Dynamic telescopic craniotomy: a cadaveric study of a novel device and technique

OBJECT The authors assessed the feasibility of the dynamic decompressive craniotomy technique using a novel cranial fixation plate with a telescopic component. Following a craniotomy in human cadaver skulls, the telescopic plates were placed to cover the bur holes. The plates allow constrained outward movement of the bone flap upon an increase in intracranial pressure (ICP) and also prevent the bone flap from sinking once the ICP normalizes. The authors compared the extent of postcraniotomy ICP control after an abrupt increase in intracranial volume using the dynamic craniotomy technique versus the standard craniotomy or hinge craniotomy techniques. METHODS Fixation of the bone flap after craniotomy was performed in 5 cadaver skulls using 3 techniques: 1) dynamic telescopic craniotomy, 2) hinge craniotomy, and 3) standard craniotomy with fixed plates. The ability of each technique to allow for expansion during intracranial hypertension was evaluated by progressively increasing intracranial volume. Biomechanical evaluation of the telescopic plates with load-bearing tests was also undertaken. RESULTS Both the dynamic craniotomy and the hinge craniotomy techniques provided significant control of ICP during increases in intracranial volume as compared with the standard craniotomy technique. With the standard craniotomy, ICP increased from a mean of 11.4 to 100.1 mm Hg with the addition of 120 ml of intracranial volume. However, with the dynamic craniotomy, the addition of 120 ml of intracranial volume increased the ICP from a mean of 2.8 to 13.4 mm Hg, maintaining ICP within the normal range as compared with the standard craniotomy (p = 0.04). The dynamic craniotomy was also superior in controlling ICP as compared with the hinge craniotomy, providing expansion for an additional 40 ml of intracranial volume while maintaining ICP within a normal range (p = 0.008). Biomechanical load-bearing tests for the dynamic telescopic plates revealed rigid restriction of bone-flap sinking as compared with standard fixation plates and clamps. CONCLUSIONS The dynamic telescopic craniotomy technique with the novel cranial fixation plate provides superior control of ICP after an abrupt increase in intracranial volume as compared with the standard craniotomy and hinge craniotomy techniques.