Early Bird or Night Owl: Insights into Dutch Students' Study Patterns using the Medical Faculty's E-learning Registrations.

Phenomenon: Educational activities for students are typically arranged without consideration of their preferences or peak performance hours. Students might prefer to study at different times based on their chronotype, aiming to optimize their performance. While face-to-face activities during the academic schedule do not offer flexibility and cannot reflect students' natural learning rhythm, asynchronous e-learning facilitates studying at one's preferred time. Given their ubiquitous accessibility, students can use e-learning resources according to their individual needs and preferences. E-learning usage data hence serves as a valuable proxy for certain study behaviors, presenting research opportunities to explore students' study patterns. This retrospective study aims to investigate when and for how long undergraduate students used medical e-learning modules. Approach: We performed a cross-sectional analysis of e-learning usage at one medical faculty in the Netherlands. We used data from 562 undergraduate multimedia e-learning modules for pre-clinical students, covering various medical topics over a span of two academic years (2018/19 and 2019/20). We employed educational data mining approaches to process the data and subsequently identified patterns in access times and durations. Findings: We obtained data from 70,805 e-learning sessions with 116,569 module visits and 1,495,342 page views. On average, students used e-learning for 16.8 min daily and stopped using a module after 10.2 min, but access patterns varied widely. E-learning was used seven days a week with an hourly access pattern during business hours on weekdays. Across all other times, there was a smooth increase or decrease in e-learning usage. During the week, more students started e-learning sessions in the morning (34.5% vs. 19.1%) while fewer students started in the afternoon (42.6% vs. 50.8%) and the evening (19.4% vs. 27.0%). We identified 'early bird' and 'night owl' user groups that show distinct study patterns. Insights: This retrospective educational data mining study reveals new insights into the study patterns of a complete student cohort during and outside lecture hours. These findings underline the value of 24/7 accessible study material. In addition, our findings may serve as a guide for researchers and educationalists seeking to develop more individualized educational programs.

[Advanced gastric cancer. Are there still indications for palliative surgical interventions?]. / Fortgeschrittenes Magenkarzinom. Gibt es noch Indikationen für Palliativeingriffe?

BACKGROUND AND METHODS: Based on data obtained in the prospective multicenter observational study on the surgical treatment of gastric cancer "East German Gastric Cancer Study 2002 (EGGCS)", the cohort of patients with gastric cancer who underwent palliative surgical interventions during the study period from 1(st) January to 31(st) December 2002 was investigated. RESULTS: Out of 1,139 documented patients with gastric cancer, 1,031 underwent a surgical intervention (operation rate 90.5%). In 70.4% (n=726) of the patients with surgical interventions, R0 resection status could be achieved whereas in 305 patients (29.6%), only a palliative (R1/2 resection status) result was possible using resection and non-resection procedures in 165 and 140 cases, respectively. The hospital mortality rate was 7.3% (n=53) in the group of curative R0 resection patients and was almost identical with 7.8% (n=13) in the group of R1/2 resection patients. The highest hospital mortality of 14.4% (n=20) was found in subjects who primarily underwent palliative surgical interventions (R2 resection or non-resection procedures). In the subgroup analysis the highest overall morbidity of 57.1% was found in the group of palliative (R2) resection patients. Curatively intended but palliatively operated patients (from the perspective of the final histopathological result) showed a significantly longer overall survival time (11 months) compared with patients who primarily underwent a surgical intervention with palliative intention (6.3 months). Even patients who underwent tumor resection with palliative intention were observed to have a longer survival time of 2.3 months (in total, 6.9 months) compared with patients with non-resection surgical intervention (4.6 months). In the group of R2 resection patients with a preoperatively detected pyloric stenosis/dysphagia, an increased overall morbidity (62.5% with stenosis versus 47.7% without stenosis) and an increased hospital mortality rate (25% versus 11.6%, respectively) were seen. This favors more interventional endoscopic procedures if possible considering the only marginal prolongation in survival time. In contrast, palliative resection in cases without stenosis is associated with an acceptable rate of postoperative complications (47.7%) and mortality (11.6%) resulting in the recommendation of a palliative resection under specific conditions considering the improved oncosurgical long-term outcome. CONCLUSION: Radical tumor resection with palliative intentions (if possible from a technical point of view) resulted in a prolongation of the median survival time of 3 months with an acceptable postoperative morbidity and mortality compared with non-resection procedures. According to the results of individual analysis of each tumor resection intervention, palliative gastrectomy showed a significant prolongation of survival time of 5 months compared with more limited subtotal resection (6 versus 11 months).

Microsurgical anatomy of the lateral approach to extraforaminal lumbar disc herniations.

OBJECTIVE: During the "lateral" approach to extraforaminal lumbar disc herniations, the surgeon may be confronted with considerable variations in anatomy, making this approach extremely difficult in some patients. An anatomic study, therefore, was undertaken to examine the bony boundaries of the operative target, the medial intertransverse space. METHODS: In 31 lumbar spine specimens taken from cadavers of people who had been between 30 and 93 years old at death, the relevant distances and proportions of the operative window were measured at the levels L1-L2 to L5-S1. RESULTS: Measurements revealed that the operative window in a systematic fashion becomes progressively smaller as the approach moves from L1-L2 toward L5-S1: 1) from L1 to L5, the medial boundary, the isthmus laminae, gradually extends farther laterally and eventually covers the waist of the respective vertebral body; 2) the lower boundary, the facet joint, gradually overlaps the disc space in an upward and lateral direction; 3) the upper boundary, the transverse process, gradually moves downward. Anatomic variations and abnormalities are found particularly often at the L5-S1 level. CONCLUSION: The anatomic findings led to important conclusions regarding the microsurgical approach to extraforaminal lumbar disc herniations; at levels L1-L2 to L3-L4, the midline approach with lateral retraction of the paraspinal muscles allows for efficient exposure of the lateral neural foramen and avoidance of trauma to the facet joint. Often at level L4-L5, and nearly always at level L5-S1, a tangential route through a paramedian transmuscular approach offers many advantages.

Seizure control following surgery in supratentorial cavernous malformations: a retrospective study in 77 patients.

Of 168 patients operated on consecutively for a supratentorial cavernous malformation, 77 had seizures as the initial symptom. The effectiveness of surgery in controlling seizures and the risk of surgery were evaluated by retrospective review of the patients' charts. The follow-up period was 1 to 9 years (mean 39 months) and the review period totalled 284 lesion-years. Only two patients showed postoperative deterioration in neurological status (morbidity risk: 2.6%), no patient died (mortality: 0%). Sixty-eight (88.3%) patients were seizure-free after operation and five (6.5%) showed a marked reduction in the frequency of their seizures. This corresponds to an overall positive effect of surgery of 94.8% of the patients. There was no substantial evidence that excision of the haemosiderin-stained tissue around the cavernoma along with the lesion itself provided better results than resection of only the cavernoma. Better results with regard to seizure control, however, were associated with shorter duration of symptoms before surgery.

Surgery of astrocytomas in the motor and premotor cortex under local anesthesia: report of 11 cases.

Under local anesthesia, gliomas of the premotor and primary motor cortex can be surgically removed with minimal morbidity. However, since these neoplasms exhibit an infiltrative growth pattern towards the pyramidal tract and are frequently not well delineated from functional motor cortex, the long-term outcome is unfavorable. In this series, 5 of 11 patients presented with a recurrent tumor within two years of operation. Two of these patients with recurrent tumors initially had a low grade glioma and three an anaplastic glioma. Due to the longer progression-free interval after surgery and the unpredictable course of patients with low grade gliomas, all efforts should be undertaken to achieve safe and radical resection with the use of intraoperative mapping and monitoring techniques as well as cryo-cut examinations at all tumor border zones to prove radicality. Since malignant tumors are known to recur in most instances, radical resection is justified only in functionally safe areas.

Stereotactic guided microsurgery of cerebral lesions.

A total of 33 patients presenting with various cerebral lesions were operated on with stereotactic guided craniotomy. In all cases the lesion could be totally removed and only one patient suffered from a recurrent metastasis. The survival time of patients with malignant brain tumors was in the range of the generally reported data. All the six patients with malignant gliomas developed a recurrence, four of them have since died. Three of the four patients with brain metastases died from systemic progression of their disease, and one patient died from a recurrence of a centrally located metastasis. A new neurological deficit occurred in only two patients. Despite the often deep or central localization of the lesions, major complications were rare. Stereotactic guidance and preoperative selection of the entry point allow a safer surgical procedure, a larger indication for open surgery in cases considered as not removable, and reduce surgical morbidity.

Circumscribed low grade astrocytomas in the dominant opercular and insular region: a pilot study.

Intraoperative mapping techniques allow a reliable identification or exclusion of eloquent brain areas and are well tolerated by the patients. In dominant opercular tumours radical surgery can only be achieved without lasting deficits with intraoperative histological examination of the resection line and mapping. If an early postoperative MRI shows residual opercular tumour in non-eloquent areas re-operation is recommended. In large dominant insular or opercular-insular tumours only biopsy is recommended, because only an incomplete removal can be accomplished, because the trial of radical removal carries a high risk of postoperative deficits due to possible vascular damage of the lenticulo-striate arteries or internal capsule. Because subtotal removal of low grade gliomas does not increase the progression free interval, we would not recommend surgery in these cases, as they carry a significant risk of a further deficit.

Space-occupying lesions of the sensori-motor region.

Successful surgery of the sensori-motor region requires precise pre- and intraoperative localization of the sensori-motor region and pyramidal tract. Important aids are the landmarks of cranio-cerebral topography, coronal suture and bregma and the sulcal anatomy of the sensori-motor region, which can be identified in CT or MR images. Due to considerable displacement and distortion of the anatomical structures, elicited by mass lesions, these aids often fail to render reliable support. In this situation, identification of the motor area can be achieved by electrical stimulation of the precentral gyrus in association with the recording of somatosensory evoked potentials of the pre- and postcentral gyrus. The localisation of the "motor mosaics" in relation to the lesion, enable determination of the direction of displacement of the motor strip and the fan of the pyramidal tract. Based on this information the most appropriate route of access to the lesion is selected, either transcortical or transsulcal. Lesion-specific operative techniques as well as location-specific approaches are discussed. With consequent application of these principles the risk of a new persistent motor deficit was as low as 4%. Thus, the indication for surgery in this area can now be set with greater confidence and far more generously than in the past.

Anatomy of the parietal lobe: mapping the individual pattern.

Using magnetic resonance imaging with planes of section tangential to the left or right perietal convexity, we studied the sulcus pattern of the parietal lobes in 50 healthy subjects. The postcentral sulcus and the intraparietal sulcus were easily identified. As a characteristic landmark, and corresponding to postmortem findings, both sulci joined in 77% of the 100 hemispheres. The presurgical recognition of individual parietal lobe anatomy may improve surgical planning, in particular with an intended persulcal approach.

[Stereotactically-guided microsurgery in cerebral processes]. / Stereotaktisch geleitete Mikrochirurgie zerebraler Prozesse.

Stereotaxy-guided microsurgery offers significant advantages in the treatment of deep-seated cerebral lesions, or in lesions that cannot reliably be localized because of their small size or lack of evident landmarks. We report our experience with 16 stereotaxy-guided microsurgical procedures performed with the Leksell or the Lerch stereotactic system. Small superficial lesions were operated on in 6 patients and deep-seated subcortical lesions in 10 patients. The lesion size ranged from 10 to 50 mm and the depth of the lesions varied between 5 and 65 mm. A trans-sulcus approach was chosen in patients with cavernomas and a transcortical or transtumoral one in patients presenting with cerebral tumors. In no patient was a new postoperative neurologic deficit found, i.e. 12 patients had neither a pre- nor a postoperative deficit. 2 patients (with central lesions) of 4 presenting with preoperative deficits showed an impressive recovery, while in the other 2 patients with lesions in the dominant temporal lobe the neurologic deficit remained unchanged. Stereotaxy-guided microsurgery allows safe resection of small or deep-seated cerebral lesions without postoperative morbidity in our series.

The subcranial approach for fronto-orbital and anteroposterior skull-base tumors.

We describe 78 patients with fronto-orbital and sphenoethmoidal tumors surgically treated with the subcranial approach. This approach was developed by us in 1978 primarily for the treatment of skull-base trauma and craniofacial anomalies. Since 1980, we have extended the indications to include tumor resections. This extended anterior exposure of the anterior fossa skull base, including the sphenoidal and clival planes, enables an en bloc tumor removal obviating the transfrontal approach or lateral rhinotomy. In contrast with the conventional transcranial approach, the anterior subcranial approach provides an extended exposure of these locations, avoiding frontal lobe retraction. Reduction of complications, such as recurrent cerebrospinal fluid leaks, postoperative brain edema, damage to cranial nerves, and infection plus decreased hospitalization, are the major advantages of this procedure.

CT-guided stereotactic aspiration and treatment of brain abscesses. An experience with 24 cases.

The present study reports our experience with stereotactic puncture, aspiration and drainage of brain abscesses in 24 patients from a series of 34 consecutive cases. In all patients an intracavitary catheter was left in place for external drainage and daily irrigation with antibiotics. The patients received pre- and postoperatively triple broad spectrum antibiotic treatment, associated with low dose steroids and anti-epileptic drugs. Follow-up CT scans showed immediate reduction of the abscess size and gradual diameter diminution of the enhancing ring structure until its disappearance. The clinical presentation, risk factors, aetiology, outcome, bacteriological and CT findings were analysed. Mortality in this series was 4%. The majority of patients (96%) had no or minimal disability according to the Glasgow Outcome Scale. Our results confirm the value of this treatment policy and suggest that the stereotactic technique is a simple and safe method with minimal mortality and morbidity in the treatment of the majority of chronic brain abscesses.

[Neurosurgical treatment of lumbar stenosis. A review of the literature]. / Neurochirurgische Behandlung der lumbalen Stenose. Eine Literaturübersicht.

Low back pain and claudicatio spinalis are typical for spinal stenosis. Neuroradiological diagnosis is best accomplished by a myelogram. The operative results in patients with a lumbar spinal canal stenosis are successful in 85.5%. Radicular pain responds better than lumbar pain. Severe complications such as new persistent neurological deficits are rare. If the operation is performed early the results are usually better than with delayed surgery. The decompression should be adapted to the type and extent of the stenosis. Additional removal of the disc as well as severe damage to the facet joints increases the risk of postoperative instability.

Subcortical topography and proportions of the pyramidal tract.

The pyramidal tract (PT) was dissected in 30 normal human hemispheres according to the method of Klingler. The various dimensions as well as the cerebral landmarks were studied. The pyramidal tract is built up like a fan in the white matter by a thin layer of fibers of 2.8-3.5 mm in thickness. The fibers converge toward the internal capsule to a solid fiber tract with a lateral and apdiameter of 7.8 +/- 1.6 mm and 17.5 +/- 2.1 mm, respectively. This configuration of the PT presents different possibilities of damage during surgery. The evaluation of the three-dimensional course of the PT is possible by using three cerebral landmarks, the precentral gyrus, the entrance into the internal capsule and the posterior limb of the internal capsule. Their topography is described. Additionally the pyramidal tract can be defined medially by the sulcus cinguli and the roof of the lateral ventricle and laterally by the superior sulcus circularis Insulae. The possible displacement of the PT by space occupying lesions and the intra-operative orientation is discussed.

Are there typical localisations of lumbar disc herniations? A prospective study.

A prospective intra-operative analysis of the location of lumbar disc herniation was performed in 131 patients with verified 54% contained (incomplete) and 46% non-contained (complete) lumbar disc herniations. Bulging discs or protrusions are not included in this study. Complete disc herniations occurred more frequently in the upper lumbar spine. The localization of the lumbar disc herniations within its segment showed no correlation to the affected level. 64% of the disc herniations were located medio-laterally, 20% laterally, 12% within or lateral of the intervertebral compartment and 5% in the midline. Nearly one third of all herniations were found at the level of the disc space. Medio-lateral disc herniations were displaced more often in a caudal direction, lateral herniations were found displaced upwards and downwards with similar frequency while extraforminal herniations migrated significantly more often in a cranial direction. The pathomechanism and anatomical pathways of disc fragment migration are discussed on the basis of a new concept of the anterior extradural space.

Localization of central lesions by correlation of CT findings and neurological deficits.

In a prospective study involving 100 patients with lesions in the precentral gyrus or pyramidal tract we sought to correlate clinical findings and the results of an axial computed tomography (CT) to localize the lesion. In 85% of patients the size and location of the lesion visible on CT correlated well with the type and severity of the neurological symptoms and signs. However, in the remaining 15% of patients the CT findings did not correlate well with the patient's neurological deficit, showing that in these patients the anatomy of the central area was variable or distorted by the space-occupying lesion. We suggest that in such patients neurophysiological techniques be used intra-operatively for reliable localization of the motor strip.

Safe surgery of lesions near the motor cortex using intra-operative mapping techniques: a report on 50 patients.

In 50 patients lesions located in or adjacent to the motor strip were microsurgically removed with the help of intra-operative electrophysiological mapping of the sensorimotor cortex. Mapping consisted of cortical stimulation and/or recording of somatosensory evoked potentials. Depending on the patient's pre-operative neurological status, surprisingly good results could be achieved: The surgery resulted in increased permanent sensorimotor deficit in only 4% of cases and in improved neurological status in 30% of cases. It is concluded that surgical removal of centrally located lesions using a microsurgical technique and intra-operative mapping of the motor cortex is safe and permits extensive or radical resection of lesions, even those in the motor cortex itself.