A cranial fixation device comprising: a cap comprising: a central body having a mating connector with a threaded portion projecting from a distal end of the central body; a pair of wings extending radially out from the central body; and a first opening extending from a proximal end of the central body to the distal end of the central body and through the threaded portion of the mating connector, a base comprising: a threaded central opening corresponding to the threaded portion of the mating connector, the threaded central opening being positioned on a proximal end of the base; a distal threaded portion configured to engage with an opening in a skull; a pair of wings extending radially out from the threaded central opening; and a second opening extending through the threaded central opening and the distal threaded portion; and a compression grommet configured to be placed into the threaded central opening of the base, the compression grommet having a third opening extending from the proximal end to the distal end of the compression grommet, the first opening, the second opening and the third opening being aligned when the cap mates with the base and forms an instrument lumen configured to accept a portion of an instrument cable, the threaded portion of the cap being configured to mate with the threaded central opening of the base, and at least one wing of the pair of wings of the cap having a projection protruding in a direction towards the base, and the each wing of the pair of wings of the base having a seat, wherein, when the instrument cable extends through the instrument lumen, the projection from at least one wing of the pair of wings of the cap and at least one of the seats in the pair of wings of the base are configured to create a torque stop when a predetermined compression of the compression grommet is applied by tightening the cap on the base, and when the predetermined compression of the compression grommet is applied, the compression grommet compresses against the instrument cable fixing the instrument cable in place at a determined depth. a cap comprising: a central body having a mating connector with a threaded portion projecting from a distal end of the central body; a pair of wings extending radially out from the central body; and a first opening extending from a proximal end of the central body to the distal end of the central body and through the threaded portion of the mating connector, a central body having a mating connector with a threaded portion projecting from a distal end of the central body; a pair of wings extending radially out from the central body; and a first opening extending from a proximal end of the central body to the distal end of the central body and through the threaded portion of the mating connector, a base comprising: a threaded central opening corresponding to the threaded portion of the mating connector, the threaded central opening being positioned on a proximal end of the base; a distal threaded portion configured to engage with an opening in a skull; a pair of wings extending radially out from the threaded central opening; and a second opening extending through the threaded central opening and the distal threaded portion; and a compression grommet configured to be placed into the threaded central opening of the base, the compression grommet having a third opening extending from the proximal end to the distal end of the compression grommet, a threaded central opening corresponding to the threaded portion of the mating connector, the threaded central opening being positioned on a proximal end of the base; a distal threaded portion configured to engage with an opening in a skull; a pair of wings extending radially out from the threaded central opening; and a second opening extending through the threaded central opening and the distal threaded portion; and a compression grommet configured to be placed into the threaded central opening of the base, the compression grommet having a third opening extending from the proximal end to the distal end of the compression grommet, the first opening, the second opening and the third opening being aligned when the cap mates with the base and forms an instrument lumen configured to accept a portion of an instrument cable, the threaded portion of the cap being configured to mate with the threaded central opening of the base, and at least one wing of the pair of wings of the cap having a projection protruding in a direction towards the base, and the each wing of the pair of wings of the base having a seat, wherein, when the instrument cable extends through the instrument lumen, the projection from at least one wing of the pair of wings of the cap and at least one of the seats in the pair of wings of the base are configured to create a torque stop when a predetermined compression of the compression grommet is applied by tightening the cap on the base, and when the predetermined compression of the compression grommet is applied, the compression grommet compresses against the instrument cable fixing the instrument cable in place at a determined depth.