The retrosigmoid trans-middle cerebellar peduncle approach for pontine cavernous malformations: multicenter...

Intrinsic pontine cavernous malformations represent one of the most challenging entities in neurosurgery because of their deep location and close proximity to critical brainstem nuclei and long tracts. Traditional surgical approaches are associated with considerable morbidity due to transgression of eloquent neural tissue. The identification of the trans-middle cerebellar peduncle (trans-MCP) approach, has enabled safer access to selected pontine lesions. However, apart from publications of the center where the trans-MCP approach was introduced (Phoenix), little is known about its use and surgical outcome.

Patients with symptomatic intrinsic pontine cavernous malformations were treated via a retrosigmoid trans-MCP approach at three academic neurosurgical centers. Data were obtained from institutional databases and included clinical presentation, imaging characteristics, surgical details, and follow-up outcomes.

Five patients (3 men, 2 women; mean age 44.8 years) were included. All lesions were intrinsically located within the pons without pial or ependymal surface presentation and demonstrated typical hemorrhage MRI characteristics with mass effect on adjacent structures. The median preoperative mRS was 4 (range 1-4), and recurrent hemorrhage before surgery occurred in 3/5 patients. The retrosigmoid trans-MCP approach was performed with neurophysiological monitoring. Gross total resection was achieved in all instances. Postoperative neurological morbidity occurred in all five patients but was predominantly transient. At follow-up (range 4-14 months), no residual or recurrent cavernous malformations were detected on MRI. Neurological status had improved in all cases. Residual symptoms were minor and included mild ataxia, facial hypesthesia, dysarthria, or vertigo. Functional outcomes were favorable, with a median follow-up mRS of 1 (range 1-2).

The retrosigmoid trans-MCP approach represents a relatively safe, effective, and reproducible surgical strategy for selected pontine cavernous malformations. When performed by experienced surgeons, this approach can be successfully implemented across specialized centers.