- Email: [email protected]
115. Health-related quality of life decreases with disease severity in German HSP patients
e48
Society Proceedings / Clinical Neurophysiology 120 (2009) e9–e88
BOLD-response in motor related areas during explicit and implicit aesthetic evaluation and elucidated the overall network involved in auditory temporal preferences. doi:10.1016/j.clinph.2008.07.111
113. Somatosensory evoked potentials elicited by lingual nerve stimulation—S. Dempewolf, M. Ahlborn, M. Lanz, S. Bunten, S. Happe (Klinikum Bremen-Ost, Klinische Neurophysiologie, Bremen, Germany) Objective: Lingual somatosensory evoked potentials are rarely used in clinical practice. For these rare investigations and particularly for forensic questions, however, a standardised method and normative data are essential. To our knowledge, only two groups have published normative data with small numbers of probands until today (Altenmüller et al., 1990 (n = 20), Maloney et al., 2000 (n = 5)). Methods: Twentyfive healthy subjects (48.3 ± 14.2 years, range 22–70; 16 female) were investigated. After unilateral tongue stimulation, potentials up to 50 ms via electrodes placed on the scalp (C5/ 6) with a frontocentral reference were recorded. The potential consisted of three main peaks within the first 50 ms, N1, P1 and N2, which were evaluated regarding latency, side difference and amplitude between P1 and N2. Results: See Table 1. Table 1
x SD x + 2.5SD x SD x + 2.5 SD
N1 (ms)
P1 (ms)
N2 (ms)
Amplitude (lV)
14.66 1.11 17.44 0.46 0.38 1.41
21.75 1.45 25.38 0.47 0.31 1.25
28.14 2.33 33.97 0.77 0.83 2.85
0.40 0.11 1.00 0.13 0.10 0.38
Conclusion: To date, this represents the largest group of healthy subjects evaluated for normative data of somatosensory evoked potentials following unilateral tongue stimulation. The collected normative data include for the first time the second negative peak which has not been evaluated before.
tain conditions are less impaired than one would expect. Improved movements can be triggered by external timing cues (Schenk et al., 2003), by sensory cues, such as auditory cues (Freeman et al., 1993) or visual cues (Cooke et al., 1978, Glickstein, 1993). It has been hypothesized that by timing movements externally the basal ganglia function for timing of movements is bypassed. In this work, we study the performance of PD patients on and off medication and normal control subjects in two types of movements: A ballistic punch against a punching bag and a controlled movement, in which the punch had to be stopped before the bag was touched. The patients were instructed to perform all the movements as fast as possible. The movements were recorded via a Zebris ultrasound device for a three-dimensional movement recording. Statistical data analysis was performed by student’s t-test and a random intercept model. Maximal angular velocity of the elbow joint was computed from the position signal of three markers (hand, elbow, shoulder) during both the controlled and the ballistic punch. Over all subjects, the ballistic movement was significantly faster than the controlled movement (p = 0.004). Only in the patient group were significant differences between the controlled and ballistic movements seen. In the control group, we did not measure any significant differences between the controlled and ballistic movements (Vball: 546 deg/s Vcontrol: 535 deg/s; p = 0.16). The ratio of Vball to Vcontrol of 1.02 underlines that the maximum speed of both the movements in normal control subjects was virtually the same. Patients in off-state performed the controlled movement significantly slower than the ballistic movement (Vball: 493 deg/s Vcontrol: 414 deg/s; p < 0.0001). Even in the on-state no change in the significance of Vball vs Vcontrol was seen, but the mean value of maximum speed in both the movement types increased considerably (Vball 526 deg/s Vcontrol: 475 deg/s; p < 0.0001). The ratio of maximum speed of both the movements reveals that the improvement is more pronounced in the controlled movement (ratio [on condition] Vball/Vcontrol = 1.11; ratio [off condition] Vball/ Vcontrol = 1.19). This finding was confirmed by the measurements of the second patient group that was treated with subthalamic nucleus deep brain stimulation for PD (ratio [on condition] Vball / Vcontrol = 1.14; ratio [off condition] Vball/ Vcontrol = 1.24). We conclude that the overall movements are facilitated effectively by dopaminergic treatment. The finding that the controlled movement is considerably slower than the simple ballistic movement in PD patients leads us to conclude that the slowness of movement is unequally more pronounced for complex as compared to simple movements in these patients.
References References Altenmüller E, Cornelius CP, Büttner UW. Somatosensory evoked potentials following tongue stimulation in normal subjects and patients with lesions of the aernt trigeminal system. Electroencephalogr Clin Neurophysiol 1990;77(6):403–15. Maloney SR, Bell WL, Shoaf SC, Blair D, Bastings EP, Good DC, et al. Measurement of lingual and palatine somatosensory evoked potentials. Clin Neurophysiol 2000;111(2):291–6.
Tolosa E et al. Lancet Neurol 2006;5:75–86. Benecke R et al. Brain 1987;110:361–79. Schenk T et al. Neuropsychologia 2003;41:783–94. Freeman JS et al. J Neurol Neurosurg Psychiatry 1993;56:1078–84. Cooke JD et al. Can J Neurol Sci 1978;5:413–5. Glickstein M. Trends Neurosci 1993;16:450–1.
doi:10.1016/j.clinph.2008.07.112 doi:10.1016/j.clinph.2008.07.113
114. Ballistic movements are less impaired in parkinson’s disease than controlled movements—K. Bötzel 1, J. Claassen 1, A. Crispin 2, S. Krafczyk 1, J. Levin 1 (1 Ludwig-Maximilians-Universität, Neurologische Klinik, München, Germany, 2 LMU München, IBE, München, Germany) Parkinson’s disease (PD) is a slowly progressing neurodegenerative disorder that leads to characteristic motor symptoms such as tremor, rigidity and bradykinesia (Tolosa et al., 2006). It has been shown that the basal ganglia play an important role in timing of movement (Benecke et al., 1987). However, the movements of PD patients under cer-
115. Health-related quality of life decreases with disease severity in German HSP patients—S. Klimpe 1, R. Schüle-Freyer 2, J. Kassubek 3, T. Klopstock 4, Z. Kohl 5, S. Klebe 6, S. Otto 7, S. Döhlinger 8, M. Dieterich 1, L. Schöls 2 (1 Johannes Gutenberg-Universität, Neurologische Klinik, Mainz, Germany, 2 Universitätsklinikum Tübingen, Zentrum für Neurologie, Tübingen, Germany, 3 Uniklinik Ulm, Neurologische Klinik, Ulm, Germany, 4 Klinikum der LMU München, Neurologische Klinik, München, Germany, 5 Uniklinik Regensburg, Neurologische Klinik, Regensburg, Germany, 6 Uniklinik Kiel, Neurologische Klinik, Kiel, Germany, 7 Uniklinik
Society Proceedings / Clinical Neurophysiology 120 (2009) e9–e88
e49
Bochum, Neurologische Klinik, Bochum, Germany, 8 Abteilung für Neurodegeneration, Zentrum für Neurologische Medizin, Göttingen, Germany)
Lübeck, Germany, 2 University of Luebeck, Institute for Robotics and Cognitive Systems, Lübeck, Germany, 3 University of Luebeck, Institute for Signal Processing, Lübeck, Germany)
Background: The Hereditary Spastic Paraplegias (HSPs) comprise a clinically and genetically heterogeneous group of neurodegenerative disorders characterised by a slowly progressive spastic gait disorder. Clinically, ‘‘pure’’ and ‘‘complicated’’ forms are distinguished. The impact of HSP on the quality of life is not known so far. Therefore, we assessed the health-related quality of life with the Short-Form 36 (SF-36) quality of life questionnaire in a sample of HSP patients of the GeNeMove network project. Patients and methods: 123 patients with HSP (47.2% women, mean age 47.4; 16–80 years) participating in the GeNeMove project were included. Inheritance was predominantly autosomal-dominant (61.0%), 34.1% had mutations in the most common SPG4 (‘‘Spastin’’) gene. Patients were examined using the standardized Spastic Paraplegia Rating Scale (SPRS, range 0–52 points, Schüle et al., 2006). The SF-36 questionnaires were filled in during regular visits. The SF-36 consists of 36 questions concerning the different aspects of health related quality of life (QoL). Answers are computed in eight scales representing distinct fields of QoL. These subscales are again computed in two summary scores, the mental and physical component scores (MCS and PCS). These scores simplify the interpretation of results and have been shown to be a reliable instrument. MCS and PCS normal values are 50 (SD 10) with higher scores indicating positive results. Results: 68.3% of the patients had a clinically ‘‘pure’’ form of HSP. Age of onset was 30.6 years (SD 15.9, 0–66). The mean SPRS score was 18.0 (SD 9.7, 0–42) and differed significantly (p < 0.000) between ‘‘pure’’ (15.8, SD 8.5) and ‘‘complicated’’ (22.6, SD 10.4) HSP. PCS (35.1; SD 11.5) was significantly (p < 0.000) lower than MCS (42.7; SD 12.6). No significant differences between ‘‘pure’’ and ‘‘complicated’’ HSP were found between MCS and PCS. High SPRS scores correlated significantly with low PCS (r = .66; p < 0.01) and MCS (r = .42; p < 0.01) scores. Discussion: German HSP patients present a wide spectrum of disease severity which can be demonstrated by the broad range of SPRS results between 0 and 42 points. The influence of HSP on QoL was different between PCS and MCS. As expected, patients were more affected by the physical restraints of their disease resulting in low PCS scores. In contrast, the mental affection in the MCS was significantly less severe. Nevertheless, both the physical and mental health decrease with higher SPRS scores. Compared to a sample of 576 German MS patients (Haupts et al., 2003), the HSP patients scored lower on the PCS (MS-patients: 43.9; SD 9.9) but were similar to a subgroup of 62 more affected patients with a EDSS 4.0 (36.5; SD9.0). In contrast, MCS results were comparable between HSP and MS patients. Conclusion: Health related QoL is impaired in German HSP patients depending on disease severity. This is more pronounced concerning physical aspects, whereas the mental aspects seem to be more preserved. The reduced QoL is comparable to more disabled MS patients. This study was conducted within the BMBF granted GeNeMove project. We thank the Tom-Wahlig-Stiftung and the Selbsthilfegruppe for HSP-Patients for supporting the project.
Introduction: Severe motoric symptoms in parkinson’s disease arise from the loss of dopaminergic input into the striatum. The striatal efferent nuclei are thus affected by a lack of GABAergic input. Deep brain stimulation (DBS) in the subthalamic nucleus (STN) seems to counterbalance this effect by a hitherto unknown molecular mechanism. Based on the hypothesis that high frequency electrical stimulation may have an effect on neurotransmitter release in the local environment of the stimulation electrode we established an in vivo rat model allowing for simultaneous and collocated high frequency stimulation and microdialysis in freely moving rats. Methods: Using standard stereotaxic techniques we implanted a double tube guiding cannula right above the corresponding target nucleus and fixed it on the skull for permanent disposition. After a 7-day period of recovery we inserted a microdialysis probe and a stimulation electrode into the guiding cannula such that the tips of the probes were placed in the center of the target nucleus. The electrode surface was pointing to the microdialysis membrane with a distance smaller than 1 mm. Thus we were able to sample neurotransmitter outflow during the periods of electrical high frequency stimulation in different target nuclei. After the experiment we removed the brain and examined the accuracy of the probe placement using histological slices of the rat brain. Problem: Though leading to promising results in the rat caudate nucleus with a targeting accuracy of 100% we had to face problems with the placement of stimulation electrode and microdialysis membrane into the small sized rat STN using standard stereotaxic techniques. Solution: We employed a new robot-assisted neuronavigation framework for small animal stereotaxy. The robotized spherical assistant for stereotaxic surgery (SASSU) allows automated, precise and repeatible implantation of probes into the brain. It is controlled by a navigation software based on coronal slices of the rat brain. Therefore, software assisted preoperative planning could be easily performed using the software. Bregma and Lambda were used as landmarks for the registration of the rat skull like it is done with the standard stereotaxic methods. Software parameter definition took place according to the surgical workflow. The SASSU step size and velocity were adjusted on demand. By definition of five different parameters we were able to guide a microdialysis probe and a stimulation electrode near together into the rat STN with any specified angle of entry and a positioning accuracy smaller than 45 lm. The SASSU therefore provides a new stereotaxic tool for target optimization in DBS of the rat STN.
doi:10.1016/j.clinph.2008.07.114
116. Robot assisted stereotaxic targeting for STN DBS in the rat brain—S. Löffler 1, L. Ramrath 2, U.G. Hofmann 3, A. Schweikard 2, A. Moser 1 (1 University of Luebeck, Department of Neurology,
doi:10.1016/j.clinph.2008.07.115
117. Noninvasive quantification of intracerebral GABA by 1H-MRS – How reproducible are the results?—T. Hammen 1, W. Bogner 2, A. Stadlbauer 3, M. Doelken 4, A. Doerfler 4, H. Stefan 1 (1 Universität Erlangen, Klinik für Neurologie, Epilepsiezentrum Erlangen, Erlangen, Germany, 2 AKH Wien, MR-Exzellenszentrum, Wien, Austria, 3 Universität Erlangen, Klinik für Neurochirurgie, Erlangen, Germany, 4 Universität Erlangen, Klinik für Neuroradiologie, Erlangen, Germany) Purpose: Gamma-aminobutyric acid (GABA) is an important inhibitatory neurotransmitter in human brain with anticonvulsive character. Because of an increased interest in GABA metabolism we tested the reliability of a special editing sequence which allows
Society Proceedings / Clinical Neurophysiology 120 (2009) e9–e88
BOLD-response in motor related areas during explicit and implicit aesthetic evaluation and elucidated the overall network involved in auditory temporal preferences. doi:10.1016/j.clinph.2008.07.111
113. Somatosensory evoked potentials elicited by lingual nerve stimulation—S. Dempewolf, M. Ahlborn, M. Lanz, S. Bunten, S. Happe (Klinikum Bremen-Ost, Klinische Neurophysiologie, Bremen, Germany) Objective: Lingual somatosensory evoked potentials are rarely used in clinical practice. For these rare investigations and particularly for forensic questions, however, a standardised method and normative data are essential. To our knowledge, only two groups have published normative data with small numbers of probands until today (Altenmüller et al., 1990 (n = 20), Maloney et al., 2000 (n = 5)). Methods: Twentyfive healthy subjects (48.3 ± 14.2 years, range 22–70; 16 female) were investigated. After unilateral tongue stimulation, potentials up to 50 ms via electrodes placed on the scalp (C5/ 6) with a frontocentral reference were recorded. The potential consisted of three main peaks within the first 50 ms, N1, P1 and N2, which were evaluated regarding latency, side difference and amplitude between P1 and N2. Results: See Table 1. Table 1
x SD x + 2.5SD x SD x + 2.5 SD
N1 (ms)
P1 (ms)
N2 (ms)
Amplitude (lV)
14.66 1.11 17.44 0.46 0.38 1.41
21.75 1.45 25.38 0.47 0.31 1.25
28.14 2.33 33.97 0.77 0.83 2.85
0.40 0.11 1.00 0.13 0.10 0.38
Conclusion: To date, this represents the largest group of healthy subjects evaluated for normative data of somatosensory evoked potentials following unilateral tongue stimulation. The collected normative data include for the first time the second negative peak which has not been evaluated before.
tain conditions are less impaired than one would expect. Improved movements can be triggered by external timing cues (Schenk et al., 2003), by sensory cues, such as auditory cues (Freeman et al., 1993) or visual cues (Cooke et al., 1978, Glickstein, 1993). It has been hypothesized that by timing movements externally the basal ganglia function for timing of movements is bypassed. In this work, we study the performance of PD patients on and off medication and normal control subjects in two types of movements: A ballistic punch against a punching bag and a controlled movement, in which the punch had to be stopped before the bag was touched. The patients were instructed to perform all the movements as fast as possible. The movements were recorded via a Zebris ultrasound device for a three-dimensional movement recording. Statistical data analysis was performed by student’s t-test and a random intercept model. Maximal angular velocity of the elbow joint was computed from the position signal of three markers (hand, elbow, shoulder) during both the controlled and the ballistic punch. Over all subjects, the ballistic movement was significantly faster than the controlled movement (p = 0.004). Only in the patient group were significant differences between the controlled and ballistic movements seen. In the control group, we did not measure any significant differences between the controlled and ballistic movements (Vball: 546 deg/s Vcontrol: 535 deg/s; p = 0.16). The ratio of Vball to Vcontrol of 1.02 underlines that the maximum speed of both the movements in normal control subjects was virtually the same. Patients in off-state performed the controlled movement significantly slower than the ballistic movement (Vball: 493 deg/s Vcontrol: 414 deg/s; p < 0.0001). Even in the on-state no change in the significance of Vball vs Vcontrol was seen, but the mean value of maximum speed in both the movement types increased considerably (Vball 526 deg/s Vcontrol: 475 deg/s; p < 0.0001). The ratio of maximum speed of both the movements reveals that the improvement is more pronounced in the controlled movement (ratio [on condition] Vball/Vcontrol = 1.11; ratio [off condition] Vball/ Vcontrol = 1.19). This finding was confirmed by the measurements of the second patient group that was treated with subthalamic nucleus deep brain stimulation for PD (ratio [on condition] Vball / Vcontrol = 1.14; ratio [off condition] Vball/ Vcontrol = 1.24). We conclude that the overall movements are facilitated effectively by dopaminergic treatment. The finding that the controlled movement is considerably slower than the simple ballistic movement in PD patients leads us to conclude that the slowness of movement is unequally more pronounced for complex as compared to simple movements in these patients.
References References Altenmüller E, Cornelius CP, Büttner UW. Somatosensory evoked potentials following tongue stimulation in normal subjects and patients with lesions of the aernt trigeminal system. Electroencephalogr Clin Neurophysiol 1990;77(6):403–15. Maloney SR, Bell WL, Shoaf SC, Blair D, Bastings EP, Good DC, et al. Measurement of lingual and palatine somatosensory evoked potentials. Clin Neurophysiol 2000;111(2):291–6.
Tolosa E et al. Lancet Neurol 2006;5:75–86. Benecke R et al. Brain 1987;110:361–79. Schenk T et al. Neuropsychologia 2003;41:783–94. Freeman JS et al. J Neurol Neurosurg Psychiatry 1993;56:1078–84. Cooke JD et al. Can J Neurol Sci 1978;5:413–5. Glickstein M. Trends Neurosci 1993;16:450–1.
doi:10.1016/j.clinph.2008.07.112 doi:10.1016/j.clinph.2008.07.113
114. Ballistic movements are less impaired in parkinson’s disease than controlled movements—K. Bötzel 1, J. Claassen 1, A. Crispin 2, S. Krafczyk 1, J. Levin 1 (1 Ludwig-Maximilians-Universität, Neurologische Klinik, München, Germany, 2 LMU München, IBE, München, Germany) Parkinson’s disease (PD) is a slowly progressing neurodegenerative disorder that leads to characteristic motor symptoms such as tremor, rigidity and bradykinesia (Tolosa et al., 2006). It has been shown that the basal ganglia play an important role in timing of movement (Benecke et al., 1987). However, the movements of PD patients under cer-
115. Health-related quality of life decreases with disease severity in German HSP patients—S. Klimpe 1, R. Schüle-Freyer 2, J. Kassubek 3, T. Klopstock 4, Z. Kohl 5, S. Klebe 6, S. Otto 7, S. Döhlinger 8, M. Dieterich 1, L. Schöls 2 (1 Johannes Gutenberg-Universität, Neurologische Klinik, Mainz, Germany, 2 Universitätsklinikum Tübingen, Zentrum für Neurologie, Tübingen, Germany, 3 Uniklinik Ulm, Neurologische Klinik, Ulm, Germany, 4 Klinikum der LMU München, Neurologische Klinik, München, Germany, 5 Uniklinik Regensburg, Neurologische Klinik, Regensburg, Germany, 6 Uniklinik Kiel, Neurologische Klinik, Kiel, Germany, 7 Uniklinik
Society Proceedings / Clinical Neurophysiology 120 (2009) e9–e88
e49
Bochum, Neurologische Klinik, Bochum, Germany, 8 Abteilung für Neurodegeneration, Zentrum für Neurologische Medizin, Göttingen, Germany)
Lübeck, Germany, 2 University of Luebeck, Institute for Robotics and Cognitive Systems, Lübeck, Germany, 3 University of Luebeck, Institute for Signal Processing, Lübeck, Germany)
Background: The Hereditary Spastic Paraplegias (HSPs) comprise a clinically and genetically heterogeneous group of neurodegenerative disorders characterised by a slowly progressive spastic gait disorder. Clinically, ‘‘pure’’ and ‘‘complicated’’ forms are distinguished. The impact of HSP on the quality of life is not known so far. Therefore, we assessed the health-related quality of life with the Short-Form 36 (SF-36) quality of life questionnaire in a sample of HSP patients of the GeNeMove network project. Patients and methods: 123 patients with HSP (47.2% women, mean age 47.4; 16–80 years) participating in the GeNeMove project were included. Inheritance was predominantly autosomal-dominant (61.0%), 34.1% had mutations in the most common SPG4 (‘‘Spastin’’) gene. Patients were examined using the standardized Spastic Paraplegia Rating Scale (SPRS, range 0–52 points, Schüle et al., 2006). The SF-36 questionnaires were filled in during regular visits. The SF-36 consists of 36 questions concerning the different aspects of health related quality of life (QoL). Answers are computed in eight scales representing distinct fields of QoL. These subscales are again computed in two summary scores, the mental and physical component scores (MCS and PCS). These scores simplify the interpretation of results and have been shown to be a reliable instrument. MCS and PCS normal values are 50 (SD 10) with higher scores indicating positive results. Results: 68.3% of the patients had a clinically ‘‘pure’’ form of HSP. Age of onset was 30.6 years (SD 15.9, 0–66). The mean SPRS score was 18.0 (SD 9.7, 0–42) and differed significantly (p < 0.000) between ‘‘pure’’ (15.8, SD 8.5) and ‘‘complicated’’ (22.6, SD 10.4) HSP. PCS (35.1; SD 11.5) was significantly (p < 0.000) lower than MCS (42.7; SD 12.6). No significant differences between ‘‘pure’’ and ‘‘complicated’’ HSP were found between MCS and PCS. High SPRS scores correlated significantly with low PCS (r = .66; p < 0.01) and MCS (r = .42; p < 0.01) scores. Discussion: German HSP patients present a wide spectrum of disease severity which can be demonstrated by the broad range of SPRS results between 0 and 42 points. The influence of HSP on QoL was different between PCS and MCS. As expected, patients were more affected by the physical restraints of their disease resulting in low PCS scores. In contrast, the mental affection in the MCS was significantly less severe. Nevertheless, both the physical and mental health decrease with higher SPRS scores. Compared to a sample of 576 German MS patients (Haupts et al., 2003), the HSP patients scored lower on the PCS (MS-patients: 43.9; SD 9.9) but were similar to a subgroup of 62 more affected patients with a EDSS 4.0 (36.5; SD9.0). In contrast, MCS results were comparable between HSP and MS patients. Conclusion: Health related QoL is impaired in German HSP patients depending on disease severity. This is more pronounced concerning physical aspects, whereas the mental aspects seem to be more preserved. The reduced QoL is comparable to more disabled MS patients. This study was conducted within the BMBF granted GeNeMove project. We thank the Tom-Wahlig-Stiftung and the Selbsthilfegruppe for HSP-Patients for supporting the project.
Introduction: Severe motoric symptoms in parkinson’s disease arise from the loss of dopaminergic input into the striatum. The striatal efferent nuclei are thus affected by a lack of GABAergic input. Deep brain stimulation (DBS) in the subthalamic nucleus (STN) seems to counterbalance this effect by a hitherto unknown molecular mechanism. Based on the hypothesis that high frequency electrical stimulation may have an effect on neurotransmitter release in the local environment of the stimulation electrode we established an in vivo rat model allowing for simultaneous and collocated high frequency stimulation and microdialysis in freely moving rats. Methods: Using standard stereotaxic techniques we implanted a double tube guiding cannula right above the corresponding target nucleus and fixed it on the skull for permanent disposition. After a 7-day period of recovery we inserted a microdialysis probe and a stimulation electrode into the guiding cannula such that the tips of the probes were placed in the center of the target nucleus. The electrode surface was pointing to the microdialysis membrane with a distance smaller than 1 mm. Thus we were able to sample neurotransmitter outflow during the periods of electrical high frequency stimulation in different target nuclei. After the experiment we removed the brain and examined the accuracy of the probe placement using histological slices of the rat brain. Problem: Though leading to promising results in the rat caudate nucleus with a targeting accuracy of 100% we had to face problems with the placement of stimulation electrode and microdialysis membrane into the small sized rat STN using standard stereotaxic techniques. Solution: We employed a new robot-assisted neuronavigation framework for small animal stereotaxy. The robotized spherical assistant for stereotaxic surgery (SASSU) allows automated, precise and repeatible implantation of probes into the brain. It is controlled by a navigation software based on coronal slices of the rat brain. Therefore, software assisted preoperative planning could be easily performed using the software. Bregma and Lambda were used as landmarks for the registration of the rat skull like it is done with the standard stereotaxic methods. Software parameter definition took place according to the surgical workflow. The SASSU step size and velocity were adjusted on demand. By definition of five different parameters we were able to guide a microdialysis probe and a stimulation electrode near together into the rat STN with any specified angle of entry and a positioning accuracy smaller than 45 lm. The SASSU therefore provides a new stereotaxic tool for target optimization in DBS of the rat STN.
doi:10.1016/j.clinph.2008.07.114
116. Robot assisted stereotaxic targeting for STN DBS in the rat brain—S. Löffler 1, L. Ramrath 2, U.G. Hofmann 3, A. Schweikard 2, A. Moser 1 (1 University of Luebeck, Department of Neurology,
doi:10.1016/j.clinph.2008.07.115
117. Noninvasive quantification of intracerebral GABA by 1H-MRS – How reproducible are the results?—T. Hammen 1, W. Bogner 2, A. Stadlbauer 3, M. Doelken 4, A. Doerfler 4, H. Stefan 1 (1 Universität Erlangen, Klinik für Neurologie, Epilepsiezentrum Erlangen, Erlangen, Germany, 2 AKH Wien, MR-Exzellenszentrum, Wien, Austria, 3 Universität Erlangen, Klinik für Neurochirurgie, Erlangen, Germany, 4 Universität Erlangen, Klinik für Neuroradiologie, Erlangen, Germany) Purpose: Gamma-aminobutyric acid (GABA) is an important inhibitatory neurotransmitter in human brain with anticonvulsive character. Because of an increased interest in GABA metabolism we tested the reliability of a special editing sequence which allows