Temporal Horn Enlargements Predict Secondary Hydrocephalus Diagnosis Earlier than Evans' Index

Abstract

The aim of this study was to identify early radiological signs of secondary hydrocephalus. We retrieved neuroradiological data from scans performed at various times in patients who underwent surgery for secondary hydrocephalus due to severe traumatic brain injury (TBI), subarachnoid haemorrhage (SAH), or brain tumour (BT). Baseline measurements, performed on the earliest images acquired after the neurological event (T0), included Evans’ index, the distance between frontal horns, and the widths of both temporal horns. The next neuroimage that showed an increase in at least one of these four parameters—and that lead the surgeon to act—was selected as an indication of ventricular enlargement (T1). Comparisons of T0 and T1 neuroimages showed increases in Evans’ index, in the mean frontal horn distance, and in the mean right and left temporal horn widths. Interestingly, in T1 scans, mean Evans’ index scores > 0.30 were only observed in patients with BT. However, the temporal horn widths increased up to ten-fold in most patients, independent of Evans’ index scores. In conclusion temporal horn enlargements were the earliest, most sensitive findings in predicting ventricular enlargement secondary to TBI, SAH, or BT. To anticipate a secondary hydrocephalus radiological diagnosis, clinicians should measure both Evans’ index and the temporal horn widths, to avoid severe disability and poor outcome related to temporal lobe damage.

Keywords: brain; haemorrhage; hydrocephalus; injury; temporal horn; ventricular system.

Figure 1

Images of CTs and MRIs acquired at admission (T0, top row) and at the first sign of ventricular enlargement (T1, bottom row) in three patients. (A) TBI patient, (B) SAH patient, (C) BT patient. In each panel, left images show the frontal horn distances and Evans’ index measurements (white lines), and right images show the temporal horn width measurements (white lines). (A) Compared to the CT images (T0), the MRI scans after 8 weeks (T1) shows that the frontal horns enlarged from 29.1 to 39.2 mm and the Evans’ index increased from 0.22 to 0.3 (left). The right temporal horn enlarged from 1.4 to 7.7 mm and the left temporal horn enlarged from 0.9 to 7.3 mm (right). (B) T0 image is scanned after clipping a middle right cerebral artery aneurysm and performing a decompressive craniectomy for SAH. A CT image acquired 19 days after surgery (T1) shows that the frontal horn distance enlarged from 30.1 to 37.7 mm and Evans’ index increased from 0.22 to 0.28 (left). The right temporal horn width enlarged from 1.9 to 9.1 mm and the left temporal horn width enlarged from 7.7 to 8.2 mm (right). (C) T0 CT scan shows a patient with fourth ventricle lymphoma. After 3 weeks (T1), the MRI shows an enlarged frontal horn distance (from 33.6 to 43.5 mm) and an increase in Evans’ index, from 0.25 to 0.32 (left). The right temporal horn width enlarged from 1.3 to 10.9 mm and the left temporal horn width enlarged from 1.7 to 11.4 mm (right).

Figure 2

The percentage changes were greater in the right and left temporal horns (RTHW and LTHW) than in Evans’ index (EI) and the frontal horn distance (FHD).

Figure 3

Percentage changes in the Evans’ index (EI) in the three study groups. Bars indicate Standard deviations.