Neurologic and psychiatric complications are often encountered in the postoperative period and may be very alarming. Hospitalists must be able to recognize and initiate treatment for many of these postoperative complications. The differential diagnosis of common problems (such as headache) may also be very different in the perioperative period. This chapter will cover common presentations, risk factors and prevention techniques, and management of several postoperative neurologic and psychiatric conditions, including: seizures, delirium, confusion, delayed emergence, muscle weakness by anesthetic drugs, stroke, blindness, awareness under anesthesia, cognitive dysfunction, headache, spinal cord injury, and peripheral nerve injury.
Seizures in the postoperative are generally rare but require immediate treatment. Dangers of seizures include hypoventilation, hypoxemia, musculoskeletal injury, aspiration, and death.
There are many different causes of seizures in the perioperative period, including hypoglycemia from prolonged NPO status, local anesthetic systemic toxicity (LAST) from intravascular injection of local anesthetic such as bupivacaine, and electrolyte abnormalities. Patients with intracranial structural lesions, patients having intracranial surgery, and patients with traumatic brain injury (TBI) are also at risk for seizures.
Most anesthetics drugs are antiepileptic. However, some anesthetic drugs can induce seizure foci or at least cause changes in the EEG while infusing. These include ketamine, methohexital, and meperidine. Of note, methohexital and etomidate are often used as general anesthesia on patients prior to electroconvulsive therapy (ECT) where a seizure is purposely induced.
Stopping the seizure is the initial and most important treatment. Airway management and protecting against head or body injuries is also important. Pharmacologic adult intravenous therapy includes benzodiazepines such as midazolam 1 to 5 mg, diazepam 5 to 10 mg, propofol 50 to 100 mg, and phenytoin 500 to 1000 mg (infused slowly). If LAST is the cause, Intralipid (20% fat emulsion) bolus 1.5 mL/kg over 1 minute (about 100 cc) followed by continuous infusion of 0.25/kg/min is the treatment.
In patients who have had a peripheral nerve block or who have a continuous nerve catheter for pain management, LAST as the cause of seizure must be considered.
Intralipid 20% therapy is used to treat LAST.
Electrolyte abnormalities and hypoglycemia must be corrected in the treatment of seizures. Sodium abnormalities leading to seizures are most common in neurosurgical patients, and are most often seen in conjunction with the Syndrome of Inappropriate Antidiuretic Hormone (SIADH), Diabetes Insipidus (DI), or due to hypertonic therapy to treat increased intracranial pressures. Seizures can present in any of those conditions but are more likely when sodium levels are <120 mM or >158 mM.
Management includes ruling out other conditions that are not seizures. If it is unclear if seizure activity is present, an electroencephalogram (EEG) should be obtained in consultation with neurology. Pseudoseizures or psychogenic non epileptic seizures ...