[Unexplained neurological dysfunction in the recovery room]. / Onverklaarde neurologische uitval in de uitslaapkamer.

BACKGROUND: Unexplained neurological dysfunction, which used to be known as conversion disorder, is rare following general anaesthesia. This phenomenon is difficult to identify in this situation because medically induced dysfunction (anaesthesia) turns into unexplained dysfunction. CASE DESCRIPTION: A 58-year-old man remained unresponsive to any stimuli for longer than expected following uncomplicated surgery under general anaesthesia, although his vital functions were normal. It was 2 hours after the operation before a slight eyelid response was shown. He then lay motionless in bed for several hours. Complete recovery of spontaneous movement and motor functions took 12 hours. No explanation was found. CONCLUSION: Unexplained neurological dysfunction can also occur following general anaesthesia. The diagnosis is made by neurological assessment. A wait-and-see approach is the management policy because the neurological dysfunction disappears spontaneously.

Clinical accuracy of the respiratory tumor tracking system of the cyberknife: assessment by analysis of log files.

PURPOSE: To quantify the clinical accuracy of the respiratory motion tracking system of the CyberKnife treatment device. METHODS AND MATERIALS: Data in log files of 44 lung cancer patients treated with tumor tracking were analyzed. Errors in the correlation model, which relates the internal target motion with the external breathing motion, were quantified. The correlation model error was compared with the geometric error obtained when no respiratory tracking was used. Errors in the prediction method were calculated by subtracting the predicted position from the actual measured position after 192.5 ms (the time lag to prediction in our current system). The prediction error was also measured for a time lag of 115 ms and a new prediction method. RESULTS: The mean correlation model errors were less than 0.3 mm. Standard deviations describing intrafraction variations around the whole-fraction mean error were 0.2 to 1.9 mm for cranio-caudal, 0.1 to 1.9 mm for left-right, and 0.2 to 2.5 mm for anterior-posterior directions. Without the use of respiratory tracking, these variations would have been 0.2 to 8.1 mm, 0.2 to 5.5 mm, and 0.2 to 4.4 mm. The overall mean prediction error was small (0.0 +/- 0.0 mm) for all directions. The intrafraction standard deviation ranged from 0.0 to 2.9 mm for a time delay of 192.5 ms but was halved by using the new prediction method. CONCLUSIONS: Analyses of the log files of real clinical cases have shown that the geometric error caused by respiratory motion is substantially reduced by the application of respiratory motion tracking.

Reducing monitor units for robotic radiosurgery by optimized use of multiple collimators.

Advances in image guidance and dose delivery techniques, and increased use of hypofractionation, have led to prolonged radiotherapy fraction duration. This is also the case with robotic radiosurgery, as extensive on-line image guidance procedures, many beams, and usually high fraction doses are used for tumor irradiation. At this institution, early stage non-small-cell lung cancer patients are treated with image guided tumor tracking for respiratory motion compensation. Approximately 130 circular beams and up to approximately 39 000 monitor units (MUs) are used for delivery of a total treatment dose of 60 Gy. The large number of MUs leads to long treatment times and the radiation leakage increases with the number of MUs. Generally, per patient, a single (small) cone is used. To substantially reduce the number of MUs, the authors have developed a new planning strategy for combined use of a small and a large cone. The large cone aims at dose delivery around the PTV center, while the small cone shapes the dose around the (irregular) PTV edges. The authors systematically investigated relationships between the number of MUs, the plan quality, the selected cone diameters, and the beam-direction setup. Plan quality was assessed with the conformity index, mean lung dose (MLD), V20 of the lungs, and by visual inspection. The reduction in MUs was determined by comparing two-cone plans with corresponding one-cone plans that yielded equal MLD, i.e., equal predicted lung toxicity. With the proposed two-cone approach, the required number of MUs reduced by on average 31% (range 4%-56%). The beam-on time per treatment fraction reduced by on average 8 min (range 1-15.2 min). All plans obeyed the clinically applied constraints and were considered clinically acceptable by an involved physician.

Endovascular coils as lung tumour markers in real-time tumour tracking stereotactic radiotherapy: preliminary results.

To evaluate the use of endovascular coils as markers for respiratory motion correction during high-dose stereotactic radiotherapy with the CyberKnife, an image-guided linear accelerator mounted on a robotic arm. Endovascular platinum embolisation coils were used to mark intrapulmonary lesions. The coils were placed in subsegmental pulmonary artery branches in close proximity to the target tumour. This procedure was attempted in 25 patients who were considered unsuitable candidates for standard transthoracic percutaneous insertion. Vascular coils (n = 87) were successfully inserted in 23 of 25 patients. Only minor complications were observed: haemoptysis during the procedure (one patient), development of pleural pain and fever on the day of procedure (one patient), and development of small infiltrative changes distal to the vascular coil (five patients). Fifty-seven coils (66% of total inserted number) could be used as tumour markers for delivery of biologically highly effective radiation doses with automated tracking during CyberKnife radiotherapy. Endovascular markers are safe and allow high-dose radiotherapy of lung tumours with CyberKnife, also in patients who are unsuitable candidates for standard transthoracic percutaneous marker insertion.

Analysis of the motion of oropharyngeal tumors and consequences in planning target volume determination.

PURPOSE: To determine adequate three-dimensional (3D) margins around the clinical target volume (CTV) of oropharyngeal cancers. METHODS AND MATERIALS: The CTV, bounded by implanted markers, was recorded under fluoroscopy in antero-posterior (AP) and lateral view. The peak-to-peak motion was measured in lateral, AP and cranio-caudal (CC) directions. RESULTS: During swallowing, the mean amplitude of motion measured was 9.4mm (0.9-18.5) and 4.1mm (0.6-11.4) in AP view in the CC and lateral direction, respectively; and 8.6mm (0.5-16.5) and 7.6mm (0.9-14.5) in lateral view in the CC and AP direction, respectively. In the non-swallowing period the motion was 1.5mm (0.3-3.2) and 1mm (0.4-3.6) in AP view in the CC and lateral direction, respectively; and 1.3mm (0.4-3.1) and 1.3mm (0.4-3.4) in lateral view in the CC and AP direction, respectively. This motion was believed to be due to breathing. CONCLUSION: If swallowing can be suppressed during CT acquisition, the contribution to the internal margin for this motion is negligible. Breathing related motion is also believed to be of limited clinical relevance in current practice. However, it might become of importance in future, with further reduction of margins.

Dysphagia disorders in patients with cancer of the oropharynx are significantly affected by the radiation therapy dose to the superior and middle constrictor muscle: a dose-effect relationship.

PURPOSE/OBJECTIVE: To assess the relationship between the radiation therapy (RT) dose received by the muscular components of the swallowing (sw) apparatus and - dysphagia related - quality of life (QoL) in oropharyngeal cancer. MATERIALS/METHODS: Between 2000 and 2005, 81 patients with SCC of the oropharynx were treated by 3DCRT or IMRT, with or without concomitant chemotherapy (CHT); 43 out of these 81 patients were boosted by brachytherapy (BT). Charts of 81 patients were reviewed with regard to late dysphagia complaints; 23% experienced severe dysphagia. Seventeen patients expired. Fifty-six out of 64 (88%) responded to quality of life (QoL) questionnaires; that is, the Performance Status Scales of List, EORTC H&N35, and the M.D. Anderson Dysphagia Inventory. The superior (scm), middle (mcm), and inferior constrictor muscle (icm), the cricopharyngeus muscle and the inlet of the esophagus, are considered of paramount importance for swallowing. The mean dose was calculated in the muscular structures. Univariate analysis and multivariate analysis were performed using the proportional odds model. RESULTS: Mean follow-up was 18 months (range 2-34) for IMRT, and 46 months for 3DCRT (range 2-72). At 3-years, a LRC of 84%, DFS of 78% and OS of 77% were observed. A significant correlation was observed between the mean dose in the scm and mcm, and severe dysphagia complaints (univariate analysis). A steep dose-effect relationship, with an increase of the probability of dysphagia of 19% with every additional 10 Gy, was established. In the multivariate analysis, BT (dose) was the only significant factor. CONCLUSION: A dose-effect relationship between dose and swallowing complaints was observed. One way to improve the QoL is to constrain the dose to be received by the swallowing muscles.