Neuropsychological deficits of a U.S. Army pilot following an anoxic event as a function of cardiac arrest

Military Medicine, Sep 2003 by Baggett, Mark R, Kelly, Mark P, Korenman, Lisa M, Ryan, Laurie M

Anoxic encephalopathy occurs as a result of cardiac arrest, respiratory distress, or carbon monoxide poisoning. This is a case report on the neuropsychological deficits of anoxia in an otherwise previously healthy 36-year-old male pilot. The patient was taking an over-the-counter supplement that included an herb called Ma Huang on the day of his cardiac arrest. Ma Huang is reported to potentially present an increased risk of cardiac infarctions and central nervous system dysfunctions. Several instances of death have been linked to Ma Huang. The patient produced a neuropsychological profile that evidenced impairments in executive functioning, memory, language, attention, intellectual and academic functioning, as well as motor speed and coordination, all of which are consistent with diffuse brain damage. This case adds to the body of literature documenting the physical and neuropsychological effects of anoxia, as well as the effects of ephedrine-based supplements, such as Ma Huang.

Introduction

When oxygen saturation is depleted for 5 minutes or more, permanent brain damage occurs as a result of an accumulation of pathological excitatory neurotransmitters or lactic acid.1 Oxygen insufficiency quickly produces severe neuronal damage, and anoxia can produce devastating and widespread effects on the brain. Anoxia can result in extensive cerebral and cerebellar brain damage as well as a variety of cognitive, perceptual, and motor abnormalities. However, because the medial temporal lobes are particularly sensitive to oxygen deprivation, anoxia may result in circumscribed amnesia. Area CA1 of the hippocampus has been identified as particularly sensitive to the effects of anoxia.2

At the time of anoxia, the patient was taking a dietary supplement containing the ingredient Ma Huang. Ma Huang is an ephedrine-based supplement that acts as a nervous system stimulant. Products containing ephedrine have been known to cause vasoconstriction and cardiac stimulation, which, in turn, stimulates an acute increase in blood pressure, heart rate, mydriasis, insomnia, vertigo, headaches, and nervousness.3 One study stated that approximately 926 cases of possible Ma Huang toxicity were reported to the Food and Drug Administration between the years of 1995 and 1997. Of those cases, 37 were cardiovascular events, 11 resulted in sudden death, 16 were strokes (3 of which resulted in death), and 10 myocardial infarctions.4 Additional evidence of adverse health consequences that are attributable to ephedrine include reports of central nervous system insult, including stroke and seizures, as well as reports of psychiatric complications.5,6 Thus, there appears to be a large body of evidence developing, all of which point to the dangers involved with using ephedrine-based supplements.

Case Reports

A 36-year-old male Army Captain suffered a cardiac arrest while running in the 2-mile run portion of the U.S. Army physical fitness test. The patient was in full arrest for 8 minutes prior to the arrival of military medical personnel, when he was successfully defibrillated and stabilized for transport to a nearby Army hospital. On the same day, the patient was transferred to Walter Reed Army Medical Center where it was determined that he suffered from an anoxic event due to insufficient oxygen to the brain. Preliminary neuroimaging results, including magnetic resonance imaging and computerized tomography scans, showed no abnormalities.

It was revealed by the patient that on the day of his heart attack, and for 2 weeks before, he had been taking an over-the-counter dietary supplement. Included in this supplement was the ingredient Ma Huang, an herb proposed to promote weight loss and increase metabolism. He reported that he was taking two tablets 3 times per day as recommended on the label of the supplement. One month after the injury, the patient was transferred to a rehabilitation center in Virginia. At this facility, he attended a 5-day per week rehabilitation program that included occupational and speech therapies.

During a neuropsychological evaluation conducted 9 months after injury, the patient reported problems with memory, concentration, and problem-solving ability. The patient's spouse stated that there had been some improvement observed since the time of the injury. He also reported low frustration tolerance and described having arguments with his wife more frequently since the accident. Neuropsychological evaluation of this patient included Weschler Adult Intelligence Scale-Revised, Wide Range Achievement Test 3, Finger Tapping Test, Strength of Grip, Seashore Rhythm Test, Auditory Consonant Trigrams, Trail Making Test (A & B), Boston Naming Test, Thurstone Verbal Fluency Test, Rey-Osterreith Complex Figure, Wechsler Memory ScaleRevised, California Verbal Learning Test, Wisconsin Card Sorting Test, Automated Neuropsychological Assessment Metrics,7 Minnesota Multiphasic Personality Inventory-2, and Portland Digit Recognition Test. The patient's medical history contained no indications of heart disease or previous neuropsychological impairment. Results of neuropsychological tests are presented in Table I.