Diagnostic challenge of paroxysmal sympathetic hyperactivity (PSH) associated with diffuse axonal injury (DAI) in head trauma

Dear Editor it is well known that many patients show a significant altered level of consciousness after head trauma, and they subsequently present neurological sequelae, without any relevant findings in the CT scan. This is often due to the presence of diffuse axonal injury (DAI). The purpose of this study was to investigate the factors associated with DAI, especially the occurrence of paroxysmal sympathetic hyperactivity (PSH). We performed a retrospective analysis of 189 patients admitted in Intensive Care Unit (ICU) with severe traumatic brain injury, from 2008 to 2012. DAI was defined as a GCS score of 8 or less, lasting for more than 6 hours, with a normal CT or with small hemorrhages (<10 mm) in the CT and/or MRI (Chelly et al. 2011). The incidence of DAI was 28%. Factors associated with a poor prognosis were, ≥ 5 hemorrhagic millimeter lesions, lesions in corpus callosum and/or in brain stem (p = 0.004. RR: 2.40), a motor GCS ≤3 at admission (p = 0.002. RR: 1.97) and the development of paroxysmal sympathetic hyperactivity (PSH) (p = 0.007. RR: 2).These patients did not recover the level of consciousness at ICU discharge, although there was no relationship with mortality. The results of the multivariate logistic regression between risk factors and DAI, are summarized in Table 1. In this model, higher energy trauma, especially car traffic accidents and intraventricular hemorrhage were independent predictors of DAI. Epidural hematomas and subdural hematomas were “protective” factors as their presences meant a lower risk of DAI. A plausible explanation is the different mechanism of injury: extraaxial hematomas are related to trauma caused by a direct impact and axonal injury is related to acceleration and deceleration forces (Calvi et al. 2011). One of the worst outcome factors of DAI is PSH but it often remains unidentified due to the complexity of the