Introduction: Hemorrhagic cavernous malformations involving the lateral pontine region require complex surgical considerations in order to maximize complete resection of the cavernoma and associated hemorrhage while minimizing morbidity. We describe our experience through the middle fossa rhomboid approach in eight children with cavernomas involving the pons, with lateralized hemorrhages extending through the pontine parenchyma.
Methods: Eight children underwent this approach over a 10 year period at Rady Children’s Hospital of San Diego. There were 5 females and 3 males with a mean age of 13.2 years (±4.6 years). Six lesions were lateralized to the left and two to the right. An extended rhomboid approach was utilized in all patients. Landmarks were based upon the Fukushima dual fan model, which delineates this region by (1) the junction of the GSPN and V3; (2) the lateral edge of the porous trigeminus; (3) the intersection of the petrous ridge and arcuate eminence, and (4) the intersection of the GSPN, geniculate ganglion, and AE.
Maximal bone removal was extended inferiorly beyond the inferior petrosal sinus to the clivus; posteriorly for unroofing the IAC; laterally for skeletonizing the geniculate ganglion, GSPN, and ICA; and anteriorly under the Gasserian ganglion. In all cases the lesions were approached posteromedially to the basilar artery at the junction of CNVI, superior to AICA, and lateral to the trigeminal origin. Retraction of V3 allowed for our ability to avoid the region involving CNIV and the SCA.
Results: Seven cavernomas were completely resected, while a second peripheral lesion was not resected with the primary lesion in one patient. One patient had a transient CNVI palsy and two had transient trigeminal hypaesthesia/dysaesthesia. One CSF leak require oversewing of the wound.
Conclusions: The middle fossa approach should be taken into consideration when an approach requiring minimal morbidity is needed to confront these complex lesions.
Patient Care: To illustrate a safe and effective approach to dealing with a complex lesion in a challenging area of the brain in children.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) understand the indication for the middle fossa approach in children with pontine cavernomas, 2) understand the salient anatomy involved with the middle fossa approach, 3) understand the techniques used to maximize the exposure of the middle fossa approach, and 4) understand the potential complications with the middle fossa approach.