[Optimized assessment of the outcome in patients with radicular back pain of the lumbar spine. The modified NASS questionnaire]. / Bessere Verlaufsdokumentation bei Patienten mit lumboradikulären Schmerzsyndromen. Der modifizierte NASS-Fragebogen.

BACKGROUND: The purpose of the study was to present a reliable instrument with easy application to assess the outcome and improvement of therapy in patients with radicular symptoms of the lumbar spine. METHODS: Data from patients who underwent microdiscectomy because of lumbar radicular symptoms were collected and analyzed and interviews were performed using the well-known North American Spine Society (NASS) lumbar spine questionnaire (17 items) before and after the intervention. In addition patient data including comorbidities were collected. By calculating effect size (ES) and standardized response mean (SRM) for each item of the questionnaire, the questions with the highest change before and after the intervention could be selected. RESULTS: A total of 139 patients undergoing microdiscectomy for lumbar radicular symptoms due to a disc herniation were included in the analysis. Concerning the three dimensions pain, neurological symptoms and impairment of activities in daily life, the questions with best predictive value (high ES and SRM) were selected. According to their clinical relevance eight questions of the NASS questionnaire were finally selected for the short form. CONCLUSION: This short, significant and easy to use questionnaire is in our opinion a useful instrument to assess the course of patients with radicular back pain and especially to measure and monitor the outcome of therapeutic interventions, in addition to conventional clinical diagnostics and examinations. This novel instrument could be a useful tool for improving quality assurance in conventional and interventional pain management of these patients.

Inferior central sulcus: variations of anatomy and function on the example of the motor tongue area.

We wanted to define the position of the primary motor tongue area (MTA) by using functional magnetic resonance imaging (fMRI) to display the MTA in relation to the inferolateral segment of the central sulcus (CS). The anatomy of the inferolateral segment was analyzed in 24 healthy subjects, using the magnetization prepared rapid acquisition gradient echo sequence. The position of the MTA was defined in 11 subjects by using fMRI to identify the sites of maximal activation for each subject in relation to that subject's own CS. The MTA was then displayed in three orthogonal planes, and in lateral surface reformations. The inferolateral segment displayed two distinct curves in 33 of 48 (69%) hemispheres, three curves in 6%, and four curves in 23%. Significant paradigm correlated activations were found in every hemisphere. Thereof 89 local maxima were determined, with 84 (94%) located in the region of the CS. Sixty-seven (80%) of the 84 CS activations lay along the two lowest curves of the CS. In 86% of cases, activations situated in the middle and deep portion of the anterior bank of the CS were encompassed within the three axial sections centered on the cella media of the lateral ventricles. In conclusion, the variability of the inferior CS segment precluded the assignment of the MTA to a specific anatomic configuration. However, the position of the MTA could be approximated by the intersection between the CS and the three axial planes through, just above, and just below the cella media of the lateral ventricles.

Visualization of cranial nerves I-XII: value of 3D CISS and T2-weighted FSE sequences.

The aim of this study was to evaluate the sensitivity of the three-dimensional constructive interference of steady state (3D CISS) sequence (slice thickness 0.7 mm) and that of the T2-weighted fast spin echo (T2-weighted FSE) sequence (slice thickness 3 mm) for the visualization of all cranial nerves in their cisternal course. Twenty healthy volunteers were examined using the T2-weighted FSE and the 3D CISS sequences. Three observers evaluated independently the cranial nerves NI-NXII in their cisternal course. The rates for successful visualization of each nerve for 3D CISS (and for T2-weighted FSE in parentheses) were as follows: NI, NII, NV, NVII, NVIII 40 of 40 (40 of 40), NIII 40 of 40 (18 of 40), NIV 19 of 40 (3 of 40), NVI 39 of 40 (5 of 40), NIX, X, XI 40 of 40 (29 of 40), and NXII 40 of 40 (4 of 40). Most of the cranial nerves can be reliably assessed when using the 3D CISS and the T2-weighted FSE sequences. Increasing the spatial resolution when using the 3D CISS sequence increases the reliability of the identification of the cranial nerves NIII-NXII.

[Microsurgery of lumbar disc prolapse. Superior results of microsurgery as compared to standard- and percutaneous procedures (review of literature)]. / Mikrochirurgie lumbaler Bandscheibenvorfälle. Uberlegene Ergebnisse der Mikrochirurgie im Vergleich zu Standard- und perkutanen Verfahren (Literaturübersicht).

In a meta-analysis of 69 prospective and retrospective studies, we investigated the value of various surgical techniques in the treatment of lumbar disk herniations. This analysis includes standard diskectomy (5080 patients from nine series), microdiskectomy (5354/23), and comparison of both techniques (2494/10) and furthermore chemonucleolysis (2729/16), laser therapy (881/3), percutaneous nucleotomy (3506/18), comparisons of percutaneous techniques (942/5) with microdiskectomies (561/5) and standard diskectomies (1020/6). Outcomes were rated according to Macnab's criteria: I "excellent", II "good", III "improved", IV "same as before", V "worse", I/II "markedly improved", III "partially improved", IV/V "not improved", I-III "successful", and IV/V "unsuccessful". Results after microdiskectomy were "successful" more often (90% vs. 95%), "good/excellent" more often (82% vs. 73%), and patients left the hospital sooner than with standard diskectomy. Recurrence rates were comparable (4%). Results of both open techniques were clearly superior to those from any type of percutaneous treatment: chemonucleolysis und laser therapy were "successful" in 69% and 70% of cases respectively, with recurrence rates of 17% and 18%, endoscopic nucleotomy was "successful" in 84% of cases, and recurrence rate was 14%. Please ask the author for the reference database.

Detailed magnetic resonance imaging anatomy of the cisternal segment of the abducent nerve: Dorello's canal and neurovascular relationships and landmarks.

OBJECT: The goal of this study was to identify reliably the cisternal segment of the abducent nerve by using the three-dimensional Fourier transform constructive interference in steady-state (3-D CISS) magnetic resonance (MR) imaging sequence to define landmarks that assist in the identification of the abducent nerve on MR imaging and to describe the nerve's relationship to the anterior inferior cerebellar artery (AICA). METHODS: A total of 26 volunteers underwent 3-D CISS MR imaging, and 10 of these volunteers also underwent MR angiography in which a time-of-flight sequence was used to identify the facial colliculus, the abducent nerve and its apparent origin, Dorello's canal, and the AICA. The authors identified the abducent nerve with certainty in 96% of 3-D CISS sequences obtained in the axial and sagittal planes and in 94% obtained in the coronal plane. The nerve emerged from the pontomedullary sulcus in 94% of cases. The facial colliculus could always be identified, and Dorello's canal was identified in 94% of cases. In 76.6% of cases, the abducent nerve was seen to contact the AICA, which passed inferior to the nerve in 63.8% of cases and superior to it in 29.8%. CONCLUSIONS: The anatomical course of the abducent nerve and its relationship to the AICA and other blood vessels can be reliably identified using a 3-D CISS MR sequence with the facial colliculus and Dorello's canal serving as landmarks.

Localization of the motor hand area to a knob on the precentral gyrus. A new landmark.

Using functional magnetic resonance imaging (fMRI) we have evaluated the anatomical location of the motor hand area. The segment of the precentral gyrus that most often contained motor hand function was a knob-like structure, that is shaped like an omega or epsilon in the axial plane and like a hook in the sagittal plane. On the cortical surface of cadaver specimens this precentral knob corresponded precisely to the characteristic 'middle knee' of the central sulcus that has been described by various anatomists in the last century. We were then able to show that this knob is a reliable landmark for identifying the precentral gyrus directly. We therefore conclude that neural elements involved in motor hand function are located in a characteristic 'precentral knob' which is a reliable landmark for identifying the precentral gyrus under normal and pathological conditions. It faces and forms the 'middle knee' of the central sulcus, is located just at the cross point between the precentral sulcus and the central sulcus, and is therefore also visible on the cortical surface.

[Tumor surgery of the speech cortex in local anesthesia. Neuropsychological and neurophysiological monitoring during operations in the dominant hemisphere]. / Tumorchirurgie im Sprachkortex in Lokalanästhesie. Neuropsychologisches und neurophysiologisches Monitoring während Operationen in der dominanten Hirnhälfte.

We report on 30 cases where we have used cortical stimulation mapping to define the areas representing sensorimotor, language and speech functions under local anesthesia to facilitate resection of space-occupying lesions near these areas. Under the simplistic concept that Broca's area lies in the frontal operculum (inferior frontal gyrus) and that Wernicke's area is located in the posterior perisylvian area (superior temporal, angular and supramarginal gyri), we found language and speech function to be represented outside these areas in up to 4 stimulation sites of 15 patients. The results of cortical stimulation mapping were therefore essential to decide on the optimal access route to the lesions that were located subcortically and on the optimal resection plane in gliomas. After the limits of these areas and of the lesions had been established with stimulation mapping and with intrasurgical microscopic smear preparations, respectively, lesions were safely removed under continuous monitoring of sensorimotor, language and speech function. Immediately after surgery we encountered language and speech deficits in 9 patients (30%), which resolved completely in 5 and incompletely in 4 instances. Thus, language functions were normal in 26 patients (87%) at the end of the follow-up period. It is concluded that use of this technique allows safe and extensive resection of lesions that would otherwise have been considered hazardous to remove or inexcisable.

The central sulcal vein: a landmark for identification of the central sulcus using functional magnetic resonance imaging.

The authors evaluated the anatomical location of the central sulcus (CS) in 24 cerebral hemispheres (eight in which tumors were located centrally, 16 in controls) using: 1) classic anatomical landmarks seen on magnetic resonance (MR) imaging (24 hemispheres); 2) functional MR imaging (24 hemispheres); and 3) intraoperative electrical stimulation mapping (eight hemispheres). On MR imaging the CS was identified with certainty in 79% of hemispheres (four of eight in patients, 15 of 16 in controls). Functional MR imaging identified a parenchymal "motor hand area" in only 83% (20 of 24 hemispheres; five of eight in patients, 15 of 16 in controls); this area was located in the precentral gyrus in 16 (80%) of 20, additionally in the postcentral gyrus in 10 (50%) of 20, and exclusively in the postcentral gyrus in four (20%) of 20. In contrast, functional MR imaging detected one to three sulcal veins presumably draining blood from the adjacent motor hand area in 100% (24 of 24) of the hemispheres studied, and anatomical MR imaging and intraoperative mapping localized these veins in the CS. It is concluded that sulcal veins lying deep within the CS: 1) drain activated blood from the adjacent pre- or postcentral cortex during performance of a motor hand task; 2) can be identified easily with functional MR imaging; and 3) are an anatomical landmark for noninvasive identification of the CS and thus the sensorimotor strip. The detection of these veins provides a more consistent landmark than the detection of parenchymal motor areas by functional MR imaging; this technique may be used when classic anatomical landmarks fail to identify the sensorimotor strip.

Coaxial insulated bipolar electrode for monopolar and bipolar mapping of neural tissue: technical note with emphasis on the principles of intra-operative stimulation.

To facilitate use of various stimulation modes for intra-operative monitoring during neurosurgical procedures, we designed and produced a variable stimulation system that consists of a coaxial bipolar flush-tip insulated stimulation electrode, and a switch box to administer monopolar or bipolar stimulation through the same stimulation electrode. The electrode is composed of components that are readily available, so that its construction can be duplicated by others at minimal expense. For mapping of neural tissue during surgical procedures, we use the monopolar stimulation mode to identify relative large areas around the site of stimulation which are free of motor nerve fibres. The bipolar stimulation mode is most useful for precise localization of motor nerve fibres and in distinguishing motor from non-motor fibres.

[Function-controlled neurosurgery. Neurophysiologic and neuropsychological monitoring during surgery of the nervous system]. / Funktionskontrollierte Neurochirurgie. Neurophysiologisches und neuropsychologisches Monitoring während Operationen am Nervensystem.

Neuromonitoring of neural structures has become increasingly common during surgery near cortical areas representing sensorimotor and language function (epilepsia, tumors), in the brain stem and the spinal cord (tumors), near cranial nerves (cerebellopontine angle tumors, trigeminal neuralgia, hemifacial spasm), and in the cauda equina (tumors, tethered spinal cord). The technical spectrum to monitor these operations includes electrical cortical stimulation to evoke sensorimotor phenomena and language disturbances, electroneurography and -myography of the cauda equina, motor cranial nerves and nuclei, and somatosensory, motor and acoustic evoked potentials. The goals of intraoperative neuromonitoring are: (1) minimizing the risk of suffering neurological and neuropsychological injury as a result of surgery; (2) extending the surgical spectrum to lesions that have previously been considered inoperable or hazardous to operate upon; (3) intraoperative electrophysiological documentation that the goal of surgery has been achieved; (4) intraoperative basic research.

The mapping and continuous monitoring of the intrinsic motor nuclei during brain stem surgery.

A comprehensive technique was developed for continuous electrophysiological monitoring of intrinsic brain stem motor function during surgery to remove space-occupying lesions in the fourth ventricle and brain stem. The technique is analogous to that used during surgery in the cerebellopontine angle; motor nuclei and peripheral pontine fiber tracts of Cranial Nerves III-XII are identified by the electrical stimulation of structures in the operative field and the evaluation of the compound muscle action potentials recorded from the corresponding muscles of the head. Nerve function is monitored continuously by recording the ongoing electromyographic activity in these same muscles. Broadcasting electromyographic responses through a loudspeaker gives the surgeon immediate feedback on the status of the motor nuclei being monitored. Advantages of this technique include 1) the positive, objective identification of the nuclei and fiber tracts; 2) the continuous feedback on the status of these structures; 3) a safe approach through the fourth ventricle to the lesions in the brain stem; 4) the positive identification of the boundaries between the neoplasm and the motor structures of the rhomboid fossa; and 5) a warning to the surgeon of potentially harmful nerve manipulations (contact, dissection, transection) during surgery. After this technique was used in 16 consecutive operations to remove cavernomas (n = 9), gliomas (n = 4), and other types of tumors (n = 3), surgical and neurological results showed the method to be reliable and simple to perform.

Transcranial magnetic stimulation of the trigeminal nerve: intraoperative study on stimulation characteristics in man.

We studied responses from the masseter and nasalis muscles following magnetic stimulation (magStim) and compared these responses with those obtained by direct electrical stimulation of the trigeminal (NV) and facial (NVII) nerve near the root exit zone during microvascular decompression operations of NVII. We found that (1) magStim threshold to excite the nerve is high for NV and low for NVII; (2) excitation of all motor fibers is impossible for NV, and easy for NVII; (3) optimal coil placement is critical for NV, but not critical for NVII; and (4) between and within subjects, the excitation site is variable on NV, but stable on NVII. We estimated that the anatomical location of magStim to be either within or outside the cerebrospinal fluid for NV, and to be in the labyrinthine segment of the facial canal for NVII. Physical models explain and clinical lesion models support these differences found between NV and NVII.

Topography of the cortical motor hand area: prospective study with functional MR imaging and direct motor mapping at surgery.

PURPOSE: To localize the cortical motor hand area with functional magnetic resonance (MR) imaging and electrical stimulation at surgery and to detect changes due to central lesions. MATERIALS AND METHODS: Fast-gradient-echo and functional MR images of the brain were acquired in four healthy volunteers and six patients with tumors in the central region before, during, and after repetitive opening and closing of the hand. Open brain surgery was performed, and the exposed cortex was stimulated. RESULTS: At functional MR imaging, circumscribed changes in signal intensity that correlated in time with the task were seen in the central region of the contralateral brain. In the healthy volunteers, the area of change was spotlike and projected into the posterior bank of the precentral gyrus. In four of the six patients, this area was diffuse and projected into the precentral gyrus. The locations of the cortical hand area as determined with intrasurgical mapping and functional MR imaging were identical. CONCLUSION: Identification of the cortical area responsible for motor hand function was similar with functional MR imaging and with direct stimulation at surgery. A space-occupying lesion can change the cortical representation of motor hand function.

[The motor hand area. Noninvasive detection with functional MRI and surgical validation with cortical stimulation]. / Das motorische Handareal. Nichtinvasiver Nachweis mittels fMRT und operative Validierung mit kortikaler Stimulation.

In this study, activation of cortical sites by specific motor tasks (opening and closing of the hand) was examined by fMRI utilizing the blood-oxygen-level-dependent (BOLD) technique. fMRI was employed in five volunteers and in six patients with tumors in the vicinity of the central region. In the patients, the fMRI data and intraoperative cortical mapping were compared. Our results indicate good correlation of these two methods and that there are no significant differences in the localization of the motor hand area.

Intraoperative motor and sensory monitoring of the cauda equina.

A set of standard techniques to monitor the motor and sensory function of the cauda equina is proposed for surgery in the lumbosacral spinal canal for the release of a tethered cord or the removal of a neoplasm. Continuous loudspeaker-controlled recording of electromyographic activity in four leg muscles of both sides supplied the surgeon with immediate feedback on injury to any of the motor roots from the second lumbar to the fourth sacral segment. Continuous recording of tibial nerve somatosensory evoked potentials yielded information about the functional state of parts of the lumbosacral sensory pathways. Motor roots could be identified by electrical stimulation in the operating field with bipolar stimulation forceps and recording of compound muscle action potentials from the leg muscles. Sensory nerve roots could be identified by nerve root somatosensory evoked potentials recorded from the scalp after the electrical stimulation of the exposed nerve. This set-up is a combination of previously developed monitoring techniques and provides the surgeon with functional information: 1) continuous feedback on the state of the endangered motor and sensory function of the cauda equina; and 2) rapid anatomical identification of nerve roots and their distinction from fibrous or neoplastic structures.

Electrophysiological characterization of pre- and postoperative facial nerve function in patients with acoustic neuroma using electrical and magnetic stimulation techniques.

Facial nerve function was examined in patients who underwent posterior fossa surgery for unilateral acoustic neuroma. Examinations took place prior to surgery (n = 47 patients), early after surgery (0-12 days, n = 16 of 47 patients), and late after surgery (187-1505 days, n = 29 of 47 patients). Clinical signs of facial palsy were present to a variable extent in 13 of 47 patients before, in 12 of 16 patients early, and in 18 of 29 patients later after surgery. Electrophysiologically, the facial nerve was stimulated electrically at the stylomastoid fossa and magnetically at its proximal intracanalicular segment. In addition, the face-associated motor cortex was stimulated magnetically. In patients with facial palsy, any of these stimulation methods resulted in a decreased amplitude of the response in the nasalis muscle. The decrease showed a linear relationship to the clinical grade of palsy, pre- and postoperatively. Corticomuscular latencies remained unchanged. We conclude that: (i) the electrophysiological characteristics of facial nerve lesions due to compression by acoustic neuromas or due to a complication of neuroma removal are those of a purely axonal neuropathy; (ii) the three stimulation techniques have a similar diagnostic yield, thus making the use of all three of them redundant; and (iii) the electrophysiological techniques allowed no prediction of the final facial nerve function.

The effect of ketamine anesthetic induction on muscle responses to transcranial magnetic cortex stimulation studied in man.

In man, an anesthetic agent that induces surgical anesthesia with minimal influence on descending pyramidal tract activity remains to be found. Anesthesia with ketamine allows recording of stable compound muscle action potentials (CMAPs) to single transcranial magnetic stimulations of the motor cortex (CortStim) in monkeys. This report describes the findings in 5 patients, where CMAPs to CortStim were recorded from the right hypothenar during anesthesia induction with ketamine. The agent was injected intravenously every 90 s in 6 steps of 0.5 mg up to a maximum of 3 mg/kg body weight (BW). Surgical anesthesia was achieved after ketamine injection of 1.5 (n = 4 patients) or 2.0 mg/kg BW (n = 1). In the five individuals tested, CMAP amplitudes and latencies (mean; range) were 2.6 (1.6-5.8) mV and 22.8 (20.4-24.6) ms before induction, and 1.6 (0.3-4.7) mV and 23.5 (21.7-24.5) ms after administration of the maximum dose. The paired differences (mean +/- 1 S.D.) were 0.8 +/- 0.6 mV and 1.0 +/- 0.8 ms and were statistically not significant (n = 5, P = 0.1, Wilcoxon-test). With ketamine as a single anesthetic induction agent CMAPs to single CortStim remain easily recordable even in dosages higher than those necessary to induce surgical anesthesia. All other previously tested anesthetic agents suppress CMAPs to CortStim as soon as the patient is unconscious.

Transcranial magnetic stimulation of the facial nerve: intraoperative study on the effect of stimulus parameters on the excitation site in man.

Magnetic stimulation (magStim) of the intracranial facial nerve is performed in clinical and research settings, but the activation site is a matter of controversy. Latencies of nasalis muscle responses to magStim were, therefore, compared with those obtained by direct electrical stimulation of the facial nerve (a) at the root exit zone (REZ); (b) at the porus of the facial canal; and (c) in the stylomastoid fossa during microvascular decompression operations in the cerebellopontine angle (CPA). Measurements of latencies of the nasalis muscle response, obtained while the stimulating coil was placed over the parieto-occipital area of the scalp, indicated that it was the labryinthine segment of the facial canal, 5 to 16 mm distal to the CPA, that was activated. This would be in agreement with studies of physical models reported in the literature that showed (a) the strength of the electrical current generated by a magnetic field is particularly high close to a nerve foramen; and (b) excitation to magStim is most likely to occur where the induced electrical field changes rapidly over distance, i.e., at anatomical boundaries between media of high and low specific resistance. These characteristics are found at the end of the labyrinthine segment of the facial canal, where the facial nerve leaves the low-resistance cerebrospinal fluid and enters the high-resistance petrous bone. The site of neural excitation is robust and unaffected by stimulus intensity and current direction within a wide range, or by large changes in location of the coil.(ABSTRACT TRUNCATED AT 250 WORDS)