[Study of the diameter of the third ventricle with transcranial sonography]

Transtemporal insonation by means of transcranial color-coded duplex sonography (TCDS) with low frequency probes (2-2.5 MHz) makes it possible to not only evaluate the blood vessels of the circle of Willis but also of brain parenchymal structures. A reduced number of studies, none of them in our area, have reported its usefulness for the evaluation of the ventricular system in adults. Aim. To evaluate ability of the transcranial duplex to measure the third ventricle diameter in a sample of patients with different neurological illnesses.

Patients of all ages admitted to our neurology ward and whose diagnostic procedure included a brain magnetic resonance (MRI) were recruited. The largest third ventricle diameter was measured with both the TCDS and MRI in axial planes. We report the results observed with both techniques and the lineal correlation between both of them.

We included 30 patients with mean age 48.5 years and 66.6% females. The third ventricle diameter (average +/- standard deviation) was 3.97 +/- 2.58 mm as measured with TCDS and 3.70 +/- 2.27 mm on MRI. Linear correlation between the values observed was high (r=0.85).

Transcranial duplex is a cheap, safe and easy to perform technique. It has similar results in comparison with those obtained with the MRI when the third ventricle size is measured.