[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.

Transcranial magnetic stimulation excites the labyrinthine segment of the facial nerve: an intraoperative electrophysiological study in man.

The site where transcranial magnetic stimulation (magStim) depolarizes the facial nerve was investigated in 6 patients who underwent surgery of the cerebellopontine angle (CPA). The facial nerve was stimulated (1) magnetically prior to craniotomy, (2) electrically near the brainstem (elREZ), (3) at the exit from the CPA into the facial canal (elPorus), and (4) in the stylomastoid fossa (elStylo). The range of latency differences (delta) of compound muscle action potentials (CMAPs) recorded from the ipsilateral mentalis muscle were as follows: delta elREZ-magStim: +0.5 to +1.1 ms (P less than or equal to 0.03, Wilcoxon test); delta elPorus-magStim: +0.2 to +0.5 ms (P less than or equal to 0.03); delta elStylo-magStim: +0.8 to +1.0 ms (P less than or equal to 0.03). On the basis of anatomical data and a facial nerve conduction velocity of 33-46 m/s in these patients, it was concluded that transcranial magnetic stimuli depolarized the facial nerve at a location 10-15 mm distal to its entrance into the facial canal. This corresponds to the end of the labyrinthine segment of the facial nerve, i.e. the transit zone where the nerve ceases to be surrounded by cerebrospinal fluid (CSF) with its high electrical conductivity and enters the high-resistance tissue of the petrous bone.

The excitation site of the trigeminal nerve to transcranial magnetic stimulation varies and lies proximal or distal to the foramen ovale: an intraoperative electrophysiological study in man.

The excitation site of the trigeminal nerve using transcranial magnetic stimulation (magStim) was analyzed in 5 patients in whom the trigeminal nerve was surgically exposed in the posterior fossa during microvascular decompression of the facial nerve for hemifacial spasm. The trigeminal nerve was stimulated (1) magnetically immediately prior to craniotomy, and (2) electrically near the root exit zone (elREZ) of the nerve from the brainstem. Mean latency differences (delta) of masseter compound muscle action potentials (CMAPs) (delta elREZ minus magStim) were 0.7 (range: +0.3 to +1.3) ms (P less than or equal to 0.05, Wilcoxon-test). From these results, an analysis of anatomical data, and using a trigeminal nerve conduction velocity (NCV) of 50 m/s as reported in the literature, the following conclusions were drawn: the excitation site to magStim (1) is variable among individuals, (2) is located 3.4 (1.6-6.5) cm distal to the trigeminal REZ, and (3) which corresponds to segments of the nerve that are located either within or outside the cerebrospinal fluid (CSF), either proximal or distal to the foramen ovale. These findings are in contrast to those we obtained in a previous study of the facial nerve in which the excitation site was found to be constant among subjects and restricted to the location on the nerve where it exists the high conductivity CSF to enter the high-resistance petrous bone.

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.

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.

Orthodromic (intra/extracranial) neurography to monitor facial nerve function intraoperatively.

This report introduces the technique of orthodromic neurography for monitoring of facial nerve function during operation in the cerebellopontine angle. By stimulation of the intracisternal segment of the facial nerve, a compound nerve action potential with amplitudes of 15 to 480 microV can be recorded extracranially from the nerve near the stylomastoid foramen after 0.95 to 2.27 ms. Usually there is no need for signal averaging, and the method is independent of the effect of muscle relaxants. With the use of the same electrophysiological equipment as for evoked potential neuromonitoring, immediate and repeated localization of the facial nerve and its discrimination from the trigeminal and the lower cranial nerves during nerve preparation within the tumor capsule is possible.

Influence of some anesthetic agents on muscle responses to transcranial magnetic cortex stimulation: a pilot study in humans.

The effects of some commonly used intravenous and inhalational anesthetic agents on the motor evoked responses to transcranial magnetic cortex stimulation were assessed in 17 subjects. Compound motor action potentials (CMAPs) of the abductor digiti minimi muscle were recorded. Baseline values (12 stimulations/subject) were established before anesthesia was induced with a single agent administered in steps up to a maximal dose (MaxDose). Cortical stimulation was performed and depth of anesthesia was assessed according to Guedel after each dose. A common feature was the marked intra- and interindividual variability of baseline values of CMAPs in those patients not premedicated, those premedicated, and the anesthetized patients. The average amplitude of CMAPs was related to the depth of anesthesia in a given subject, whereas onset latencies of CMAPs did not systematically change. CMAPs were markedly reduced or abolished after administration of potent sedative drugs such as midazolam (MaxDose, 0.4 mg/kg body weight), pentothal (MaxDose, 8 mg/kg), propofol (MaxDose, 2 mg/kg), and isoflurane (MaxDose, 1.9 and 3.7 vol %), as soon as patients reached Stage II and Stage III anesthesia. When fentanyl (MaxDose, 8 micrograms/kg) or nitrous oxide (MaxDose, 79%) was used, the subjects reached Stages I and II, but not Stage III. With these drugs, reliable recording of CMAPs was possible even with the maximal administered dose.

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.

Management of obstructive hydrocephalus secondary to posterior fossa tumors by steroids and subcutaneous ventricular catheter reservoir.

In 61 patients (38 adults and 23 children) with surgically treatable tumors of the posterior fossa and obstructive hydrocephalus the following treatment for hydrocephalus was employed: a high dose of steroids was given after diagnosis; a frontal ventricular catheter with a subcutaneous fluid reservoir (Rickham) was inserted within 2 to 5 days; a temporary external ventricular drainage system was attached to the reservoir if, despite the steroids, intracranial pressure was over 30 cm H2O; and tumor excision was performed within 5 days to reopen the cerebrospinal fluid (CSF) pathways. In view of the wide range of potential complications, it was decided not to use a shunt before craniotomy. A shunt was inserted only if the CSF pathways remained obstructed after tumor removal. With this regimen, 93% of all patients (100% of the adults and 83% of the children) were shunt-free after the operation, without fatal complications. The infection rate was 4.9%. It was concluded that the severity of symptoms of raised intracranial pressure from hydrocephalus, the intraventricular pressure, and the size or location of the tumor prior to surgery do not have prognostic value as to which patients will require a shunt after surgery.

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.

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.

Intercostolumbar spinal nerve anastomosis. An experimental study in dogs.

End-to-end anastomoses were done between the motor roots of T12 and T13 intercostal nerves and the ipsilateral transsected L1 lumbar nerve in four dogs. In three of the dogs, the clinical and electrophysiologic findings showed functional viability of the intercostolumbar anastomosis 3.5 months after the anastomosis was done. The method may be practical for reinnervating an injured lumbar nerve with two intercostal nerves or to bypass a spinal cord lesion.

[Mapping in tumor surgery of the central region]. / Mapping bei Tumoroperationen in der Zentralregion.

A prerequisite for successful operations of the central area is the exact pre- and intraoperative localization of the motor strip and the pyramidal tract. The craniocerebral landmarks--the coronal suture and bregma--and the central anatomy in the CT and the MRI favors their localization. According to the anatomical variations and the displacement of the brain by the lesion, these landmarks are not very reliable in identifying the central region in all cases. A safe intraoperative localization of the motor strip is possible with the combination of electrical cortical stimulation and recording of somatosensory evoked potentials. With these methods the results of operations of central lesions are good and the risk of severe postoperative morbidity is low.

[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.

[Head injuries in childhood caused by skiing and their optimal prevention]. / Kindliche Kopfverletzungen beim Skifahren und ihre optimale Prophylaxe.

During the last three skiing seasons we have treated a total of 105 children in our clinical wards for skull-brain injuries caused by skiing accidents. 25 of these cases (25.2%) were operated on, mostly because of a depressed fracture (92%) with or without brain lesion/bleeding, which the children incurred by colliding with various obstacles. Uncontrolled excessive speed and careless skiing methods are the main reasons for these injuries. However, the responsibility for the increasing number of skisport-connected skull-brain injuries does not lie with the children alone, but more so with us grown-ups, i.e. the parents, teachers and physicians, as long as we do not preach and emphatically insist on the implementation of indirect and direct specific measures of accident prevention. Based on an analysis of typical injuries and their many causes we come to the conclusion that, aside from the usual precautions, only one simple, sensible and effective prevention of skull-brain injuries is feasible, namely the "protection helmet". Similar to the existing crash-helmet law for motorcylists and just like for the professional skiracers, whom the children try to imitate more and more with regard to style and speed, we earnestly urge legislation to make the wearing of a protective helmet compulsory for all skiers up to 17 years of age.

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.

Accuracy of high resolution computed tomography in direct diagnosis of cerebral aneurysms.

With high resolution computed tomography (CT) of the skull, performing rapid series of 1.5 mm slices during an intravenous bolus injection of contrast medium, an angiography-like image (angio-CT) of the basal cerebral arteries can be obtained. From 76 consecutive angiographically or autopsy-verified cerebral aneurysms of various size down to 3 mm in diameter, 74 (97.4%) were shown up by the angio-CT. One ruptured and one incidental aneurysm escaped CT visualization. Besides the correct localization of the aneurysms, angio-CT provides information concerning the size and main direction of the aneurysms and yields, in addition, a coronal view of the aneurysms and their surrounding structures. Pitfalls for mis-diagnosis can be the following: Aneurysms of below 5 mm in diameter, located at the supraclinoid part of the carotid artery, multiple or non-ruptured aneurysms, bony or movement artefacts, poorly contrasted vessels due to wrong injection technique of contrast medium or vasospasm, and incorrect interpretation.