Deep coma and diffuse white matter abnormalities caused by sepsis-associated encephalopathy

Abstract

In January, 2012, a 53-year-old woman with a history of progressive polyposis coli and hypertension was admitted to the intensive care unit (ICU) of our hospital because of septic shock 4 days after laparoscopic subtotal colectomy. She was intubated and mechanically ventilated, underwent emergent re-laparotomy for anastomotic leakage, and was treated with antibiotics. Blood cultures were positive for multiresistant Enterococcus faecium. After re-laparotomy the patient was sedated with midazolam for 2 days. The neurologist was consulted on the fourth postoperative day because of the patient’s persistent low level of consciousness. On neurological examination, we found no eye opening or motor response to a painful stimulus, intact brainstem refl exes, and generalised arefl exia of arms and legs with indiff erent plantar refl exes. We observed no signs indicative of minimally convulsive status epilepticus. During the period of septic shock and surgery, blood pressure had not been lower than 100/50 mm Hg and laboratory tests did not show abnormalities that could explain the patient’s coma. Non-contrast CT (NCCT) of the brain showed abnormal hypodensity of the complete white matter with swelling of the entire brain (fi gure); CT angiography was normal. Electromyography showed absence of motor unit potentials in arm and leg muscles without evidence for accompanying neuropathy. We made a diagnosis of sepsis-associated encephalopathy and critical illness myopathy. Because of the deep coma and the diff use and severely abnormal aspect of the white matter—both associated with poor outcome—dis continuation of treatment was discussed, but we recommended to continue treatment. On the ninth postoperative day the patient opened her eyes in response to painful stimuli, but there was still no motor response. Follow-up NCCT showed no improvement of the white matter abnormalities. In the following weeks the condition of the patient gradually improved and 4 weeks after the re-laparotomy she had regained full consciousness. When the patient was discharged from the ICU her muscle strength had gradually improved with movements against gravity now possible. At that time brain MRI was normal except for a small number of white matter lesions (fi gure). The patient was transferred to a rehabilitation centre 6 weeks after the initial onset of septic shock. At that point she was able to walk short distances. At last follow-up on Aug 19, 2012, she had regained independence in activities of daily living and was living at home. Sepsis-associated encephalopathy is a severe complication of sepsis and is associated with poor outcome. The reported incidence ranges from 9% to 71% because of variations in the defi nition. A recent study in an ICU showed that patients with sepsis secondary to intestinal infections are prone to develop septic encephalopathy, with Escherichia coli and Enterococcus faecium among the most frequently cultured bacteria. The exact pathogenesis of sepsis-associated encephalopathy remains unclear; disruption of the blood-brain barrier and mitochondrial dysfunction are probably involved. Imaging of the brain can show atrophy and periventricular white matter lesions. The diff use and severe white matter abnormalities like those we observed in our patient are rare and have been associated with poor outcome. This case shows that severe encephalopathy with extensive white matter lesions can be a reversible condition. Clinicians should realise that the fi rst signs of improvement of the clinical condition could still be observed beyond 7 days after onset.