Subfalcine herniations occur as the brain extends under the falx in the supratentorial cerebrum. This may be the most common form of herniation although many authors in the past suggest transtentorial herniation is the most common. Perhaps this is due to the multitude of clinical symptomatology and urgency involved in transtentorial herniations. While subfalcine herniations often occur in conjunction with transtentorial herniation or in isolation. Presence however, does not necessarily lead to severe clinical symptomatology or alarm.
Subfalcine herniations can present clinically as headache.
Later on as the herniation progresses, contralateral leg weakness can occur. The imaging signs of subfalcine herniations include amputation of the ipsilateral anterior aspect to the frontal horn . This occurs as the mass effect truncates the anterior aspect of the frontal horn and widens the contralateral frontal horn. There is asymmetry at the anterior falx with a widened CSF space on the contralateral anterior falx . This image also demonstrates ipsilateral lateral ventricle compression with contralateral lateral ventricle and atria dilation.