutely in the postoperative period.

Postoperative patients represent a large fraction of cases seen in the NICU. Many neurosurgical procedures involve a craniotomy (removal of a section of the cranium that is replaced). Procedures that may require craniotomy include:

• Brain tumor resection

• Aneurysmectomy

• Epilepsy grid placement

• Hematoma evacuation

• Brain abscess removal

• Implantation of a deep brain stimulator

• Insertion of a monitoring probe

• Ventriculostomy

The range of postoperative complications depends on the location of the operative site, length of operation, and patient characteristics.^1,2 Adverse postoperative events (eg, neoplasm, cerebrovascular insult, high intracranial pressure [ICP]) are associated with, and often directly result from, the disease process. In a small subset of patients, craniotomy itself can lead to unintended postoperative complications. The most common postcraniotomy complications are:

General medical complications:

• Hypotension/hypertension

• Nausea

• Infections

• Deep vein thrombosis

• Pulmonary embolism

• Pneumonia

Neurologic complications:

• Cerebrovascular complications

• Cerebrospinal fluid (CSF) leaks

• Hydrocephalus

• Edema and increased ICP

• Seizures

Medical complications are common in the NICU and affect more than 50% of neurosurgical patients.³ History of psychiatric illness, asthma, carotid stenosis, and male sex are associated with increased risk of medical complications.⁴ Neurologic complications are more commonly seen in patients with carotid stenosis and preexisting mental illness.⁴ Infratentorial meningioma and craniopharyngioma are also associated with particularly high rates of neurologic and general medical complication rates.^3,4 Rates of postcraniotomy complications vary widely by procedure (Table 24-1).²

Potentially fatal complications can be managed appropriately to decrease mortality rate. Some of the most serious and potentially fatal complications include:

• Abscess formation (either subdural or intracerebral)

• Brain edema

• Hemorrhage

Different complications tend to present at different points in the postoperative course. Infections tend to present far later, while cerebrovascular events are more common during the early postoperative period. Table 24-2 presents a general perspective of the most common complications during various postoperative periods.⁶ It is not a definitive summary of all possible complications of any surgery.

Appropriate postoperative monitoring is critical for the detection and management of postoperative complications. In the patient described above, EEG monitoring was especially important as the patient was at high risk for seizure activity. ICP and cerebral blood flow (CBF) monitors are excellent for detecting pressure changes signaling brain edema or hemorrhage, but are associated with a risk of infection.⁷ EEG monitors for seizure activity are recommended, and adequate screening for postoperative seizures may require 24 hours or more of continuous EEG monitoring.⁸ Detailed neurophysiologic monitoring modalities are discussed in Section 2 of this book. Complications most commonly occur within the first 24 to 48 hours after surgery, and early intervention is critical in improving the clinical course and outcome.⁹ Generally, postoperative monitoring in the NICU includes a neurologic examination and blood pressure monitoring.

Neurologic Examination

Although intensive monitoring is readily available, especially in advanced NICUs, neurologic examination may be the earliest sign of postoperative deterioration.¹⁰ Multiple scales can be used in clinical examination of postoperative patients—the widely accepted Glasgow Coma Scale (GCS) (Table 24-3) and the newer full outline of unresponsiveness (FOUR score)¹¹ (Table 24-4). Although the GCS is a validated measure of neurologic function,^12,13 the FOUR score, a new neurologic function score, offers more subtle discrimination of neurologic function, especially in patients who are deeply comatose or on a ventilator; has a high concordance between examiners; is easy to use, even by inexperienced staff; and can predict hospital mortality or decline to the Rankin score of 3 to 6.^11,14,15

After surgery, ensure that the effects of anesthetics have sufficiently worn off. All patients should be monitored for sudden postoperative neurologic status. Perform baseline neurologic examination every hour. If this is not feasible, do it every 2 to 4 hours. If a patient's neurologic status changes (ie, GCS drop > 2), a CT scan should be ordered to rule out hemorrhage, CSF leak, edema, or infection. Common normal postoperative examination findings (often related to anesthetic side effects) and abnormal findings should be differentiated⁶ (Table 24-5). Causes of abnormal findings on postoperative examination include intracerebral hemorrhage, epidural hemorrhage, subdural hemorrhage, and brain edema.

Blood Pressure Monitoring

Postoperative hypertension

The incidence of postoperative hypertension is relatively high (30% to 80% depending on definition of hypertension²). A sudden increase in blood pressure may raise suspicion of a cerebrovascular event. Hypertension increases the risk of postoperative complications, including myocardial infarction, stroke, and cerebral hemorrhage.^16,17 It is important to discriminate postoperative hypertension from the Cushing reflexive hypertension secondary to elevated ICP. Treatment of hypertension must avoid decreasing cerebral hemodynamic parameters (cerebral blood flow, ICP, cerebral metabolic rate of oxygen) as it can lead to cerebral hypoperfusion.^2,18

First-line agents: Intravenous β-adrenergic antagonists provide adequate blood pressure control²:

• Labetalol

• Metoprolol

• Esmolol

Second-line agents: With refractory hypertension or marked bradycardia where β-adrenergic antagonists are unsuitable, angiotensin-converting enzyme (ACE) inhibitors and vasodilators are options—Blood pressure control outweighs the risks.^2,18

Blood pressure management (Figure 24-1) should be combined with appropriate pain management, as undercontrolled pain may increase blood pressure. Morphine or other opioids have sedative effects that make neurologic function more difficult to assess. Nonsteroidal anti-inflammatory drugs (NSAIDs) are favorable agents, but may need to be combined with opioid analgesics for adequate pain control.¹⁹ Abrupt administration of an antihypertensive agent may lead to a sudden decrease in cerebral blood flow—Patients should be carefully monitored when receiving an intravenous (IV) bolus of antihypertensive medication.¹⁸

Postoperative hypotension

Postoperative hypotension is not as common as hypertension (2% to 5%), but can impact recovery and is associated with adverse events such as hemorrhage.² Neurogenic and septic shock should both also be considered in cases of hypotension.

Nausea

Neurosurgical patients are at high risk of postoperative nausea (over 30% to 50%).² This may lead to volume abnormalities, including elevated ICP and blood pressure. Treat nausea with one of the following:

• IV ondansetron (4 to 8 mg)

• IV droperidol (0.625 to 1.25 mg)

• IV metoclopramide (5 to 10 mg)

If vomiting does not stop and remains severe, intracranial hypertension may be suspected, and if neurologic function deteriorates, hemorrhage is a possibility—This necessitates a CT scan (Figure 24-1).

Postoperative seizures are common. They occur within a week of surgery in anywhere from 4% to 19% of patients.²⁰ Surgery for brain tumors, brain abscesses, arteriovenous malformations (AVMs), and aneurysms have all been associated with postoperative seizures.²⁰ Patients with a preexisting seizure disorder or metabolic abnormalities are also at increased risk for seizures. Although generalized tonic-clonic seizures are the most common seizure observed in the NICU, some patients will present with neurologic deterioration and decreased level of consciousness rather than convulsions.²¹ Without EEG monitoring, comatose patients may have unrecognized status epilepticus.²² Continuous EEG monitoring is critical for detecting these less common, nonconvulsive seizures. Preoperative prophylaxis with phenytoin and continuation of therapy reduce the incidence of seizures, but inadequate dosing (10 to 20 μg/dL is ideal) is common.^23,24 Seizures may be a manifestation of other pathologic processes, such as cerebral edema, intracranial hemorrhage, meningitis, or infection. Epilepsy management is discussed in detail in Chapter 3.

Patients with a single focal seizure lasting less than 2 minutes should be monitored carefully and considered for anticonvulsants.²⁵ Generalized seizures lasting more than 1 to 2 minutes should be aggressively treated (Figure 24-2).²⁶

This patient initially presented with massive intraventricular hemorrhage (IVH) and uncontrolled hypertension, cardiac disease, and atherosclerosis. He was at high risk for hemorrhagic stroke in the postoperative period. Unfortunately, despite aggressive monitoring and prompt recognition of his hematoma, this patient had a very poor neurologic outcome, as is likely with severe IVH. Postoperative hemorrhage, which commonly includes intracerebral, subdural, epidural, and subgaleal hemorrhages, is one of the most serious complications of neurologic surgery. Improved surgical technique has reduced the incidence of postoperative hemorrhage significantly—Postcraniotomy hemorrhage occurs in approximately 1% of patients.²⁷ The most common risks for postoperative bleeding include hypertension, administration of antiplatelet agents, and other clotting abnormalities.^27,28 These are often correctable—Preoperative evaluation is critical in reducing the incidence of postoperative hemorrhage. Neurologic deterioration, especially an altered level of consciousness, in the immediate postoperative period should be followed with CT and potentially magnetic resonance imaging (MRI) with diffusion to ensure appropriate detection of hemorrhage.⁹ Urgent surgical decompression is required for many postoperative hemorrhages. Outcomes following hemorrhage are grim (80% of patients experience some permanent neurologic deficit).²⁷

This patient's unexplained fever prompted a fever workup and his injury, with skull fracture, predisposed him to bacterial infections. Prophylaxis and preoperative prevention are key in preventing postoperative infection.^29,30 Although the rates of infection are fairly low in neurosurgery, surgical techniques for minimizing infection should be used and patients should be given antibiotics with gram-positive and gram-negative coverage in the brief preoperative, intraoperative, and postoperative periods to minimize risk of infection.²⁹ Skin flora are the most common culprits in postoperative infections. A suitable regimen for broad-spectrum prophylactic operative coverage is:

• For "clean" operations: Cefazolin and cefoperazone/sulbactam have been shown to be equally effective for preoperative prophlaxis.³¹

• For "dirty" operations: Vancomycin 1.5 g/day and ceftazidime 6 g/day for 72 hours after the operation.³⁰

Patients with an external ventricular drain (EVD) or other invasive devices, especially if the device remains for an extended period of time, may contribute to a higher risk of infection—EVD management is covered in Chapter 22 of this textbook.^32-34 In addition, neurosurgical patients should be monitored for nonoperative infections, including urinary tract infections, pneumonia, and infections of various catheters.²⁵ (See Section 10 of this book for detailed nonoperative infection management.) Although neurosurgery is generally associated with low rates of postoperative infection, the following complications are possible:

• Surgical site infection

• Meningitis

• Subdural empyema

• Brain abscess

• Catheter infection, especially CSF shunts.

Management of each infection should begin with a broad-spectrum regimen (Figure 24-5), and once the organism has been identified, an antibiotic regimen should be tailored accordingly.

Surgical Site Infection

Wound infections occur in an estimate of 0% to 5.8% of cases.^29,31 Clinical symptoms including swelling and tenderness at the surgical site take at least 48 hours, possibly many days or weeks, to develop.³⁵ Once detected, wound infections should be treated immediately to prevent cranial osteomyelitis or meningitis, which can result from unrecognized and untreated wound infections.³⁶ Skull films, or CT with bony windows, may be helpful for comparison with later films in case osteomyelitis develops. Culture of the wound site will determine the specific antibiotic regimen needed. Because gram-positive cocci are the most common causes of wound infection (Figure 24-6), first-generation cephalosporins, such as cefazolin, are a good choice for initial broad-spectrum therapy.

Osteomyelitis

If repeat skull films or CT scans reveal spread to the underlying bone, excision of the infected bone flap or plate, with antibiotic treatment and drainage of the area, is critical.

Meningitis

Nosocomial meningitis may be very difficult to detect and often presents differently than community-acquired meningitis. The most common symptoms are fever and an altered level of consciousness, but these are nonspecific and easily mistaken for normal postoperative recovery.³⁶ Meningismus may be present in less than 50% of patients.³⁷ Lumbar puncture with analysis of the cell count, protein, glucose, Gram stain, and culture of the CSF are critical. However, Gram stain and cell count have low sensitivity in neurosurgical patients, and cell count may have low sensitivity, especially in patients who have had intracerebral hemorrhage.³⁷ In cases of diagnostic uncertainty, lactate levels of the CSF may prove helpful. A lactate level of over 4 mmol/L in the CSF has a high sensitivity and specificity for bacterial meningitis.³⁸ Patients should be treated with the antibiotics listed in Table 24-6.³⁹

Aseptic meningitis from surgical trauma or immune reaction to blood in the central nervous system may account for up to 70% of postoperative meningitic findings. If repeated CSF analysis yields negative findings and the patient is determined to have aseptic meningitis, antibiotics can be safely discontinued.⁴⁰

Subdural empyema

Subdural empyema (SDE) is fortunately a rare complication of craniotomy, but it is a surgical emergency and must be detected and treated immediately. Patients with subdural bacterial collections may pre-sent with fever, headache, seizures, periorbital edema, and various focal neurologic deficits.⁴¹ As with postoperative bacterial meningitis, patients with postoperative SDE tend to present with more subtle symptoms and a more insidious onset than typical SDE patients.⁴² An urgent CT scan in a patient with postoperative SDE may reveal a hypodense or isodense subdural collection with rim enhancement.⁴¹

Surgical evacuation of the abscess is critical and removal of the underlying bone flap may be necessary. Patients should be treated with postoperative medications listed in Table 24-7.⁴¹

Brain abscess

A brain abscess, like subdural empyema, is a life-threatening, rare complication that requires immediate attention. The time course of a bacterial abscess is similar to that of SDE. Symptoms may be subtle. The most common symptoms are headache and alteration in mental status.⁴³ CT has 95% to 99% sensitivity in detecting brain abscess.⁴⁴ However, the ring-enhancing lesion can be easily mistaken for other pathologic processes, including malignancy, infarction, and hematoma.⁴³ Upon diagnosis of an abscess, broad-spectrum antibiotic therapy should be as shown in Table 24-8.⁴³

Brain abscesses must be either surgically aspirated or resected, and the organism detected will determine the antibiotic therapy that is required.

This patient presented with clear fluid and no pain or swelling at her surgical site, indicating no infection. Most CSF leaks resolve within a week without intervention, but some, like this patient, may require surgical repair.¹ Although CSF leaks are relatively rare, patients who have undergone posterior fossa surgery are at higher risk for CSF leaks (up to 13% of posterior fossa surgeries may result in this complication, but there is much variation based on the specific surgical approach).⁵ Presentation of CSF leak may include:

• Direct drainage through the wound

• Otorrhea

• Rhinorrhea

Otorrhea and rhinorrhea CSF leaks are more commonly seen in more aggressive operative approaches, but intraoperative packing with bone wax has helped reduce the incidence of these complications.⁴⁵ Diagnosing a CSF leak can be challenging, as not all patients present with substantive fluid drainage. Fluid may be expressed when the patient stands or changes positions. Elevation of the patient's head may also be helpful in finding fluid.⁴⁶ If clear, nonbloody fluid can be collected, inspection can verify the identity of the drainage. If confirmation is needed, a β₂-transferrin assay is sensitive, as is glucose testing of nonbloody fluid (CSF glucose should be approximately 60% of serum glucose) to verify its identity.⁴⁶

Treatment

CSF wound leakage can be handled conservatively—Most patients will resolve within 5 to 7 days without intervention.⁵ Patients that do not resolve within this time can be treated with lumbar puncture and continuous spinal drainage—CSF should be drained at a rate of 5 to 15 mL/h.²⁵ Surgical packing for closure of the CSF fistula may rarely be required if these measures are ineffective (Figure 24-7).¹ Although meningitis and infection are potential sequelae of a CSF leak, antimicrobial prophylaxis is not indicated.⁴⁷

Hydrocephalus is particularly common after posterior fossa surgeries, ranging from 4.6% to 30.0% of operations.^5,48 It is unclear if the etiology of the hydrocephalus is related to the tumor or the surgery. The most common presenting symptom in patients with hydrocephalus is decreased level of consciousness, which is a relatively late finding. Earlier signs of hydrocephalus include headache, nausea/vomiting, gait disturbance, or abducens nerve palsy.^5,9 Hydrocephalus can also present with a CSF leak.⁵ Sudden changes in systolic blood pressure or breathing can signal an acute, potentially life-threatening change in the pressure in the posterior fossa. CT scans compared with baseline CT scans from the preoperative or immediate postoperative period can establish a diagnosis of hydrocephalus. Hydrocephalus as a result of obstruction of the ventricular drainage system can be confused with hydrocephalus as a result of generalized cerebral edema.⁹ Management is markedly different in these etiologies—CSF drainage through a ventriculostomy is indicated for obstructive hydrocephalus, but one should proceed with extreme caution in brain edema to avoid herniation.⁹

As mentioned before, brain edema can be confused with obstructive hydrocephalus. Brain edema can occur as a result of tissue manipulation during surgery, often developing 48–72 hours after the craniotomy.⁹ CT should reveal hypodense areas consistent with cerebral edema. The treatment of cerebral edema consists of:

1. ICP monitoring: A monitor of intracranial pressure provides critical information of the course of postoperative edema and is a critical tool. Maintaining a cerebral perfusion pressure of at least 60 mm Hg is imperative to prevent brain injury. Chapter 12 of this book provides more details.

2. Hyperventilation: Immediate intubation and hyperventilation is critical in patients with severe, acute edema, especially patients showing evidence of brainstem dysfunction. Patients should be hyperventilated to achieve a Pco₂ of 30-35 mm Hg.²⁵

3. Osmotic agents: Mannitol and hypertonic saline both have been shown to lower ICP.^49-52 There is controversy over which is preferred, but currently both are suitable options for managing brain edema. The target serum osmolarity of treatment is 300–310 mEq/L.²⁵

4. Steroids: Steroids are very effective for treating edema after tumor surgery, but not as helpful in other postoperative situations.^2,25 Steroids should be administered to patients who have had a tumor removed (10 mg of dexamethasone every 4 hrs).