Intravenous hypertonic fluid therapy has been proposed to improve secondary ischemic injury after cerebrospinal trauma. We report the case of a 14-year-old boy with vasospasm of the intracranial vertebral arteries and ischemic brain stem damage following head trauma. The patient presented with severe tetraparesis and somatosensory (SSEPs) and brain stem auditory evoked potentials (BAEPs) impairment. The patient was treated with two subsequent hypertonic saline (HS) infusions, 2.7% and 5.4%, respectively, for a period of 48 sp, followed by standard hypervolemic therapy. After the first treatment with 2.7% HS, improvement of SSEPs without neurological improvement was apparent. Relative hypervolemia was subsequently maintained by administration of crystalloids and 20% albumin for 48 h. During standard hypervolemic therapy, no clinical and/or electrophysiological change occurred. The second infusion of 5.4% HS was concomitant with further amelioration of SSEPs and improvement of motor performance. Twelve hours after the second HS infusion, the neurological status returned to preinfusion levels, while SSEPs showed no further changes. BAEPs never changed during fluid therapy. No complication occurred secondary to the infusion of HS. This case report suggests that local improvement of brain stem perfusion following hypertonic fluid therapy accounts for or relevantly contributes to the neurological and SSEPs improvement of the patient.