Transient Global Amnesia After Endoscopic Septoplasty and Turbinate Reduction

While nasal complications of endoscopic septal and turbinate surgery have been documented, cognitive complications after surgery are rare. We report an unusual case of postoperative transient global amnesia (TGA) after endoscopic nasal airway surgery performed under general anesthesia. A middle-aged patient had complete loss of memory after a routine endoscopic septoplasty and inferior turbinate reduction, but regained full function prior to discharge. The patient was a 59-year-old Asian male with nasal obstruction, obstructive sleep apnea, and poor tolerance of continuous positive airway pressure despite medical therapy with a broad leftward septal deviation and bilateral inferior turbinate hypertrophy. The patient had an extensive cardiac history to include dilated cardiomyopathy, atrial flutter, and heart block with a cardiac resynchronization therapy defibrillator. The patient had received general anesthesia once and sedation under monitored anesthesia care multiple times without complication. The patient underwent an uneventful endoscopic septoplasty and bilateral inferior turbinate submucous reduction. During induction and throughout the case, the patient received propofol, remifentanil, and rocuronium intraoperatively for a case duration of 1 hour and 45 minutes. There were no blood pressure or heart rate abnormalities during the procedure and blood loss was minimal. There were no significant periods of hypotension during induction or throughout the case. After uneventful extubation, the patient was transported to the postanesthesia recovery unit, still in the process of fully waking up from anesthesia. Thirty minutes after surgery, he was noted to be confused with no recollection of the year, the president, or his age. The patient could not recall getting to the hospital or undergoing surgery. His memory of personal historical details remained intact, and he could report his birth date, recognize his spouse, and discuss his medical history. The neurology service was consulted and during the neurological evaluation, the patient was oriented only to himself. While he could immediately recall words, he scored 0/3 on delayed recall of words, even with multiple choice. The patient was otherwise neurologically intact with no focal deficits. The patient was diagnosed with TGA and was admitted. Due to our patient's complex cardiac history, additional imaging was recommended. A noncontrast head computed tomography was performed, with no significant abnormalities noted, including acute hemorrhage, infarction, or mass. A magnetic resonance imaging was not performed due to pacemaker incompatibility. Labs, including HbA1c, lipid panel, complete blood count, and basic metabolic panel were within normal limits. The patient started to become more alert and aware, retaining information of events occurring in the hospital 7 hours after the onset, and the amnesia resolved by the following day. After 16 hours of observation, he could recall 2/3 of words on delayed recall and was oriented to person, place, time, and situation. He continued to have retrograde amnesia limited to events on the day before surgery and the day of surgery prior to going to the operating room. He was discharged and made a full recovery. Overall, TGA is a rare phenomenon with sudden loss of memory that completely resolves. It is uncommon but reported with an estimated incidence of 3 to 8 per 100,000.1 During TGA, patients experience transient anterograde amnesia as well as retrograde amnesia. Criteria for TGA include acute new memory impairment with resolution within 24 hours of onset, no other focal neurological deficits, no preceding head trauma or epilepsy, and intact consciousness and orientation to self.1 TGA is a primarily clinical diagnosis and does not require imaging unless atypical signs exist. The pathophysiology of TGA remains unknown, with theories ranging from ischemic stroke to cerebrovascular congestion to psychogenic origins. Often, episodes have an inciting physical or mental trigger. There are some reports of TGA after general anesthesia, gastrointestinal endoscopy, cardiac catheterization, and neurointerventional procedures. Stenosis or compression of the internal jugular vein may cause venous outflow obstruction, influencing the development of the condition.2 Rarely, there can be isolated ischemic strokes of the hippocampus.1 A strong association with migraines has been reported, increasing the risk of TGA by 6 times.3 Ischemic heart disease and hyperlipidemia could also be risk factors for TGA.4 Like Takutsubo's cardiomyopathy, where a catecholamine surge may trigger a receptor cascade resulting in myocardial stunning, a parallel mechanism may occur in the brain.5 The exact cause for TGA in this patient is unknown, but likely triggered by surgery or general anesthesia and predisposed by the patient's hyperlipidemia. Patients without focal deficits and acute development of amnesia consistent with TGA are managed with supportive care until symptoms resolve. The prognosis of this condition is good with a resolution by 24 hours. Most patients do not face any long-term complications of TGA, but some limited studies suggest that for a subset of patients, there may be an association with an increased risk of developing epilepsy. Additionally, up to 15% of patients may have a recurrence of TGA in the future.1 TGA after endoscopic septoplasty and turbinate reduction is an acute change that can raise concern for cerebrovascular ischemia. However, it is a self-resolving condition that is benign and incompletely understood. A complete neurological evaluation and imaging may be recommended due to comorbid conditions or atypical features on presentation. Arifeen S. Rahman, conceptualization, data gathering, manuscript writing; Peter H. Hwang, conceptualization, manuscript writing; David T. Liu, conceptualization, data gathering, manuscript writing. Peter H. Hwang, MD, has the following disclosures, none relevant. Consultant: Medtronic, Stryker, ClaraSim. Equity ownership: SoundHealth. Arifeen S. Rahman, MD, has the following disclosures, none relevant. Consultant: SoundHealth. None.