Radiological signs of the syndrome of the trephined

Abstract

Introduction: Syndrome of the trephined (ST) is a post-craniectomy complication. It is characterized by the appearance of new neurological symptoms following the craniectomy, which are relieved after cranioplasty. The purpose of our work was to identify radiological signs and imaging biomarkers of the ST.

Methods: CT images of 32 patients were retrospectively analyzed (ST = 13, controls = 19). While the shapes of craniectomy flap were qualitatively assessed, deviation of the midline structures, relative intracranial cerebrospinal fluid (CSF) volume, and the 3rd ventricle's volume were quantitatively measured.

Results: We did not find between-group differences in the mean age or number of post-craniectomy days. ST was diagnosed during the second post-craniectomy month. The occurrence of a sunken skin flap sign was similar in both groups (69.23 % in ST group, 57.89 % in control group). Occurrence of paradoxical herniation and deviation of the midline structures were not significantly different between groups. Mean relative intracranial CSF volume was significantly smaller in ST patients (ST = 5.59 %, controls = 8.12 %, p = 0.01). ST patients, compared to controls, had also significantly smaller mean 3rd ventricle volumes (ST = 1748 mm(3), controls = 2772.97 mm(3), p = 0.03).

Conclusions: ST is an infrequent and delayed post-craniectomy complication. The most common radiological findings (paradoxical herniation, deviation of the midline structures, and sunken skin flap sign) might not be specific for ST. Significantly lower 3rd ventricle, and relative intracranial CSF volumes, suggest that altered biophysical CSF properties underlie ST pathophysiology. Therefore, volume measurements of 3rd ventricle could be useful for identification of patients who have higher probability of developing the ST.

Keywords: CSF; Decompressive craniectomy; Sinking skin flap syndrome; Syndrome of the trephined.