Arachnoid Cysts: Entrapped Collections of Cerebrospinal Fluid Variably Communicating with the Subarachnoid Space

Abstract

Despite decades of investigation and discussion of the mechanisms involved in the pathophysiology of arachnoid cysts, fundamental issues concerning these entities remain poorly defined and controversial. Cine-mode magnetic resonance imaging (MRI) has shown two patterns of cerebrospinal fluid (CSF) flow within the cavity in patients harbouring arachnoid cysts. Some cysts present a harmonic flow with a patent flow entry zone. All these patients had intermittent, non-progressive and non-localizing symptoms requiring no surgery according to our criteria. The second pattern of CSF flow is more chaotic and is characterized by the presence of swirls throughout the entire cardiac cycle. This pattern is associated with a more disabling clinical picture. Some of these patients required surgical treatment. During surgery, an endoscope was used for inspection purposes revealing, above all, that arachnoid cysts always and variably communicate with the subarachnoid space. The CSF enters the cyst either through a patent flow entry zone or through minute perforations in areas more loosely packed of the arachnoid network that behave as a flexible mesh able to modify the area of flowing CSF. The slipstreams of CSF within arachnoid cysts may not be channelled properly leading to possible damage of the surrounding brain parenchyma.

Cisto aracnoide medular em um cão: relato de caso

“…Os casos descritos na literatura, em que os CAMs foram adquiridos após trauma, haviam feito mielografia antes de adquirir o cisto (Schmidt et al, 2007). Outra teoria levantada na medicina veterinária é que alguns pacientes adquirem o cisto congenitamente, porém apresentam sintomatologia associada a ele após contusão ou leve trauma (Galloway et al, 1999;Santamarta et al, 2001;Vernau et al, 2002). Esta teoria pode ter ocorrido na paciente deste relato, visto que apresentou crises de dor na coluna, sem diagnóstico da causa na época, anos antes da contusão.…”

“…Em humanos, acredita-se em casos congênitos, secundários a trauma, infecções, hemorragias na subaracnoide, punção da mielografia ou associados a outras lesões como disrrafismo espinhal (Nabors et al, 1988;Santamartaet al, 1995;Santamarta et al, 2001). Na veterinária, foram descritos casos congênitos (Rylander et al, 2002), após trauma, fratura (Skeen et al, 2003;Sugiyama e Simpson, 2009), cirurgias descompressivas do disco intervertebral (Rylander et al, 2002), e associadas ainda à espinha bífida (Jurina e Grevel, 2004), siringomielia (Galloway et al, 1999;Skeen et al, 2003), discoespondilite e espondilomielopatia cervical (Skeen et al, 2003).…”

“…Sugiyama e Simpson (2009) propuseram que há mais de um mecanismo para o desenvolvimento do cisto. Santamarta et al (1995) apresentaram a teoria da válvula unidirecional em cistos intracranianos em humanos, onde o tecido acometido gera entrada unidirecional de LCR com propulsão, e esta foi apoiada por Rylander et al(2002) na veterinária. Em outro estudo, foi demonstrado que há dois tipos de cistos em humanos: um tipo tem pulsação harmônica com a cardíaca, não causando sintomatologia clínica, enquanto o outro tipo tem uma forte turbulência do LCR produzindo sinais clínicos (Santamarta et al, 2001).…”

Comparative study on two surgical procedures for middle cranial fossa arachnoid cysts

“…It was reported that Cine-MRI as a new comer had identical effect as cisternography. We believe that Cine-MRI, as a new diagnostic means, with its more and more extensive application in clinical practice, will have great impact on the selection of surgical treatments in the future [9][10][11] . Our study indicated that epileptic seizure was also a common symptom of MCFAC.…”

Expanding cerebrospinal fluid cyst in the operative cavity: an unusual postoperative complication

“…This unusual postoperative complication has occasionally been described in the literature from different perspectives. [1][2][3] Case presentation Case 1. A 65-year-old man was admitted to our department following a generalised epileptic fit.…”