Case 9 6 2 Case discussion The onset of progressive lethargy over a period of days, slurred speech and the weakness indicates a lesion of the central nervous system. Given the progression of lethargy, the fever and the absence of acute onset, an infectious origin seemed more likely. This was suggested by the CSF examination, showing an elevated cell count, especially lymphocytes. The differential diagnosis consisted of (viral) meningo-encephalitis – most likely caused by enteroviruses, arboviruses or herpesviruses – neuroborelliosis and vasculitis. Antibiotics and antiviral drugs were started. Case 1 Fig. 1 a–c a b c c–e  Case discussion On ICU admission the main medical problems were (1) respiratory insufficiency requiring mechanical ventilation, (2) progressive loss of consciousness and (3) the unknown origin of the coma. Maintenance of an adequate airway and concomitant aspiration pneumonia necessitated mechanical ventilation. There are numerous possible causes of progressive loss of consciousness, including cerebrovascular accidents, cerebral infections (viral, bacterial, parasites, tuberculosis, Lyme disease), neoplastic and auto-immune diseases (sarcoidosis, vasculitis, SLE). Despite the elevated white cell count and the presence of protein in the CSF, no infectious origin was determined. Screening for HIV and coagulation disorders was negative. Repeated blood and CSF cultures were negative, and there was no response after 14 days of ceftriaxone and acyclovir. Nevertheless CSF analysis after treatment was interpreted cautiously. Many viruses responsible for meningo-encephalitis cannot be identified using common tests. MRI showed multiple hyperintense brain lesions, especially of the brainstem. Because of the massive involvement of the brainstem and persistence of coma for 2 weeks, the prognosis was considered poor. Case 1 Case discussion Elevated pressure, white cell count and protein level in the CSF in combination with the extensive white matter lesions confirmed the diagnosis of ADEM. ADEM is a rare cause of prolonged coma with complete recovery under specific treatment, and intensivists should be aware of this disease. Withdrawal or withholding of care in patients with prolonged coma can hardly be discussed as long as the cause of the coma remains unknown and the prognosis cannot be accurately established. Treatment with intravenous corticosteroids resulted in a full recovery. The absence of a previous infection is a peculiar aspect of our case. Comments 1 2 3 4 5 3 4 5 3 4 5 4 5 6 7 8 9 10 In conclusion, treatment of coma should be continued when the cause of the coma is unclear, even if there are numerous lesions in the brain. ADEM should be considered in comatose patients with raised CSF pressure, protein and lymphocytes, negative CSF cultures, and multiple white matter lesions on cerebral MRI. ADEM is predominantly seen in children, but also occurs in adults. Recovery may last weeks.