Median-evoked somatosensory potentials in severe brain injury: does initial loss of cortical potentials exclude recovery?

OBJECTIVE: In patients with severe brain injury (SBI) median-evoked somatosensory potentials (M-SSEP) serve as a prognostic tool. Bilateral loss of cortical responses (BLCR) is usually thought to be a reliable marker of poor prognosis. Prognostic accuracy to predict a poor outcome depends on the cause of coma and is best in hypoxic-ischemic encephalopathy (HIE) reaching almost 100% which is in contrast to patients with other etiologies of coma, especially traumatic brain injury (TBI). Only little evidence exists on the possibility of electrophysiological recovery of BLCR in repeated or serial SSEP-examinations and detailed functional outcome in these cases. METHODS: 28 patients (78.6% male, 21.4% female, mean age 43.1±18.6 years) from our in-patient early (post-acute) neurorehabilitation center with BLCR in their first M-SSEP were re-examined after a mean interval of 66±55.8 days. SBI was caused by different etiologies. We retrospectively analyzed (a) the recovery rate from BLCR in consecutive M-SSEP and (b) the detailed functional outcome of those patients with recovered cortical responses. RESULTS: 14/28 (50%) patients with primarily BLCR showed re-occurrence of cortical potentials, either uni- or bilaterally. Of the 14 patients, one died due to a non-neurological cause. Of the remaining 13 patients 6 - most of them suffering from traumatic brain injury (TBI) - could be transferred to further continuing neurorehabilitation and achieved good functional long-term outcome. BLCR in HIE still had a poor prognosis with none of our patients achieving an outcome better than vegetative state. CONCLUSIONS: Electrophysiological recovery from primarily BLCR seems possible and is accompanied by good functional outcome in a relevant number of patients. Thus caution is warranted in predicting a poor prognosis based predominantly on SSEP, especially in patients with TBI. Focusing SSEP-examination on the early days after severe brain injury and performing only one examination in the case of BLCR may lead to systematic underestimation of the possibility of recovery.

Critical-illness-polyneuropathy as sequelae of severe neurological illness: incidence and impact on ventilator therapy and rehabilitation.

INTRODUCTION: Critical-Illness-Polyneuropathy (CIP) is common in critically ill patients. In contrast to CIP arousing from primary non-neurological causes, studies dealing with CIP following a primary neurological illness are rare. This mono-center, retrospective study was performed to examine a) the incidence of CIP in patients after severe neurological illnesses and b) the impact on ventilator therapy. MATERIAL AND METHODS: Retrospective analysis of all patients, admitted for early (post-acute) neurological rehabilitation following severe neurological diseases between 01.01.2006 and 31.12.2010. Patients routinely underwent standard electrophysiological evaluation (nerve conduction studies of 8 motor and 6 sensory nerves; needle electromyography of 6 muscles). Diagnosis of CIP required a) pathological spontaneous activity in at least two muscles and b) reduced compound muscle activity potentials (CMAP) in at least two motor nerves of different extremities. RESULTS: CIP was diagnosed in 430 of 623 patients (69.0%). Patients with proven CIP required significantly (p < 0.001) longer ventilator therapy (33.1 days) in contrast to patients without CIP (21.5 days). CONCLUSION: CIP is common in patients suffering from primary severe neurological diseases. Due to CIP, duration of ventilator therapy is significantly prolonged. In patients with severe neurological diseases electrophysiology is crucial to establish the correct diagnosis.