The "man-in-the-barrel" syndrome, first described by Sage  in 1983, is characterized by bilateral upper extremity paresis with intact motor function in the lower extremities. The patient is unable to move either arm to any stimulus, appearing as if the upper body is confined within a barrel. This syndrome typically manifests after an episode of severe hypotension causing global cerebral hypoperfusion with distal field infarctions . All previously reported cases have followed cardiopulmonary arrest or a cardiac surgical procedure. This report describes a case of man-in-the-barrel syndrome after uneventful endoscopic sinus surgery.
A 58-yr-old woman with insulin-dependent diabetes mellitus, hypercholesterolemia, and hypothyroidism presented for endoscopic maxillary sinus surgery. Her medications included insulin, thyroid hormone, and lovastatin, and she reported no allergies. The patient specifically denied any history of hypertension, angina, dyspnea, or orthopnea and stated that a stress test performed the previous year was normal. Physical examination was unremarkable, and her preoperative blood pressure was 130/70 mm Hg.
After the patient received IV midazolam preoperatively, anesthesia was induced with propofol, fentanyl, and pancuronium IV. Endotracheal intubation proceeded without difficulty, and the nasopharynx was topicalized by the surgeon with 4% cocaine. The blood pressure and heart rate subsequently increased to 190/95 mm Hg and 125 bpm, respectively. Esmolol 30 mg IV was administered, the blood pressure and heart rate stabilized to 125/85 mm Hg and 80 bpm, respectively, and anesthesia was maintained with isoflurane and nitrous oxide. A short time later, the patient developed decreased blood pressure with values between 79/45 and 85/42 mm Hg over a 5-min interval. A fluid bolus of 500 mL of lactated Ringer's solution was given, the isoflurane concentration was decreased, and the blood pressure returned to baseline levels. The remaining intraoperative course was uneventful, with blood pressures ranging from 100/60 to 135/70 mm Hg.
At the end of the procedure, isoflurane and nitrous oxide were discontinued, and paralysis was reversed with IV neostigmine. Spontaneous ventilation returned with adequate tidal volumes, and the patient was able to strongly move her feet on command and to sustain a 5-s head lift; however, no hand or arm movement was evident. She was successfully tracheally extubated and confirmed that she could not move either arm. In the recovery room, physical examination revealed bilateral upper extremity flaccid paralysis but intact deep tendon reflexes, proprioception, and sensation. Episodes of hypertension were treated with IV labetalol; 3 h after surgery, she was able to move her distal upper extremities slightly but was still unable to lift them against gravity. Emergency neurosurgical evaluation confirmed these physical findings and led to the diagnosis of man-in-the-barrel syndrome.
At this point, the patient complained of new-onset chest pain and nausea. An electrocardiogram showed questionable ST segment depression in leads V1 to V5, which had not been present on the preoperative electrocardiogram, and a chest film revealed no abnormality. Nitroglycerin was administered, and the patient was transferred to the coronary care unit. Over the next 24 h, the upper extremity weakness improved significantly, and the patient was able to lift both arms against gravity and had full functional use of both hands. Myocardial infarction was ruled out on the basis of cardiac enzymes, specifically myocardial-specific creatine kinase and lactic dehydrogenase; on the second postoperative day, a persantine thallium stress test revealed no reversible defects. A magnetic resonance imaging examination of the brain, brainstem, and cervical and thoracic spine areas obtained on the third postoperative day revealed no abnormalities. All neurologic deficits were completely resolved at that time.
On the fourth postoperative day, the patient had diabetic ketoacidosis with a glucose level >700 mg/dL. Arterial pH was 7.05 and the potassium level was 7.5 mEq/L. This was successfully treated with IV insulin and hydration, but 2 days later, the patient developed an acute myocardial infarction. Echocardiography demonstrated an estimated ejection fraction of 30% with akinesis of the entire anteroseptal and apical walls, as well as hypokinesis of the mid-lateral wall. Cardiac catheterization identified severe two-vessel disease, and on Postoperative Day 10, the patient underwent uncomplicated coronary artery bypass grafting (CABG). Mean arterial pressures during cardiopulmonary bypass were maintained >60 mm Hg, and recovery was unremarkable, with no abnormal neurologic findings noted postoperatively. Two weeks after endoscopic maxillary sinus surgery, the patient was discharged home without any residual neurologic deficit.
Our patient represents the first reported case of man-in-the-barrel syndrome after noncardiac surgery and in the absence of profound hypotension. All previously documented cases [1-6] have followed either cardiopulmonary arrest or cardiac surgical procedures and are believed to be the result of distal field cerebral infarctions. Distal field cerebral infarctions are localized to the border zone areas of the brain, in which terminal arteriolar anastomoses occur between the major cerebral arteries. These are also known as watershed or border zone infarctions and usually are associated with global cerebral hypoperfusion . Angiographic data have shown that, even under normal conditions, circulation in these areas can vary, with periods of stasis frequently occurring [2,8]. When exposed to hypotension, these border zone territories are highly susceptible to ischemia and infarction . The region most vulnerable to watershed infarction is the border zone between the anterior cerebral artery (ACA), the middle cerebral artery (MCA), and the posterior cerebral artery. This area is located at the occipitoparietal convexity, where infarctions produce deficits, such as visual field defects, cortical blindness, saccadic gaze palsy and homonymous hemianopsia [7,9].
The border zone between the ACA and the MCA crosses the middle frontal gyrus, the precentral and postcentral gyri, and the parietal lobe, and in its path traverses the motor homunculus of the upper extremities. It is not as susceptible to watershed infarction as the occipitoparietal border zone region, but when hypoperfusion occurs, bibrachial paresis can result [7,9]. The area least susceptible to distal field infarction is the border zone between the posterior cerebral artery and the MCA, which is located close to the occipital pole and along the inferolateral border of the temporal lobe. Infarctions there result in speech impairments [7,9]. Border zone infarctions have been reported since the early 1900s, but the man-in-the barrel syndrome was not described until 1983 [1,2,10]. Sage  coined the term to explain the clinical picture that results from watershed ischemia or infarction of the border zone area between the ACA and the MCA after a period of global cerebral hypoperfusion. Patients with this syndrome experience bilateral brachial paresis with intact motor function of the lower extremities. Brainstem reflexes are intact and deep tendon reflexes are normal. If patients are alert and cooperative, an examination reveals normal sensation, proprioception, and speech and facial movements, although they cannot move their arms to any stimulus, as if their upper body is confined in a barrel [1,3,4].
In a series of 28 comatose patients who had experienced severe hypotension with systolic blood pressures <50 mm Hg, 9 (32%) showed evidence of man-in-the-barrel syndrome . These patients moved both lower extremities either spontaneously or in response to pain but did not demonstrate any upper extremity movement. An autopsy of one of these patients confirmed a distal field infarction in the territory of the MCA. Eight of the nine patients who exhibited the syndrome died .
A subsequent series of 34 comatose patients who experienced periods of hypotension with systolic blood pressures <50 mm Hg for >or=to5 min was reported by Sage and VanUitert . Of the 34 patients, 11 (32%) demonstrated man-in-the-barrel syndrome, and only 1 patient survived with complete resolution of neurologic findings. Of the 11 patients who developed bilateral brachial paresis, computerized tomographic examination of the brain was normal in 6, as it was in our patient .
More recently, Shaw et al.  reported a case of man-in-the-barrel syndrome after an emergent CABG procedure after an episode of cardiac arrest and resulting in death 4 wk postoperatively without improvement in the bilateral brachial paresis. In contrast, Olejniczak et al.  and Hurley and Wood  have described isolated cases of man-in-the-barrel syndrome after emergent CABG procedures with cardiopulmonary bypass but without any hypotensive episodes or cardiopulmonary arrest. Olejniczak et al.'s patient underwent a computed tomography scan on Postoperative Day 3, which showed possible hypodensities bilaterally, but the examination was limited due to artifact. A magnetic resonance imaging scan was performed for Hurley and Wood's patient on Postoperative Day 6 and demonstrated border zone infarctions. Both patients recovered full function of their upper extremities, and each patient was discharged home without further complications [4,6].
Our case, in conjunction with those reported by Olejniczak et al. and Hurley and Wood, suggests that full recovery of neurologic function in man-in-the-barrel syndrome is possible, and that significant ischemia to border zone areas of the brain may be reversible. The exact mechanism for this is unclear and the extent of ischemia or infarction necessary to produce this syndrome is also unknown, but it has been suggested that a sudden onset of hypotension is the precipitating event [1,3]. Although the development of man-in-the-barrel syndrome indicates a poor prognosis for survival [1,3], our case and two others [4,6] suggest that mild forms of cerebral hypoperfusion may be associated with reversible manifestations of this syndrome. When cerebral perfusion pressure was meticulously maintained (as it was during the subsequent CABG procedure), no manifestations of man-in-the-barrel syndrome were observed.
Development of bilateral brachial paresis after cerebral hypoperfusion is not predictable, and risk factors are not clinically identifiable. Imaging studies are also unreliable in establishing the diagnosis. Nonetheless, our case illustrates the reversibility of border zone ischemia and suggests that even mild hypotension for a brief period may be significant enough to produce man-in-the-barrel syndrome in susceptible individuals undergoing otherwise clinically uneventful noncardiac surgery.
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