Medication Summary
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Preoperative and postoperative medications include the following:
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Steroids (dexamethasone): For brain edema and inflammation
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Antiepileptics (phenytoin, levetiracetam): Seizure prophylaxis or treatment
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Osmotic diuretics (mannitol): Given intraoperatively to reduce brain bulk
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Prophylactic antibiotics (cefazolin, vancomycin, clindamycin): Gram-positive coverage reduces the incidence of infection from scalp flora
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Local anesthetic (lidocaine with epinephrine): Local pain relief with vasoconstrictive agent for hemostasis
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Intravenous sedatives: Propofol, remifentanil, fentanyl
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Inhalational anesthetics: Isoflurane, desflurane, sevoflurane
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Intravenous antihypertensive (nicardipine): For postoperative systolic blood pressure control
Corticosteroids
Class Summary
Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body’s immune response to diverse stimuli.
Dexamethasone (Baycadron)
Dexamethasone has many pharmacologic benefits, but also significant adverse effects. It stabilizes cell and lysosomal membranes, increases surfactant synthesis, increases serum vitamin A concentrations, and inhibits prostaglandin and proinflammatory cytokines.
Anticonvulsant Agents
Class Summary
These agents prevent seizure recurrence and terminate clinical and electrical seizure activity.
Phenytoin (Dilantin, Phenytek)
Used for seizure prophylaxis or treatment. Phenytoin works for tonic-clonic seizures and is often used because it can be administered once a day. Long-term side effects of osteopenia and cerebellar ataxia now temper its use by neurologists. This agent is one of the most difficult antiepileptic drugs to use because of its zero-order kinetics and narrow therapeutic index. In addition, it can have significant bidirectional drug interactions.
Levetiracetam (Keppra, Keppra XR)
Used for seizure prophylaxis or treatment. Administered as adjunct therapy for partial seizures and myoclonic seizures. Also indicated for primary generalized tonic-clonic seizures. Mechanism of action is unknown.
Diuretics, Osmotic Agents
Class Summary
These agents are used in an attempt to lower ICP and cerebral edema by creating an osmotic gradient across an intact blood-brain barrier; as water diffuses from the brain into the intravascular compartment, ICP decreases.
Mannitol (Osmitrol, Aridol)
Mannitol may reduce pressure within the subarachnoid space by creating an osmotic gradient between the CSF in the arachnoid space and the plasma. This agent is not for long-term use.
Antibiotics
Class Summary
Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.
Cefazolin
First-generation semisynthetic cephalosporin that, by binding to one or more penicillin-binding proteins, arrests bacterial cell wall synthesis and inhibits bacterial replication. Poor capacity to cross blood-brain barrier. Primarily active against skin flora, including S aureus. Regimens for IV and IM dosing are similar.
Clindamycin (Cleocin, Cleocin Pediatric)
A lincosamide semisynthetic antibiotic produced by 7(S)-chloro-substitution of 7(R)-hydroxyl group of parent compound lincomycin. Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Widely distributes in the body without penetration of CNS. Protein bound and excreted by liver and kidneys.
Available in parenteral form (ie, clindamycin phosphate) and oral form (ie, clindamycin hydrochloride). Oral clindamycin is absorbed rapidly and almost completely and is not appreciably altered by presence of food in stomach. Appropriate serum levels reached and sustained for at least 6 h following oral dose. No significant levels attained in cerebrospinal fluid. Also effective against aerobic and anaerobic streptococci (except enterococci).
Vancomycin
This is a potent antibiotic that is directed against gram-positive organisms and is active against enterococcal species. It is useful in septicemia and skin structure infections. Vancomycin is used in conjunction with gentamicin for prophylaxis in penicillin-allergic patients undergoing a craniotomy. Dose adjustment may be necessary in patients with renal impairment.
Local Anesthetics , Amides
Class Summary
Local anesthetic agents are used to increase patient comfort during the procedure.
Lidocaine and Epinephrine (Lignospan, Xylocaine with Epinephrine)
Lidocaine is an amide local anesthetic used in a 1%-2% concentration. This agent inhibits depolarization of type C sensory neurons by blocking sodium channels. Epinephrine prolongs the effect and enhances hemostasis (maximum epinephrine dose, 4.5-7 mg/kg).
Anesthetic Agents
Class Summary
After standard monitoring equipment is attached and peripheral venous access achieved but before the arterial line is inserted, the midazolam dose is administered. Before placement of the arterial line, it should be ensured that a radial artery graft will not be used for CABG.
Propofol (Diprivan)
Propofol is a phenolic compound unrelated to other types of anticonvulsants. It has general anesthetic properties when administered intravenously. Propofol IV produces rapid hypnosis, usually within 40 seconds. The effects are reversed within 30 minutes, following the discontinuation of infusion. Propofol has also been shown to have anticonvulsant properties.
Isoflurane (Forane, Terrell)
Isoflurane is an inhalation anesthetic. It may have a myocardial protective effect and therefore is especially useful in off-pump surgery. Isoflurane potentiates the effects of muscle relaxants. Small doses of muscle relaxants can achieve complete paralysis when administered concomitantly with isoflurane.
Desflurane (Suprane)
Desflurane is an inhalation anesthetic. It may have a myocardial protective by depressing myocardial contractility. Induces general anesthesia by enhancing inhibitory postsynaptic channel activity and inhibiting excitatory synaptic activity.
Sevoflurane (Sojourn, Ultane)
Sevoflurane is an inhalation anesthetic. May decrease blood pressure through a decrease in sympathetic activity. It may have a myocardial protective effect by depressing myocardial contractility.
Opioid Analgesics
Class Summary
Induction of anesthesia is accomplished by using high doses of opioid (usually fentanyl or remifentanil) to minimize the dose of propofol, etomidate, or thiopental and thereby maximize cardiovascular stability.
Fentanyl citrate (Duragesic, Abstral, Actiq, Fentora, Onsolis)
Fentanyl citrate is a synthetic opioid that has 75-200 times more potency and a much shorter half-life than morphine sulfate. It has fewer hypotensive effects than morphine and is safer in patients with hyperactive airway disease because of minimal or no associated histamine release. By itself, fentanyl citrate causes little cardiovascular compromise, although the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.
Fentanyl citrate is highly lipophilic and protein-bound. Prolonged exposure to it leads to accumulation of the drug in fat and delays the weaning process. Consider continuous infusion because of the medication's short half-life.
Remifentanil (Ultiva)
Remifentanil binds mu-opioid receptors at various sites within the CNS.
Antihypertensives, Other
Class Summary
Antihypertensive agents are used to reduce blood pressure.
Nicardipine (Cardene)
Nicardipine is a calcium channel blocker that has a potent and rapid onset of action, is easy to titrate, and lacks toxic metabolites. It appears to be effective in hypertensive encephalopathy, but the reported experience is limited.
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Below are five images showing how the patient's head is pinned in the Mayfield skull clamp and how the body is positioned. A) Supine with head neutral position, head pinned for a unilateral or bilateral frontal craniotomy; B) supine with head turned position, head pinned for a pterional or frontotemporal craniotomy; C) lateral position, head pinned for a suboccipital craniotomy; D) lateral position, head pinned for a more midline suboccipital craniotomy; E) semi-sitting position, head pinned for midline suboccipital craniotomy (image borrowed from Sekhar, Atlas of Neurosurgical Techniques: Brain)
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Operating room setup for a right-sided frontotemporal craniotomy. Note the location of the patient, anesthesiologist, operating neurosurgeon, and scrub tech. (image borrowed from Sekhar, Atlas of Neurosurgical Techniques: Brain)
