Long constructs in the thoracic and lumbar spine with a minimally invasive technique.

BACKGROUND: Literature about long implants used together with a minimally invasive spine surgery (MISS) technique is scarce. Our objective is to contribute our surgical experience in this field and to specifically focus on several technical details. PATIENTS AND METHODS: A digitally-dissected canal along the paravertebral muscles was created linking the stab wounds on each side in relation with the pedicles to be cannulated. Screws were inserted following the percutaneous technique. Long rods were modelled, threaded through the extender sleeves along the paravertebral canal and pushed into the screw heads with the reduction forceps. When fusion was needed, the facet complex was decorticated with a drill. To insert a cross-link, a canal between the 2 rods was digitally created and the spinous process was drilled. RESULTS: 8 patients underwent surgery (age range: 25-77 years). Indications were postosteomyelitis kyphosis in 3 patients, bone tumor in 3, and spine fracture in 2. No blood transfusions were necessary during or after surgery. A cross-link was inserted in 2 patients. Posterolateral bone fusion was attempted in 4, but radiologically identifiable in none. In one patient a cantilever manoeuvre was done to correct kyphosis. Mean duration of surgery was 4 h. There were no clinical complications related to the operation or the hardware (mean follow-up of 7.14 months, range: 1-15 months). CONCLUSION: The application of MISS techniques can be broadened to long spinal constructs to assess fractures, tumors or deformity, especially in elderly or debilitated patients. Nevertheless, posterolateral fusion is still a challenge through these limited exposures.

Design of an intracranial electrode for monitoring.

Direct recording of the electric brain activity gives more information than conventional electroencephalogram. Several authors have designed a variety of electrodes in order to solve the different problems of electrocorticography but in our opinion none of these fulfil the following features: easy implantation and extraction with minimal trauma; flexibility to allow placement over regions of the brain cortex that are difficult to access (interhemispheric fissure, medial aspect of the temporal lobe, frontobasal region, etc.), good quality recording. A multiple contact electrode which we think matches these features has been designed. Initially this electrode was tested in the postoperative monitoring of ten patients with supratentorial malignant tumours and in one case of intractable epilepsy. In two patients complications of treatment were detected, one had an epileptic seizure and the other had bleeding in the tumoural bed. In the first case a right temporal focus was delineated and posteriorly excised. Implantation of the electrode was always very simple, either from the craniotomy or from a burr hole, and its flexibility allowed us to place it over the regions above mentioned. Also the extraction was easy with a simple traction and without the need for a second intervention. In all cases the recording quality was excellent.