Sylvian fissure arachnoid cysts: we do operate on them but should it be done?

Abstract

Very few nosographic entities of neurosurgical interest as Sylvian fissure arachnoid cysts arise doubt about their best management, especially when these lesions are incidentally discovered in asymptomatic subjects. Currently, the debate, as demonstrated by the papers published in this issue of Child’s Nervous System, seems to concern the most appropriate surgical technique and, more precisely, whether temporal arachnoid cysts should be approached endoscopically rather than by craniotomy and microsurgical manipulation. Apparently, both techniques assure similar rates of successes, failures, and complications. In my opinion, however, the discussion should address a more fundamental question that is whether the past experience has provided a sound demonstration that the surgical excision is necessary or, at least, advantageous in all the cases, including the asymptomatic ones. To be less controversial, I would at least discuss whether past failures in the management of these lesions have allowed to individuate reliable criteria to distinguish those subjects who may benefit of the surgical management from those who should be only observed. Sylvian fissure arachnoid cysts, commonly denominated temporal cysts, are characterized by some peculiar features which differentiate them from the analogous lesions developing in other intracranial or intraspinal locations. Besides to be often recognized in asymptomatic subjects, these cysts when associated to symptoms and signs have been reported in conjunction with a so large variety of clinical pictures that is logical to wonder whether the combination is really depending on a cause–effect relationship. Indeed, besides “traditional” clinical manifestations, namely headache, increased intracranial pressure, epilepsy, psychomotor retardation, and intracranial bleeding, considered to be the typical presentation of this type of malformation are attention deficit, hyperactivity, maniac depression, schizophrenia-like symptoms, paranoia, psychoses anosmia, Meniere’s disease, and hearing loss have been described in association with this malformation. From a survey published in this journal [1] aimed at analyzing the neurosurgeon’s attitude in case of symptomatic and asymptomatic temporal arachnoid cysts, it was apparent how the propension to operate increased when the symptoms and signs considered to be typical of these cysts were associated to the radiological image of a Galassi grade II temporal cyst (which was utilized to test the approach of several neurosurgeons from various international centers toward this type of lesion). However, when analyzed objectively on the grounds of the literature, the cause–effect relationship of these “classical” clinical manifestations of temporal arachnoid cysts appears to be quite questionable. Indeed, headache, which is reported in about 70% of symptomatic cases, is in most instances aspecific, chronic, unrelated to the cyst volume, or to the compression/distortion of the surrounding cerebrovascular structures. In most of the subjects who undergo intracranial pressure recording, these symptoms appear also unrelated to the intracystic pressure. Moreover, it is impossible to correlate postoperative brain re-expansion to the intracystic pressure. Concerning seizure disorder, the correlation with the presence of a Sylvian arachnoid cyst or the outcome following its surgical excision is uncertain. One fourth of This commentary refers to the article doi: 10.1007/s00381-009-0952-1.