Arachnoid granulations of the middle cranial fossa

Abstract

We would like to applaud Chen et al. [2] on a superb study evaluating other locations of arachnoid granulations within the middle cranial fossa. These data help explain and further elucidate possible cerebrospinal Xuid absorption that occurs outside of the large arachnoid granulations found within the superior sagittal sinus and lacunae lateralis (Weed [4] Wrst described CSF reabsorption via the arachnoid granulations along the superior sagittal sinus in 1923). This is exempliWed in patients who have partial occlusion of the superior sagittal sinus but do not develop hydrocephalus. It is noteworthy that standard sources and textbooks usually do not mention such non-superior sagittal sinus/lateral lacunae locations. Other less known sites have been found along cranial nerves as they exit the cranium (e.g. jugular foramen), in the internal auditory meatus near the greater petrosal nerve’s emergence from the geniculate ganglion, and from the sheath of the trigeminal nerve as its parts traverse the cavernous sinus [1]. Additionally, these structures or at least arachnoid villi are identiWed along the spinal axis particularly at the nerve root sleeves [3]. We look forward to additional studies by these authors.