Nachshon Knoller

Application of transcranial doppler ultrasonography for the diagnosis of brain death.

Objective: To determine the clinical validity of transcranial Doppler ultrasonographic (TCD) signs of total cerebral circulatory arrest for confirmation of brain death and to define the test protocol. Design: Study of a diagnostic test. Setting: General and neurosurgery intensive care units. Patients: 137 patients in a coma (Glasgow Coma Score 3–5), caused by various pathological conditions, observed from January 1992 to July 1998. 84 patients met the clinical criteria of brain death; 43 patients out of 137 received sedative drug therapy and 31 of these developed brain death. Results: Total cerebral circulatory arrest was demonstrated by TCD in 81 patients. All of them proved to be brain dead according to subsequent clinical examination In 29 of 31 patients who had received sedative drug therapy TCD examination showed total cerebral circulatory arrest 12–48 h before the formal confirmation of the diagnosis. In 1 out of 84 clinically brain dead patients a false negative result was obtained. In 2 of 84 cases, no clear signals from intracranial vessels were obtainable. Fifty-three patients who did not meet the clinical criteria for brain death showed no TCD signs of total cerebral circulatory arrest. The specificity of the TCD test for confirmation of brain death was 100 % and the sensitivity 96.5 %. Conclusions: In agreement with previously published data, we conclude that TCD ultrasonography is a highly specific and sensitive confirmatory test and should be included as an additional test in the protocol for the assessment of brain death.

Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: Part I--Technical development and a test case result.

OBJECTIVE:To introduce a new miniature robot (SpineAssist; MAZOR Surgical Technologies, Caesarea, Israel) that has been developed and tested as a surgical assistant for accurate percutaneous placement of pedicle screws and translaminar facet screws. METHODS:Virtual projections in three planes—axial, lateral, and anteroposterior—are reconstructed for each vertebra from a preoperative computed tomographic (CT) scan. On a specially designed graphic user interface with proprietary software, the surgeon plans the trajectory of the screws. Intraoperative fluoroscopic x-rays with targeting devices are then matched with the CT-based virtual images, as well as the surgeons plan. A clamp is attached to the spinous process or a minimally invasive frame (Hover-T frame; MAZOR Surgical Technologies) is mounted to the iliac crest and one spinous process. The miniature robot is then attached to the clamp and/or frame. On the basis of combined CT scan and fluoroscopic data, the robot aligns itself to the desired entry point and trajectory, as dictated by the surgeons preoperative plan. RESULTS:A test case in a cadaver lumbar spine was performed in which four screws and two rods were inserted, using a minimally invasive technique, combining the SpineAssist system and Hover-T frame in conjunction with the PathFinder system (Spinal Concept Inc., Austin, TX). The discrepancy between the planned and actual screw trajectories was measured by means of postprocedural CT scan. Overall, the four screws were implanted with an average deviation of 1.02 ± 0.56 mm (range, 0–1.5 mm) from the surgeons plan. CONCLUSION:These preliminary results confirm the systems accuracy and support its use in minimally invasive spine surgery applications.

Substance abuse, traumatic brain injury and neuropsychological outcome

The neuropsychological performance of 119 patients with severe closed traumatic brain injury (TBI) who had received toxicology screens at the time of trauma centre admission was examined. Three groups were created: normal screen, positive alcohol screen, or positive abused drugs screen (with or without the presence of alcohol). The admitting Glasgow Coma Scale (GCS) score was significantly lower in the positive alcohol screen group than the normal screen group, while the three groups did not differ in length of post-traumatic amnesia (PTA) or years of education. Neuropsychological assessment was conducted during inpatient rehabilitation, following resolution of PTA. Normal screen patients obtained significantly better scores than the abused-drugs patients on the Full Scale IQ (FIQ) and Verbal IQ (VIQ) indices of the Wechsler Adult Intelligence Scale-Revised and the Verbal Memory, General Memory, Attention-Concentration, and Delayed Recall indices of the Wechsler Memory Scale-Revised. Normal screen patients also scored significantly higher than positive alcohol screen patients on FIQ and VIQ indices and all five indices from the Wechsler Memory Scale-Revised. These data suggest the existence of an additive effect of substance abuse on neuropsychological outcome in TBI. Findings have potential implications for both acute management and rehabilitation of TBI.

Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: part 2--Evaluation of system accuracy.

OBJECTIVE To evaluate the accuracy of a novel bone-mounted miniature robotic system for percutaneous placement of pedicle and translaminar facet screws. METHODS Thirty-five spinal levels in 10 cadavers were instrumented. Each cadavers entire torso was scanned before the procedure. Surgeons planned optimal entry points and trajectories for screws on reconstructed three-dimensional virtual x-rays of each vertebra. Either a clamp or a minimally invasive external frame was attached to the bony anatomy. Anteroposterior and lateral fluoroscopic images using targeting devices were obtained and automatically registered with the virtual x-rays of each vertebra generated from the computed tomographic scan obtained before the procedure. A miniature robot was mounted onto the clamp and external frame and the system controlled the robots motions to align the cannulated drill guide along the planned trajectory. A drill bit was introduced through the cannulated guide and a hole was drilled through the cortex. Then, K-wires were introduced and advanced through the same cannulated guide and left inside the cadaver. The cadavers were scanned with computed tomography after the procedure and the systems accuracy was evaluated in three planes, comparing K-wire positions with the preoperative plan. A total of fifty-five procedures were evaluated. RESULTS Twenty-nine of 32 K-wires and all four screws were placed with less than 1.5 mm of deviation; average deviation was 0.87 ± 0.63 mm (range, 0–1.7 mm) from the preoperative plan in this group. Sixteen of 19 K-wires were placed with less than 1.5 mm of deviation. There was one broken and one bent K-wire. Another K-wire was misplaced because of collision with the previously placed wire on the contralateral side of the same vertebra because of a mistake in planning, resulting in a 6.5-mm deviation. When this case was excluded, average deviation was 0.82 ± 0.65 mm (range, 0–1.5 mm). CONCLUSION These results verify the systems accuracy and support its use for minimally invasive spine surgery in selected patients.

Robotic assisted spinal surgery - from concept to clinical practice

After several years of product development, animal trials and human cadaver testing, the SpineAssist®–a miniature bone-mounted robotic system–has recently entered clinical use. To the best of the authors’ knowledge, this is the only available image-based mechanical guidance system that enables pedicle screw insertion with an overall accuracy in the range of 1 mm in both open and minimally invasive procedures. In this paper, we describe the development and clinical trial process that has brought the SpineAssist to its current state, with an emphasis on the various difficulties encountered along the way and the corresponding solutions. All aspects of product development are discussed, including mechanical design, CT-to-fluoroscopy image registration, and surgical techniques. Finally, we describe a series of preclinical trials with human cadavers, as well as clinical use, which verify the systems accuracy and efficacy.

Spontaneous spinal epidural hematoma: The importance of preoperative neurological status and rapid intervention

We describe the presentation, management, and outcome of spontaneous spinal epidural hematoma (SSEH) in two tertiary academic centers. We retrospectively reviewed clinical and imaging files in patients diagnosed with SSEH from 2002-2011. Neurologic status was assessed using the American Spinal Injury Association (ASIA) Impairment Scale (AIS). A total of 17 patients (10 females; mean age 54 years, range 10-89) were included. Among patients presenting with AIS A, 5/8 showed no improvement and 3/8 reached AIS C. Among those presenting with AIS C, 5/6 reached AIS E and 1/6 reached AIS D. Of those presenting with AIS D, 3/3 reached AIS E. Mean time-to-surgery (TTS) was 28 hours (range 3-96). TTS surgery in two patients remaining at AIS A was ⩽ 12 hours; in 4/8 patients recovering to AIS E it was > 12 hours, including three patients operated on after > 24 hours. In patients remaining at AIS A, a mean of 4.4 levels were treated compared with means of 3.7 and 3.5 in those with AIS C and E, respectively, at late follow-up. In this series, preoperative neurological status had greater impact on late outcome than time from symptom onset to surgery in patients with SSEH.

Ventriculoperitoneal shunt malfunction due to migration of the abdominal catheter into the scrotum

A case is reported in which the peritoneal portion of a ventriculoperitoneal shunt migrated into the scrotum via an indirect inguinal hernia and caused cerebrospinal fluid hydrocele with shunt malfunction.

Delayed intraventricular tension pneumocephalus complicating posterior fossa surgery for cerebellar medulloblastoma

A child is described in whom intraventricular tension pneumocephalus developed 10 days after removal of a cerebellar medulloblastoma and 1 day after suture removal. The tension pneumocephalus was associated with hydrocephalus and CSF leakage from the suture line. The symptoms of the pneumocephalus were rapidly progressing loss of consciousness and hemiplegia which were promptly reversed upon aspiration of the intracranial air. A large amount of intraventricular air present in the immediate postoperative period was, however, clinically silent. The characteristics of this unusual presentation, its relation to asymptomatic pneumocephalus. hydrocephalus and the preventive and therapeutic measures required to deal with such conditions are discussed.

In vivo multiparametric monitoring of brain functions under intracranial hypertension following mannitol administration

Abstract Objective: Over the last 20 years, mannitol has replaced other osmotic diuretics. Its beneficial effects on intracranial pressure (ICP), cerebral perfusion pressure (CPP), cerebral blood flow (CBF) and brain metabolism are widely accepted. In the present study, we tested the effect of mannitol injection on brain hemodynamic, metabolic, ionic and electrical state in rats exposed to intracranial hypertension. Methods: The parameters monitored simultaneously included ICP, CBF using the laser Doppler flowmetry, mitochondrial NADH redox state by the fluorometric technique, extracellular K+ and H+ levels, DC potential, ECoG, blood pressure and calculated CPP. ICP was elevated to 30 mmHg for 30 minutes and mannitol was injected 15 minutes post-ICP elevation. Results: Our results showed that mannitol decreased ICP, and improved the levels of MAP, CPP and CBF. Moreover, mannitol completely prevented mortality following intracranial hypertension in rats. Conclusion: It seems that the multiparametric monitoring approach, used in intracranial hypertension models, is an important tool for brain functional state evaluation.

Incidence and injury characteristics of traumatic brain injury: Comparison between children, adults and seniors in Israel

Abstract Aim: To assess the incidence and injury characteristics of hospitalized trauma patients diagnosed with TBI. Methods: A retrospective study of all injured hospitalized patients recorded in the National Trauma Registry at 19 trauma centres in Israel between 2002–2011. Incidence and injury characteristics were examined among children, adults and seniors. Results: The annual incidence rate of hospitalized TBI for the Israeli population in 2011 was 31.8/100 000. Age-specific incidence was highest among seniors with a dramatic decrease in TBI-related mortality rate among them. Adults, in comparison to children and seniors, had higher rates of severe TBI, severe and critical injuries, more admission to the intensive care unit, underwent surgery, were hospitalization for more than 2 weeks and were discharged to rehabilitation. After adjusting for age, gender, ethnicity, mechanism of injury and injury severity score, TBI-related in-hospital mortality was higher among seniors and adults compared to children. Conclusion: Seniors are at high risk for TBI-related in-hospital mortality, although adults had more severe and critical injuries and utilized more hospital resources. However, seniors showed the most significant reduction in mortality rate during the study period. Appropriate intervention programmes should be designed and implemented, targeted to reduce TBI among high risk groups.