Interthalamic adhesion

Last revised by Joshua Yap on 13 Feb 2023

The interthalamic adhesion, or massa intermedia, is a small variably present connection between the medial apposing surfaces of the two thalami that passes through the third ventricle. It is not a commissure as once thought, as it does not contain neurons; instead, it is composed of glial tissue. Its functional significance is currently unknown 5.

If a cast is made of the ventricular system when the adhesion is present, it will create a hole (fenestration or window) in the center of the third ventricle.

The reported presence of the adhesion varies in the literature, ranging from 75% 4 to 96% 5. It has been reported to be more commonly present in females than males. Interestingly Damle et al. found that when present, the adhesion is larger in females and this correlates with increased attention 5.

Related pathology

It is larger in patients with Chiari II malformations 3.

It is suggested aberrations of the massa intermedia are associated with 6:

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Cases and figures

  • Figure 1: ventricle anatomy
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  • Case 1: breast cancer metastasis in the interthalamic adhesion
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