Case Studies

Case 1

A twenty five year old man presented with a subarachnoid haemorrhage. An admission CT scan revealed a cerebellar arterio-venous malformation (AVM). Subsequent angiography revealed a complex AVM with multiple flow related aneurysms on its feeding arteries. Given the patient's young age and the history of haemorrhage, it was decided that surgical excision of the AVM was the safest option. To assist surgical planning, navigation and patient consent for surgery, a biomodel was requested. A helical CT angiogram was performed and the data were prepared using Anatomics™ BioBuild™ software. Stereocol resin was used to allow selective colouration of the vascular structures. The biomodel accurately replicated the AVM (Figure 3.3). Initially the biomodel was used to obtain informed consent from the patient and

Figure 3.3 Case 1: (a) biomodel of a mid-line cerebellar AVM; (b) sterilized biomodel being used intraoperatively

Figure 3.3 Case 1: (a) biomodel of a mid-line cerebellar AVM; (b) sterilized biomodel being used intraoperatively his family. The complexity of the abnormality could easily be appreciated. The risks of the surgery and location of the surgical exposure were also easily explained to the patient and his family. The biomodel was used in conjunction with the preoperative angiogram to plan the surgical approach and the selective obliteration of the feeding vessels to the AVM. The surgeon consulted with an interventional radiologist carefully to select vessels that would be difficult to obliterate surgically. The biomodel was helpful as a communication and planning aid. The surgeon was able to evaluate the access to the AVM and plan the sequence of the surgery. During the operation, the biomodel was invaluable in assisting with surgical navigation and in verifying the location of various vessels supplying the AVM. The biomodel was also used to demonstrate the abnormality to nursing and junior medical staff. Post-operatively the patient made a full recovery and was cured of the AVM.

Case 2

A fifty three year old man presented with seizures caused by a known recurrent parafalcine meningioma. Surgery had been performed on three separate occasions but unfortunately the tumour had recurred. A large part of the skull had been resected and tumour was invading the edges of the cranial deficit as well as the soft tissues and brain. A contrast CT scan was performed. Using AnatomicsTM BioBuildTM software, the surgeon marked on the CT scan the limit of tumour invasion with a line. A biomodel was manufactured from StereoCol resin with the line represented by red colouration. The surgeon then used standard equipment to plan and simulate the skull resection on the biomodel. The 'resected' biomodel was then returned to AnatomicsTM. A custom acrylic implant was then manufactured to reconstruct the defect (Figure 3.4). A custom resection template was also manufactured to allow the surgeon to mark the resection line on the patient's skull. The biomodel, implant and resection template were used to demonstrate the surgical plan to the patient and obtain informed consent. At surgery the patient's scalp was carefully dissected from the tumour and the skull. The resection template was then contour matched to the skull and the resection margin marked. The tumour mass was then resected from the skull and carefully dissected from the brain. The skull was then reconstructed using the custom implant. The patient made a satisfactory recovery, had an excellent cosmetic result and has been tumour free and seizure free since the surgery.

Case 3

A thirty two year old man presented with a focal epileptic seizure. A CT scan revealed an abnormality in his brain suspicious of a tumour. A biopsy was requested. The patient had three non-invasive fiducial markers placed and a contrast CT scan was performed. The data were transferred to an AnatomicsTM BioBuildTM workstation and a biomodel was manufactured of the skull, fiducial markers and the tumour with associated blood vessels. The biomodel was used to gain informed consent from the patient. The patient was taken to the operating theatre. The D'Urso stereotactic frame was placed on the biomodel and the trajectory was set and locked into the frame. The biopsy depth was also determined. The frame was then attached to the three fiducial markers and an entry point was marked on the skin. A small linear incision was made and a burrhole was performed. The frame was again verified and then the biomodel was attached to the patient fiducials. The biopsy needle was then gently inserted to the target and biopsies were taken (Figure 3.5). The procedure took 20 min to perform. The biopsy was positive for tumour. The patient made an uneventful post-operative recovery.

Rapid Prototyping Implants

Figure 3.4 Case 2: (a) biomodel with tumour invading skull. Resection margin marked; (b) biomodel with simulated tumour resection; (c) biomodel with resection template; (d) biomodel with custom cranioplastic implant; (e) resection template fitted to patient intraoperatively

Figure 3.4 Case 2: (a) biomodel with tumour invading skull. Resection margin marked; (b) biomodel with simulated tumour resection; (c) biomodel with resection template; (d) biomodel with custom cranioplastic implant; (e) resection template fitted to patient intraoperatively

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