The impact of the reference imaging modality, registration method and intraoperative flat-panel computed tomography on the accuracy of the ROSA® stereotactic robot.

OBJECTIVE: To establish the impact of the imaging modality, registration method and use of intraoperative computed tomography (CT) scan on the accuracy of the ROSA® stereotactic robot. METHODS: Using a dedicated phantom device, we measured the accuracy of the stereotactic robot for 20 targets as a function of the registration method (frameless, FL, or frame-based, FB) and the reference imaging modality (3T magnetic resonance imaging, MRI, CT scanner or flat-panel CT, fpCT). We performed a retrospective study of the accuracy of the first 26 FB and 31 FL robotized stereotactic surgeries performed in our department. RESULTS: In a phantom study, the mean target accuracy was 1.59 mm for 3T MRI-guided FL surgery, 0.3 mm for fpCT-guided FL surgery and 0.3 mm for CT-guided FB surgery. In our retrospective series, the mean accuracy was 0.81 mm for FB stereotactic surgery, 1.22 mm for our 24 stereotactic surgery procedures with FL (surface recognition) registration and 0.7 mm for our 7 stereotactic surgery procedures with FL fiducial marker registration. Intraoperative fpCT fully corrected all the registration errors. CONCLUSIONS: The ROSA stereotactic robot is highly accurate. Robotized FB stereotactic surgery is more accurate than robotized FL stereotactic surgery.

High-resolution 3-dimensional T2*-weighted angiography (HR 3-D SWAN): an optimized 3-T magnetic resonance imaging sequence for targeting the subthalamic nucleus.

BACKGROUND: Subthalamic nucleus deep brain stimulation (STN-DBS) is an established treatment for Parkinson's disease. OBJECTIVE: To characterize an optimized magnetic resonance imaging (MRI) sequence (high-resolution 3-dimensional T2*-weighted angiography [HR 3-D SWAN]) for direct STN targeting. METHODS: Sequence distortions were measured using the Leksell stereotactic phantom. Eight consecutive candidates for STN-DBS underwent HR 3-D SWAN MRI for direct identification of the 16 STN. Two senior neurosurgeons independently determined the boundaries of STN on a semiquantitative scale (ranging from 1 [identification very easy] to 4 [identification very difficult]) and the anatomic target within the nucleus. The anatomic data were compared with electrophysiological recordings (48 microrecordings). We examined the anatomic location of the active contacts on MRI. RESULTS: The mean distortion error over the phantom was 0.16 mm. For the 16 STNs, identification of the upper, internal, anterior, and external edges was considered to be easy (scores of 1 or 2). The distinction between the substantia nigra and the STN was rated 1 or 2 for all but 6 nuclei. In the mediolateral axis, electrophysiological recordings covered perfectly anatomic data. In the craniocaudal axis, the mean differences between the electrophysiological data and the anatomic data were 0.8 mm and 0.19 mm for the "entry" and "exit" of the STN, respectively. All active contacts were located within the STN on MRI. CONCLUSION: HR 3-D SWAN allows easy visualization of the STN. Adapted to stereotactic requirement, the sequence simplifies direct targeting in STN-DBS surgery.

Cognitive impairment and dementia after intracerebral hemorrhage: a cross-sectional study of a hospital-based series.

BACKGROUND: Frequencies of cognitive impairment and dementia have not been assessed in spontaneous intracerebral hemorrhage (ICH). The objective of this study was to determine the frequencies and patterns of cognitive impairment and dementia in a cross-sectional study of consecutive patients hospitalized in a single university medical center. METHODS: Of 183 consecutive patients hospitalized between 2002 and 2006, 80 survivors were contacted and 78 were included (mean time since stroke 40 months). Thirty patients were scored with the Informant Questionnaire on Cognitive Decline in the Elderly and Instrumental Activities of Daily Living in a telephone interview, and 48 underwent a comprehensive clinical and neuropsychological assessment. RESULTS: Dementia was observed in 18 of 78 patients (23%; 95% confidence interval [CI] 13-32%) and cognitive impairment without dementia was seen in 37 of 48 patients (77%; 95% CI 65-89%). The cognitive disorders mainly concerned episodic memory (52%), psychomotor speed (44%), and executive function (37%), followed by language and visuoconstructive abilities. In a logistic regression analysis, Rankin score >1 at discharge and hemorrhage volume were the initial factors to be selected as a predictor of long-term dementia. CONCLUSIONS: This single-center, cross-sectional study revealed that the prevalence of dementia and cognitive impairment without dementia after ICH are high and are similar to those observed in cerebral infarct. Further longitudinal, prospective studies are required to assess accurately the prevalence, mechanisms and predictors of post-ICH dementia.

The article critique as a problem-based teaching method for medical students early in their training: a French example using anatomy.

In France, "article critique" became a particular teaching method in the second part of the medical curriculum. It approaches a reading exercise of scientific medical papers similar to that of journal club. It could be compared to reviewing a paper as performed by reviewers of a scientific journal. We studied the relevancy of that teaching method for the youngest medical students. Our questions were about the understanding and the analyzing ability of a scientific paper while students have just learned basic medical sciences as anatomy. We have included 54 "article critique" written by voluntary students in second and third years of medical cursus. All of the IMRaD structure items (introduction, materials and methods, results and discussion) were analyzed using a qualitative scale for understanding as for analyzing ability. For understanding, 89-96% was good or fair and for the analyzing ability, 93-100% was good or fair. The anatomical papers were better understood than therapeutic or paraclinical studies, but without statistical difference, except for the introduction chapter. Results for analyzing ability were various according to the subject of the papers. This teaching method could be compared to a self-learning method, but also to a problem-based learning method. For the youngest students, the lack of medical knowledge aroused the curiosity. Their enthusiasm to learn new medical subjects remained full. The authors would insist on the requirement of rigorous lessons about evidence-based medicine and IMRaD structure and on a necessary companionship of the students by the teachers.

Anatomic study of the superficial peroneal nerve using sonography.

OBJECTIVE: The purpose of our study was to show that sonography allows precise assessment of the location and course of the superficial peroneal nerve and of its relationship with other structures. MATERIALS AND METHODS: This study, initially undertaken in cadavers, was followed by sonographic studies of 30 healthy adult volunteers (60 legs) by two radiologists in consensus. The location and course of the superficial peroneal nerve and its relationship with the adjacent anatomic structures were analyzed. RESULTS: The entire course of the superficial peroneal nerve could be identified using sonography. The level at which the superficial peroneal nerve emerges between the peroneus longus and extensor digitorum longus muscles and the level at which it pierces the crural fascia and becomes subcutaneous were found to be highly variable. The superficial peroneal nerve was found to be located in the anterior compartment in 26.7% of the legs and to divide before piercing the crural fascia in 6.7% of the legs. CONCLUSION: The superficial peroneal nerve can be clearly depicted by sonography. Knowledge of the nerve's precise location, which may show individual variations, may have useful clinical applications.