Brain manipulation/retraction is an essential step to access deep lesions in the brain parenchyma or the base of the skull. Throughout the development of neurosurgery, retraction was developed from simple handheld to self-retaining retractors for the sake of freeing the surgeons’ hands, minimizing fatigue and tremors, especially with the introduction of micro-neurosurgery [1, 2].
Those benefits are not without hazards, as there are possible risks of tissue injury associated with prolonged retraction, especially at the tip of the retractor. Retraction injuries occur secondary to direct mechanical trauma or from vascular compromise in the form of edema and ischemia. It is difficult to assess or expect the amount of injury, but the damages range from mild transient edema to chronic cortical changes, massive edema, and even mortality. It has been estimated that brain retraction injury occurs in approximately 10% of major cranial base tumor procedures or 5% of intracranial aneurysm surgeries [3, 4, 7,8,9,10].
This has led to the appearance of techniques to predict or to minimize that risk. Preoperative imaging for detection of susceptible parts of the cortex and planning the position of retractors were studied. Intraoperative methods to detect cerebral damage like monitoring of local cerebral blood flow, intracranial pressure, and cerebral metabolism using microdialysis, also were discussed. Other methods are the technical modifications of the retractors to lessen the pressure from metallic retractors, like sponge or balloon-based retractors, or the use of Fogarty catheters filled with air. None of the previous methods had gained popularity. The other option is the intermittent release of the retractor every 5 min, and the use of multiple retractors instead of one to avoid localizing the pressure on a small area of the brain [1, 10,11,12,13,14,15].
In concordance with several authors, we focused in this study on the success of avoiding the use of fixed retraction, but dynamic retraction using the surgical instruments in the surgeon hands. This could be achieved by relying on basic surgical steps that are amenable when applied properly, and in the absence of sophisticated intraoperative equipment. The main steps are proper patient positioning to benefit from the gravity, design of the craniotomy, choice of natural corridors to avoid brain transgression, proper arachnoid dissection, and CSF aspiration [1, 6, 16,17,18,19,20,21,22].
Patient positioning and craniotomy design are two simple and effective steps to avoid fixed retraction, although not specific for. Their proper application benefits from the gravity to pull on the brain, avoid unnecessary retraction, and use the dual folds to retain parts of the brain instead of retracting them. We used cotton rolls as soft retraction in a number of cases where the approach is between the falx or the tent from one side and the brain from the other side. This is similar to the idea of Spena et al. who used Fogarty catheter filled with air as soft retractors [16].
The craniotomy flap design is important too, adding few millimeters in the skull base, or to cross the dural sinuses in interhemispheric approaches avoids undue retraction [1, 6].
Microscopic magnification to open subarachnoid spaces, address the brain tumor interface and later tumor debulking to decrease the intracranial pressure is a must. Extensive arachnoid dissection unlocks the brain lobes, allows CSF aspiration thus minimizes the ICP and limits the need for retraction. We begin to open arachnoid cisterns before handling the tumor in all cases except in approaches not related to cisterns with large subarachnoid spaces, like interhemispheric approach, where we had to do ventricular tapping. Some authors reported the used of arachnoid retraction to avoid fixed retraction using sutures or clips applied to the arachnoid temporarily during surgery [1, 5, 16, 17, 23].
The use of special surgical tools can help the surgeon to apply dynamic retraction more easily. Examples are the use of microscope with mouth piece, lighting instruments, and single shaft tools [1, 5, 7]. Their use unblocks the field, free the operator hands, and limit repeated change of the microspore angle [1, 6]. In our study, we used the navigation in some cases as it was not always available, but otherwise we relied on basic microsurgical tools and the above-mentioned methods.
Other measures to reduce intracranial pressure were applied infrequently in our patients, like lumbar drainage and ventricular tapping. Preplanned lumbar drain, although advised by some authors, was used in 2 cases (1.6%) only as it is not preferred by the authors, while intraoperative ventricular tapping was done in 4 cases (3.2%) where no access to basal cisterns to aspirate CSF [16, 19].
We had to use fixed retractors transiently in 7 cases (5.7%) due to persistent high intracranial pressure or large masses where the surgeon needs to use both hands in the field unhindered by retracting the brain. This agrees also with similar studies that dynamic retraction was not always possible, and the authors were obliged to use fixed retraction in some cases, although we did not have matching intraoperative facilities [1, 5, 6, 21, 22].
