chapter  11
18 Pages

Stereotactic Image-Guided Surgery

Interest in the development of stereotactic surgery in humans had been documented in the literature as early as the nineteenth century.1-4 The idea is to accurately localise anatomical structure within the human body. It was recognised that this can be achieved by recreating a 3D construct using three planes designated X (horizontal), Y (coronal), and Z (sagittal).2 A coordinate can then be used to localise structures with precious positioning. However, a rigid xation is needed, as slight movement could result in displacement of coordination. A rigid frame was then developed which is xed to a known external landmark to create stability which provided the most accurate positioning. This novel technique is termed stereotaxy or stereotactic guidance. These terms are derived from the Greek words stereos meaning three dimension and taxis meaning orderly arrangement.2,5 The word tactic originated from a Latin word meaning to touch.5,6 Several prototypes of stereotactic frames have been developed around the world, but their benet remained within the neurosurgery and head/neck surgery community. The modern era of stereotactic technology was marked by the development of radio-imaging technology such as computer technology (CT) and magnetic resonance imaging (MRI), computer software, and digital signalling. These technologies have allowed stereotactic techniques to become frameless. This was able to allow the instrument to be used anywhere on the human body without the need to xate patients into a rigid frame. The ability to see ne soft tissue anatomical detail with the use of CT and MRI coupled with navigation tools

11.1 Overview ............................................................................................................................... 141 11.2 History of Stereotactic Image-Guided Navigation ............................................................... 142

11.2.1 Early Stereotaxy Development ................................................................................. 142 11.2.2 Modern Stereotactic and Its Expansion in Medicine................................................ 143

11.3 Stereotactic Imaging Navigation in Preoperative Flap Reconstruction ............................... 144 11.3.1 Fiducial Marking Technique ..................................................................................... 144 11.3.2 Surface Landmark: soft-touch Registration and Z-touch Surface-Matching

Registration ............................................................................................................... 145 11.4 Clinical Use in Preoperative Flap Reconstruction Imaging ................................................. 146

11.4.1 Use of Stereotactic Image-Guided Preoperative Imaging for DIEP Flaps............... 146 11.4.2 Procedure .................................................................................................................. 149 11.4.3 Use of Stereotactic Image-Guided Preoperative Imaging for ALT Flaps ................ 150 11.4.4 Procedure .................................................................................................................. 150

11.5 Summary .............................................................................................................................. 154 References ...................................................................................................................................... 156

allow localisation and detail descriptions of vessel perforators. Rozen et al. have taken the idea and expanded the potential use of stereotactic image guidance in preoperative ap reconstruction planning. CT-guided stereotaxy has improved the accuracy and provided real-time navigation systems for reconstructive surgeons in performing ap reconstructions.7-9

The use of navigation techniques to accurately map anatomical structures has been pioneered since the late 1800s. It is heavily utilised in the eld of neurosurgery. It began with Dittmar who in 1873 used a guiding device in mice to create bulbar vasomotor centres in rats.1 In 1889, Zernove, a Russian anatomist, developed an encephalometer that allows mapping of surface topography for the localisation of the cranial sutures and cerebral sulci.3 The advancement in stereotaxy arrived in 1908, by Sir Victor Horsley, a British neurophysiologist and neurosurgeon, and his associate Robert Clarke, a mathematician.2 Their work was originally to answer the question whether or not the cerebellar cortex is directly connected to the peduncles and spinal cord. In order to identify the pathway of connection, they needed to cause a destruction of the cerebellar nuclei. If the pathway existed, then the nerve bre of the peduncles and spinal cord should not undergo degenerative changes. One major obstacle remained: How can a discrete and accurate destruction be made to the cerebellar nuclei without damaging the surrounding structure? The answer is through a navigation instrument. Horsley and Clarke developed the Horsley-Clarke frame, which allowed an accurate placement of an insulated needle which delivered electrode electrocoagulation into the nuclei resulting in cerebral tissue necrosis.4 The device utilises three planes: a line connecting the lower margin of the orbit and the external auditory meatus is the horizontal reference, the frontal (coronal) line passes through the two auditory canals, and the sagittal line bisects the head between these two planes. The frame is screwed onto the skull with the orientation along the horizontal plane. The frontal and sagittal planes can be created by adjusting the perpendicular and bisecting lines, respectively. Their experiments on the animal heads allowed an extraordinary precious mapping of the relationship between the intra-cranial and extra-cranial structures in a 3D form.2,4

Despite the success of their work and patency by Clarke, the development of a human model stereotactic apparatus had never been constructed. It was not until 1918 when Aubrey Mussen, a Canadian neuroanatomist and neurophysiologist, modied the original Horsley-Clarke apparatus to be useable in humans.4,10-12 He designed a rectangular brass frame attached to the patient’s head by ear bars, which were able to be inserted into the external auditory canals, and a clamp xed to the infraorbital ridge. Mussen also developed the rst human stereotactic atlas based on cranial landmarks that was similar to Clarke’s animal stereotactic atlas. However, Mussen’s stereotactic instrument was used only in laboratory experiment and never used in the clinical setting.4,6 His work remained unnoticed for many years and had not been mentioned in the scientic community at the time. The work was not resurrected until 30 years later, in 1947 with Spiegel, an American neurologist who began developing his own stereotactic device for humans in the clinical setting. The device was much similar to that of Horsley and Clarke apparatus which xed onto the patient’s skull. However, an intraoperative radiography was incorporated into the procedure to help in localising intra-cranial structures.4 In 1952, Spiegel and Wycic developed the rst stereotactic atlas of the human brain which allowed them to perform a targeting localisation with précised sectioning of the brain, a procedure which they termed stereoencephalotomy.1,4 The procedure avoids the need for an open neurosurgical operation which carried a high mortality rate due to it precise identication of affected lesion which prevents unnecessary destruction of the cerebral tissue. Since then, several designs of stereotactic frames have been developed in various international centres. These innovations have paved the way for a modern era of stereotactic technology.