Cerebellar mutism syndrome: current approaches to minimize risk for CMS

A Paravermal Trans-Cerebellar Approach to the Posterior Fossa Tumor Causes Hypertrophic Olivary Degeneration by Dentate Nucleus Injury

“…The majority of CMS patients was operated via a transvermian or telovelar approach (83.3%). Arguably, transvermian approaches and cranially extended telovelar approaches caused injury to the inferior vermis, a common cause for CMS [ 37 ]. Prior research has indicated that also injury to the DN as part of the cerebellar outflow pathway is a common cause of CMS, which might well explain CMS in the two patients with paravermal approach [ 17 ].…”

“…Noteworthily, in this study, midline operative approaches led to CMS in 12 out of 27 (44.4%) patients below the age of 18, indicating that vermal injury is a major factor in CMS pathology. The neurosurgical division from the Washington Children’s National Medical Center recently undertook a successful attempt to reduce the incidence of CMS by adopting practices to reducing intraoperative tissue trauma, including minimizing the degree of retraction utilized during the procedure and choosing telovelar approach over transvermian approach to obviate the need for vermial incision [ 37 ]. A 2019 international multicenter trial did not reveal surgical factors that predicted postoperative CMS, including surgical hydrocephalus treatment, prone position, ultrasonic aspirator or EVD use, telovelar approach and complete or near total resection [ 27 ].…”

“…Accordingly, sparing the inferior vermis may not suffice to prevent CMS and general intraoperative measures to prevent structural damage should be taken into consideration. In the literature, the reduction of thermal injury (by cavitronic ultrasonic aspirators) and minimization of mechanical injury (by surgical retraction) have been suggested to prevent cerebellar tissue injury [ 37 , 43 ]. Instead, application of slower progressing ‘vascular’ tissue-sparing, fissure dissecting approaches (e.g., telovelar or subtonsilar or supracerebellar) may be favorable [ 44 ].…”

“…The fact that the cerebello–thalamo–cortical (also termed dentato–thalamo–cortical) pathway involved in CMS development shares its proximal structures with the GMT (or DROP) responsible for HOD, a connection between the occurrences of the two entities is well conceivable and frequently discussed in the literature [ 10 , 35 ]. However, the risk reduction of operative injury to the efferent cerebellar pathways is undisputable paramount in the prevention of both, CMS and HOD [ 36 , 37 ]. Preventing such surgical injury in posterior fossa surgery is very complex due to the close proximity and exposure of cerebellar structures.…”

Endoscope-Assisted Neuroportal Transcerebellar Approach to the Fourth Ventricle: An Anatomical Study

“…4,7,[43][44][45] According to these observations, surgical dissection through the tonsillobiventral fissure according to the supratonsillar approach or splitting of the inferior vermis may result in DN and DRT tract injury, leading to postoperative neurological morbidities known as "posterior fossa syndrome." 5,[46][47][48][49][50][51][52][53] On the contrary, the DN is spared approaching the fourth ventricle through the cerebellomedullary fissure via the telovelar surgical path, as first described by Matsushima et al 54 The great advancements in endoscopic techniques have led to further less invasive approaches with limited transection of the brain parenchyma, which have minimized the risk of damages to these eloquent areas. [55][56][57][58][59][60] The main limitation of endoscopic techniques is represented by the restricted working channel, which does not allow the surgeon for bimanual manipulation, significantly reducing the surgical maneuverability.…”