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What happened to my foot?: Amnesia following surgery

AORN Journal, Jan, 2008 by Nancy J. Girard

Mrs X, a 64-year-old woman, underwent orthopedic reconstruction of her foot as elective ambulatory surgery. She had no significant medical history and no past surgical history. Mrs X takes rabeprazole, a proton pump inhibitor, to treat gastroesophageal reflux disease. The only other medications she takes are multivitamins and glucosamine with chondroitin. All her laboratory and diagnostic preoperative studies were within normal range.

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Because of the extensive surgery needed, Mrs X received general anesthesia. The surgery went well with no complications. Postoperatively, Mrs X was given morphine sulfate intravenously for pain. She experienced postoperative nausea and vomiting that was not controlled with the routine IV medications, so oral metoclopramide was administered with good results. Mrs X was discharged to home with prescriptions for a narcotic analgesic (ie, hydrocodone) to be used as needed for pain and metoclopramide to be used as needed for nausea and vomiting.

Mrs X's recovery progressed without incident, and she discontinued self-administration of pain and anti-emetic medications on postoperative day two. On the third postoperative day, Mrs X ate breakfast and again became nauseated. After she experienced intense retching and vomiting, her husband helped her back to bed. At that point, she looked at her foot and asked her husband what had happened to it. She repeated this question over and over and appeared to have no memory of the surgery.

Mrs X's frightened husband rushed her back to the hospital where she was admitted with a tentative diagnosis of stroke or a transient ischemic attack. By the afternoon of the day of admission, Mrs X was alert, cognitively intact, and thinking clearly, and her memory of the surgery was returning. Magnetic resonance imaging, computed axial tomography scans, and electroencephalogram showed no pathology. All diagnostic test results showed no associated pathology or neurological abnormalities.

A month after surgery, Mrs X was healing nicely with no recurrences of amnesia and no residual neurological effects. Because there was no identified pathology determined to cause the amnesia, the final diagnosis was either acute postoperative drug-induced amnesia or transient global amnesia (TGA).

Discussion

Amnesia that occurs after surgery should not be confused with delirium or dementia. Nurses should be astute in assessing patients' preoperative and postoperative cognitive and neurological status so that an accurate diagnosis can be made and effective treatment can be given if changes are perceived. Postoperative drug-induced delirium has additional cognitive symptoms and can include the inability to concentrate, confusion, disorganized thinking, and disorientation to time or place. Mrs X had little experience with medication and none with anesthesia. The combination of general anesthesia, pain medication, and anti-emetic agents could have caused the amnesia; however, this incident occurred on the third postoperative day after the medications had been discontinued.

Transient global amnesia is the brief inability to recall past memories despite normal neurological functioning. This most often happens to women between the ages of 50 and 60 years. (1) The patient often exhibits repetitive questioning (ie, "What happened to my foot? What happened to my foot?"). The loss of memory typically lasts from 30 minutes to 24 hours (2) and usually happens during the immediate postoperative recovery time. There are only a few incidents of TGA after general anesthesia reported in the literature, (2,3) and anesthesia does not appear to be a direct trigger.

Thorough neurological diagnostics should be completed because TGA mimics an acute cerebral ischemic event. Transient global amnesia is poorly understood and its etiology unknown. One postulation is that Valsalva-tike activities may be a cause, with rapid venous flows into the cerebral venous system producing temporary ischemia in portions of the brain. Mrs X had strenuous gagging and vomiting immediately before developing amnesia, which could have signaled a Valsalva-like event leading to the amnesia. It is unlikely that Mrs X will have a recurrence of this benign clinical event.

Perioperative Points

* Assess and document cognitive status preoperatively.

* Before surgery, discuss the potential for temporary postoperative confusion with patients and their family members.

* Postoperatively, assess cognitive status and compare this assessment with preoperative findings, document any changes, and alert physicians of any unexpected changes.

* Include written discharge instructions describing what family members or home caregivers should do if the patient experiences sudden changes in mental awareness.

References

(1.) Miller JW, Petersen RC, Metter EJ, Millikan CH, Yanagihara T. Transient global amnesia: clinical characteristics and prognosis. Neurology. 1987;37(5): 733-737.

(2.) Bortolon RJ, Weglinski MR, and Sprung J. Transient global amnesia after general anesthesia. Anesth Analg. 2005;101(3):916-919.

Health Care Industry

What happened to my foot?: Amnesia following surgery

AORN Journal, Jan, 2008 by Nancy J. Girard

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