Single-center long-term results of vagus nerve stimulation for pediatric epilepsy: a 10-17-year follow-up study.

PURPOSE: A retrospective study, based on a prospectively built database, presents the results of long-term follow-up care of pediatric vagus nerve stimulation (VNS) patients in terms of seizure outcome, surgical aspects, the potential impact of maturation, and medication changes. METHODS: From a prospectively built database, 16 VNS patients (median age 12.0 years, range 6.0 to 16.0 years; median seizure duration 6.5 years, range 2.0 to 15.5 years) followed for at least 10 years were graded as non-responder - NR (seizure frequency reduction < 50%), responder - R (reduction ≥ 50% and < 80%), and 80% responder - 80R (reduction ≥ 80%). Data about surgical aspects (battery replacement, system complications), seizure dynamics, and medication changes were taken from the database. RESULTS: The early percentages of good results (80R + R) were 43.8% (year 1), 50.0% (year 2), and 43.8% (year 3). These percentages remained stable between years 10 and 12 (50% year 10; 46.7% year 11; 50% year 12) and increased in years 16 (60%) and 17 (75%). Depleted batteries were replaced in ten patients, six of whom were either R or 80R. In the four NR, the indication for replacement was improved quality of life. Three patients had VNS explanted or switched off-one had repeated asystolia and two were NR. The effect of hormonal changes in menarche on seizure was not proven. During the study, antiseizure medication was changed in all patients. CONCLUSIONS: The study proved the efficacy and safety of VNS in pediatric patients over an exceptionally long follow-up period. The demand for battery replacements indicates a positive treatment effect.

Factors responsible for early postoperative mental alterations after bilateral implantation of subthalamic electrodes.

INTRODUCTION: Early postoperative mental changes are the most frequent problem after bilateral subthalamic electrode implantation. The study aims to find an association between them and factors related to patient, disease and surgery, including the size of the third ventricle as brain atrophy marker. MATERIAL AND METHODS: The study included 80 patients with bilateral subthalamic electrodes implanted for motor complications of Parkinson's disease (PD). Patients' age, disease and motor complications duration, medication, neuropsychological tests, surgical reports, third ventricle length (intercommissural distance) and width (intermammillary distance) were analysed. RESULTS: Early mental alterations requiring treatment were observed in 25.0% of patients with higher age being significant predictor. The duration of PD motor complications, L DOPA equivalent dose, DSR Mattis, third ventricle length and width were not statistically significant predictors. The incidence of postoperative mental alteration with intermammillary distance > 8 mm was 60%. The percentage of left sided electrodes implanted in anterior trajectory is significantly higher in patients with early mental changes. CONCLUSIONS: Higher age is a risk factor for early postoperative mental changes, but not disease, late motor complications duration and parameters describing third ventricular size except the excessive intermammillary distance. Left sided electrode implanted in anterior position is a risk factor.

[The Impact of Corticotherapy on the Diagnostic Yield of Stereotactic Biopsy in Patients with Brain Lymphoma]. / Vliv kortikoterapie na diagnostickou výteznost stereotaktické biopsie u nemocných s lymfomem mozku.

Backround: Because of the dismal prognosis of untreated brain lymphoma early histological verification using stereobiopsy is decisive for patient with this disease. The study analysed the diagnostic yield of stereobiopsy in brain lymphoma patients with respect to prebiopsy corticosteroid administration. PATIENTS AND METHODS: Patients with brain lymphomas were identified in a group of 162 stereotactic biopsies (108 frame-based and 54 frameless) of patients harboring suspected brain tumor. Non conclusive biopsies were reevaluated to exclude the possibility of missed lymphoma. RESULTS: Total 9 patients (8.3%) and 4 patients (7.4%) had lymphomas in the frame-based and frameless stereobiopsy groups, resp. In 10 patients, corticosteroid treatment of perifocal brain oedema was conducted continually up until biopsy (including one patient with corticotherapy for pulmonary disease). Lesion regression was observed in 6 of these patients. Transient lesion remission was observed during corticotherapy in one patient with lesion recurrence after steroid discontinuation. In 2 patients, corticosteroids were not administered before biopsy. The results of stereobiopsy were inconclusive in 8 patients (4.9%). Before biopsy, the possibility of brain lymphoma was considered in 3 patients, but the final diagnoses were autoimmune vasculitis, histological changes after embolic events from the thrombosed pulmonary veins in pulmonary malformation and local inflammation. CONCLUSION: Although the extent of brain lymphoma decreased after corticosteroid administration, corticotherapy does not exclude valid diagnostic biopsy.Key words: brain lymphoma - stereotaxic techniques - frameless stereotaxy - stereotactic biopsy - corticosreroids Part of the message was presented on XLI. Brno Oncological Days within the Glio Meeting and published in the form of a short abstract. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 27. 5. 2017Accepted: 2. 7. 2017.

Is hydrocephalus after spinal cord injury really caused by the injured spinal cord? Two case reports and a literature review.

UNLABELLED: Posttraumatic hydrocephalus caused by cerebrospinal fluid circulation disturbances frequently complicates the clinical course and treatment after craniocerebral injury. Hydrocephalus complicating spinal cord injury is only exceptionally reported. The paper presents two cases of complete cervical spinal cord injury with subsequent development of hydrocephalus. The analysis of both cases and literature data confirmed the dominant role of non-spinal factors in the development of hydrocephalus after spinal cord injury. Despite the exceptional occurrence of hydrocephalus after spinal cord injury, this diagnosis should be considered in cases of delayed deterioration of a patient with cervical spinal cord injury, particularly if cerebrospinal fluid space abnormalities and posttraumatic subarachnoid haemorrhage are present. KEY WORDS: spinal cord injury hydrocephalus subarachnoid hemorrhage Blakes pouch cyst neuroendoscopy.

[The effect of anticoagulation and anti-aggregation treatment on the extent, development and prognosis of acute craniocerebral injury]. / Vliv antikoagulacní a antiagregacní terapie na rozsah, vývoj a prognózu akutního kraniocerebrálního poranení

PURPOSE OF THE STUDY: A retrospective analysis of the effect of anticoagulation and anti-aggregation treatments on the post-injury clinical status, frequency of necessary surgical interventions including re-operations, course of intracranial haemorrhage dynamics and treatment outcome in patients with acute traumatic intracranial haematoma. MATERIAL AND METHODS: The group consisted of 328 patients with acute post-traumatic intracranial haemorrhage treated at the author's institution from 2008 to 2012. Fifteen patients with anticoagulation therapy (warfarin; 8 females, 7 males; median age, 72.0 years) and 46 patients with anti-aggregation treatment (21 females, 25 males; median age, 75.5 years ; 37 with acetylsalicylic acid, 5 with thienopyridines, 2 with new antithrombotics and 2 taking dual anti-aggregation therapy), all older than 55 years, were included in statistical analysis. The post-injury clinical condition (Glasgow Coma Scale), incidence of haemorrhagic contusions, intracranial haematoma progression, particularly when surgery was indicated, incidence of re-operations and treatment outcome (Glasgow Outcome Scale - GOS) were the study parameters. The control group included 77 patients with post-traumatic intracranial haematoma with normal coagulation who were older than 55 years (27 females, 50 males; median age, 67 years). Patients younger than 55 years and those with normal coagulation were not included in the statistical analysis. The treatment of all patients with anti-aggregation or anticoagulation therapy was consulted with the haematology specialist. RESULTS: The median age and initial status evaluated by the Glasgow Coma Scale were similar in the groups of anti-aggregated and anticoagulated patients and the control group. The number of good treatment outcomes, as evaluated by the GOS, was significantly higher in the anti-aggregated patients than in those on warfarin. A comparison of anti-aggregated, anticoagulated and normal coagulation patients did not show any statistically significant differences in the incidence of patients operated on, in the incidence of haemorrhagic contusions requiring surgery as a marker of the severity of brain parenchyma injury, intracranial haemorrhage progression with time, particularly when requiring surgery, and the rate of re-operations. However, when comparing the group of anti-aggregated patients with the control group, the higher incidence of haemorrhagic contusions and the lower number of patients requiring surgery were found to be close to the level of statistical significance. DISCUSSION: The positive effect of anti-aggregation and anticoagulation treatment on the morbidity and mortality from cardiovascular diseases should be regarded in relation to a higher risk of haemorrhagic complications. If a bleeding complication occurs, the possibility of neutralising this treatment should be considered, but this is particularly difficult in new agents. The relationship between anti-aggregation or anticoagulation treatment and the treatment results in the patients with head injury is particularly important from the neurosurgical point of view, because the relevant literature data are ambiguous. CONCLUSIONS: The results did not confirm any statistically significant adverse effects of anticoagulation or anti-aggregation treatment on the severity of post-injury status and risk of intracranial bleeding progression. The incidence of poor outcomes is higher in anticoagulated patients than in anti-aggregated patients. Although not reaching the level of statistical significance, the results also indicate higher risk of significant haemorrhagic brain contusions in anti-aggregated patients.

Long-term vagus nerve stimulation in children with focal epilepsy.

OBJECTIVES: The aim of the study was to evaluate the long-term efficacy and hospitalization rates in children with refractory focal epilepsy treated by vagus nerve stimulation. MATERIALS AND METHODS: We retrospectively analyzed 15 children with intractable focal epilepsy treated by vagus nerve stimulation (mean age of 14.6 ± 2.5 years at the time of implantation). We analyzed the treatment effectiveness at 1, 2, and 5 year follow-up visits. We counted the average number of urgent hospitalizations and number of days of urgent hospitalization per year for each patient before and after the VNS implantation. RESULTS: The mean seizure reduction was 42.5% at 1 year, 54.9% at 2 years, and 58.3% at 5 years. The number of responders was 7 (46.7%) at 1 year and 9 (60%) at both 2 and 5 years. The mean number of urgent hospitalizations per patient was 1.0 ± 0.6 per year preoperatively and 0.3 ± 0.5 per year post-operatively (P < 0.0001). The mean number of days of urgent hospitalization per patient was 9.3 ± 6.1 per year preoperatively and 1.3 ± 1.8 per year post-operatively ( < 0.0001). CONCLUSIONS: Vagus nerve stimulation is an effective method of treating children with refractory focal epilepsy. It leads to a substantial decrease in the number and duration of urgent hospitalizations.

Subthalamic electrode implantation using the MicroDrive system and the importance of microrecording data.

OBJECTIVE: The aim of the paper was to describe the relationship of the anatomical and electrophysiological target for the subthalamic electrode implantation in Parkinson's disease patients defined as the best electrophysiological recordings from multiple paralel electrodes tracts with a target discrepancy explanation. BACKGROUND: Although microrecording is the standard in subthalamic stimulation, microelectrode monitoring prolongs surgical time and may increase the risk of haemorrhagic complications. The main purpose for the electrophysiological mapping is to overcome the discrepancy between the anatomical and electrophysiological targets. METHODS: Subthalamic electrodes were stereotactically implanted in 58 patients using microrecording by means of parallel electrodes at defined distances. The relationship of the final electrode to the anatomical trajectory, the subthalamic nucleus electrical activity length, and the relationship of right and left electrodes were analysed. RESULTS: The final electrode placement matched the anatomical trajectory in 53.4 % of patients on the right side, and 43.1 % of patients on the left side. The electrode position was symmetrical in 38.3 % of patients. The analysis of left and right electrode positions did not prove brain shift as the sole factor responsible for anatomy-functional discrepancy. Further, neither age, Parkinson's disease duration, or L-DOPA adverse effects were confirmed as responsible factors. CONCLUSIONS: The difference between the anatomical trajectory and the final electrode placement underlined the need for functional microelectrode monitoring. Brain shift is not the only causative factor for the difference (Tab. 7, Ref. 27).

[The effect of age, alcohol intoxication and type of brain injury on the prognosis of patients operated on for craniocerebral trauma]. / Vliv veku, alkoholové intoxikace a charakteru poranení mozku na prognózu operovaných zranených s kraniocerebrálním poranením.

INTRODUCTION: Advanced age is reported to be an important negative prognostic factor for the final functional outcome in patients after craniocerebral injury. Worse prognosis can also be expected in the presence of significant brain contusion, requiring surgical treatment because of expansive behaviour. Definite adverse influence of alcohol intoxication at the time of injury has not been proven by current literature data. The aim of the study is to analyse the importance of the above mentioned factors for the treatment outcome in patients operated on for craniocerebral injury. MATERIAL AND METHODS: In the group of 246 patients with craniocerebral injury operated on between 2007 and 2011, the authors focused on the influence of age (145 patients < 60 years, 101 patients > 60 years), alcohol intoxication at the moment of injury (blood alcohol level over 0.1% based mainly on serum osmolarity plus clinical signs of alcohol intoxication) and the presence of brain contusion requiring surgical decompression on the final clinical outcome (using the Glasgow Outcome Scale). RESULTS: 54.1% of patients under 60 years of age were alcohol-intoxicated at the moment of injury. The incidence of alcohol intoxication in patients older than 60 years was 35.7%. The incidence of expansive brain contusions requiring surgical decompression was higher in patients older than 60 years and patients with alcohol intoxication. Statistical analysis of prognosis as related to age has shown significantly worse prognosis in patients older than 60 years. The difference was also significant in the subgroup of non-intoxicated patients. Statistical analysis did not show worse prognosis in alcohol-intoxicated patients. The presence of significant contusions influenced the injury prognosis only in patients younger than 60 years. CONCLUSION: The impact of age on the final treatment outcome in patients with craniocerebral injury was proven. The study did not show significant deleterious effect of alcohol intoxication at the time of injury on the final outcome.

Entropy in scalp EEG can be used as a preimplantation marker for VNS efficacy.

Vagus nerve stimulation (VNS) is a therapeutic option in drug-resistant epilepsy. VNS leads to ≥ 50% seizure reduction in 50 to 60% of patients, termed "responders". The remaining 40 to 50% of patients, "non-responders", exhibit seizure reduction < 50%. Our work aims to differentiate between these two patient groups in preimplantation EEG analysis by employing several Entropy methods. We identified 59 drug-resistant epilepsy patients treated with VNS. We established their response to VNS in terms of responders and non-responders. A preimplantation EEG with eyes open/closed, photic stimulation, and hyperventilation was found for each patient. The EEG was segmented into eight time intervals within four standard frequency bands. In all, 32 EEG segments were obtained. Seven Entropy methods were calculated for all segments. Subsequently, VNS responders and non-responders were compared using individual Entropy methods. VNS responders and non-responders differed significantly in all Entropy methods except Approximate Entropy. Spectral Entropy revealed the highest number of EEG segments differentiating between responders and non-responders. The most useful frequency band distinguishing responders and non-responders was the alpha frequency, and the most helpful time interval was hyperventilation and rest 4 (the end of EEG recording).

[Pharmacoresistant epilepsy after craniocerebral injury]. / Farmakorezistentní epilepsie po kraniocerebrálním poranení.

INTRODUCTION: Posttraumatic epilepsy is one of the possible serious consequencies of both closed and open head injury with clinical manifestation months or years after surgery. In pharmacoresistant patients, surgical therapy should be considered. MATERIAL AND METHODS: The study summarises the results of surgical treatment of pharmacoresistant posttraumatic epilepsy in a group of 13 patients (11 males and 2 females). Average age at the time of injury was 9.6 years in males and 8.8 years in females. The average number of seizures was 10.7-17 seizures/month preoperatively. Invasive EEG monitoring was required in 5 patients in whom non invasive or semiinvasive investigations failed to localize the epileptogenic zone adequately. Temporal lobe resections were performed in 4 patients, 4 patients underwent extratemporal resections and vagus nerve stimulation system was implanted in 5 patients. RESULTS: Three patients (75%) after temporal resections became seizure free (Engel I) and in the remaining patient significant reduction of seizures was achieved (Engel III). There were 2 seizure free patients after extratemporal resections (50%) and significant reduction of seizure rates was achieved (Engel III) in the remaining two. One patient after vagus nerve stimulation met the criteria for > 90% response and there was a 50-90% seizure rate reduction in the remaining 4 patients (vagus nerve stimulation responder). CONCLUSIONS: Although in limited group of patients the study confirms good results of surgical treatment of selected posttraumatic epilepsy patients--mainly temporal epilepsy patients and patients after vagus nerve stimulation. Meticulous presurgical evaluation including invasive encephalography in indicated patients is a precondition for surgical success.

Transduction profiles in minipig following MRI guided delivery of AAV-5 into thalamic and corona radiata areas.

BACKGROUND: As a step towards clinical use of AAV-mediated gene therapy, brains of large animals are used to settle delivery parameters as most brain connections, and relative sizes in large animals and primates, are reasonably common. Prior to application in the clinic, approaches that have shown to be successful in rodent models are tested in larger animal species, such as dogs, non-human primates, and in this case, minipigs. NEW METHOD: We evaluated alternate delivery routes to target the basal ganglia by injections into the more superficial corona radiata, and, deeper into the brain, the thalamus. Anatomically known connections can be used to predict the expression of the transgene following infusion of AAV5. For optimal control over delivery of the vector with regards to anatomical location in the brain and spread in the tissue, we have used magnetic resonance image-guided convection-enhanced diffusion delivery. RESULTS: While the transduction of the cortex was observed, only partial transduction of the basal ganglia was achieved via the corona radiata. Thalamic administration, on the other hand, resulted in widespread transduction from the midbrain to the frontal cortex COMPARISON WITH EXISTING METHODS: Compared to other methods, such as delivery directly to the striatum, thalamic injection may provide an alternative when for instance, injection into the basal ganglia directly is not feasible. CONCLUSIONS: The study results suggest that thalamic administration of AAV5 has significant potential for indications where the transduction of specific areas of the brain is required.

[Neuroendoscopic biopsy of a brain tumor]. / Neuroendoskopická biopsie tumoru mozku.

BACKGROUNDS: Neuroendoscopic biopsy is one of the techniques that can be used for histological verification of a suspected brain tumor. The use of neuroendoscopy is particularly useful for cystic tumors and para- and intraventricular brain tumors that are risky for stereotactic biopsy. The technique of navigated neuroendoscopy enables biopsy sampling under visual control, haemostasis of biopsy site and treatment of cerebrospinal fluid pathways obstruction. PATIENTS AND METHODS: Neuroendoscopic technique was used for biopsy in one patient with a solid brain tumor. 23 patients (12 males, mean age 49.7 years, range 21-75 years and 11 females, mean age 59.1 years, range 22-76 years) with a suspected cystic brain tumor underwent neuroendoscopic biopsy. Suspected intra- or paraventricular brain tumor presented indication for neuroendoscopic biopsy in 36 patients (20 males, mean age 43.9 years, range 6-80 years and 16 females, mean age 46.2 years, range 11-78 years). RESULTS: High grade glioma was most frequently diagnosed in patients with cystic brain tumors, followed by low grade gliomas and metastatic tumors. Diagnostic sample was obtained from all patients. Tumor resection was performed in 7 patients with a cystic tumor after neuroendoscopic biopsy and histological findings were identical in 70.1% of them. Similarly, high grade glioma was most frequently diagnosed in patients with intra or paraventricular tumors, followed by tumors originating from pineal region tissues. Diagnostic sample was obtained from 94.3% of patients. Tumor resection was performed in 5 patients after neuroendoscopic biopsy and histological findings of the resected tissue was identical with neuroendoscopic biopsy in 4 of them (80%). CONCLUSIONS: Neuroendoscopy is a safe biopsy technique for a subset of patients who are high risk for the use of stereotactic biopsy, with comparable results. Neuroendoscopy also provides for cerebrospinal fluid circulation obstruction treatment. The use of neuronavigation or stereotactic planning is particularly useful for the planning of an optimal surgical approach, helps to maintain anatomical orientation in distorted anatomy and facilitates haemostasis in case of intraoperative bleeding.

[Opportunistic infections in patients after complex therapy of cancer]. / Oportunní infekce mozku u pacientu po komplexní terapii nádorového onemocnení.

BACKGROUNDS: An opportunistic infection is an infection caused by pathogens, such as Toxoplasma gondii, that usually are not pathogenic in a healthy host but may cause an infection in immunocompromised patients. Although the most frequent cause of an opportunistic infection is immunodeficiency due to HIV infection, the immunodeficiency induced by anticancer treatment cannot be ignored. DESIGN: A 56-year old female patient after a comprehensive treatment of breast cancer underwent a stereotactic biopsy of MR-verified multiple brain lesions suspected to be of metastatic aetiology. The histology report unexpectedly concluded that the lesion was brain toxoplasmosis confirmed by detection of IgM specific antibody in cerebrospinal fluid. Immunology examination has proven a deficit of cell-mediated immunity. The symptoms (cephalea, cerebellar symptomatology with vertigo) and MR findings disappeared following 6-month treatment with a combination of pyrimethamin, sulfadiazin and leucovorin. CONCLUSION: Since neoplastic duplicities and brain lesions of non-neoplastic aetiology are found in about 11% of oncology patients, histological verification of aetiology of intracranial lesions is essential for targeted therapy of these patients. Our case of brain toxoplasmosis documents the role of opportunistic infections in differential diagnosis of brain lesions in patients who underwent anticancer treatment.

[Distant wounded glioma syndrome following stereotactic biopsy--a case review]. / Vzdálený syndrom zraneného gliomu po stereotaktické biopsii--kazuistika.

Postoperative haemorrhage is a threatening complication of both brain tumor resection and stereotactic biopsy. The paper describes rare case report of distant wounded glioma syndrome after stereotactic biopsy of glioblastoma, when small distant bleeding was proven in the tumor nodule distant from the original site of biopsy.

Pre-implant Heart Activity Differs in Responders and Non-responders to Vagal Nerve Stimulation Therapy in Epileptic Patients.

Vagal Nerve Stimulation (VNS) is used to treat patients with pharmacoresistant epilepsy. However, generally accepted tools to predict VNS response do not exist. Here we examined two heart activity measures - mean RR and pNN50 and their complex behavior during activation in pre-implant measurements. The ECG recordings of 73 patients (38 responders, 36 non-responders) were examined in a 30-sec floating window before (120 sec), during (2x120 sec), and after (120 sec) the hyperventilation by nose and mouth. The VNS response differentiation by pNN50 was significant (min p=0.01) in the hyperventilation by a nose with a noticeable descendant trend in nominal values. The mean RR was significant (p=0.01) in the rest after the hyperventilation by mouth but after an approximately 40-sec delay.Clinical Relevance- Our study shows that pNN50 and mean RR can be used to distinguish between VNS responders and non-responders. However, details of dynamic behavior showed how this ability varies in tested measurement segments.

Response to Vagal Stimulation by Heart-rate Features in Drug-resistant Epileptic Patients.

Vagal Nerve Stimulation (VNS) is an option in the treatment of drug-resistant epilepsy. However, approximately a quarter of VNS subjects does not respond to the therapy. In this retrospective study, we introduce heart-rate features to distinguish VNS responders and non-responders. Standard pre-implantation measurements of 66 patients were segmented in relation to specific stimuli (open/close eyes, photic stimulation, hyperventilation, and rests between). Median interbeat intervals were found for each segment and normalized (NMRR). Five NMRRs were significant; the strongest feature achieved significance with p=0.013 and AUC=0.66. Low mutual correlation and independence on EEG signals mean that presented features could be considered as an addition for models predicting VNS response using EEG.

[Primary brain tumor as a rare cause of acute subdural hematoma]. / Primární tumor mozku jako vzácná prícina akutního subdurálního hematomu.

The aim of the study is to present a case report describing patient, admitted for subdural haematoma located on temporal lobe base and brain convexity with intracerebral haematoma located in the depth of temporal lobe. Both haematomas were evacuated from burr holes. Histological analysis of tissue obtained during intracerebral haematoma aspiration has proven tumorous tissue consistent with anaplastic astrocytoma. Contrast enhanced MRI has confirmed the diagnosis and patient underwent tumor surgery. The study brings additional data to differential diagnosis of subdural haematoma, especially of non traumatic origin. When compared with meningiomas and metastatic tumors primary brain glioma is an exceptional cause of subdural haematoma of non traumatic origin.

Neuroendoscopy.

The discovery of optic bulb paved the way for the development of safe endoscopic systems not only with diagnostic ability, but also suitable for treatment. At the beginning of the 20th century, the first attempts to use an endoscope in the treatment of hydrocephalus have been made with encouraging results. Although the invention of an implantable shunt system slowed down the development of neuroendoscopy, the progress in fiberoptics and image processing has established the potential for the neuroendoscopy boom. Together with microneurosurgery, neuroendoscopy has established the concept of minimally invasive neurosurgery (Fig. 4, Ref. 16). Full Text (Free, PDF) www.bmj.sk.

[A history of the whole-body stereotactic navigation]. / Historie celotelové stereotaktické navigace.

The aim of the paper is to recall the invention of whole body stereotactic system employed under clinical conditions after previous model trials. Its prospectives have been overshadowed by the development of sophisticated modern navigation technique.