Surface and boney landmarks for sacral neuromodulation: a cadaveric study.

INTRODUCTION AND HYPOTHESIS: Standard external landmarks have been suggested as a guide for in-office percutaneous nerve evaluation (PNE), but validity of these landmarks has not been assessed. Our objective was to determine whether the standard 9 cm from the tip of the coccyx indicates the position of the S3 sacral foramen and whether other boney landmarks and measurements improved positioning. METHODS: Measurements and distances between external boney landmarks were obtained in 22 embalmed cadavers. Spinal needles were placed 9 cm superior to the coccyx and 2 cm lateral to midline bilaterally. After dissection, internal measurements relating to sacral length, position of S3, and location of the needle in relation to S3 were recorded. Correlations among measured variables were assessed using descriptive statistics. RESULTS: Mean distance from the tip of coccyx to S3 was 9.26 cm (±0.84), from S3 to midline 2.30 cm (±0.2); from needle to S3 1.25 cm, and needle placement was as likely to be placed above or below S3; and S2-S3 and S3-S4 interforamenal distance 1.48 cm (±0.30) and 1.48 cm (±0.24), respectively. Mean distance from S3 to sacroiliac joint (SIJ) was shorter than S2 to SIJ. All associations between external measurements and length from tip of coccyx to S3 were not significant. CONCLUSION: A distance 9 cm from the tip of the coccyx is a reasonable starting landmark for in-office blind PNE. However, given the variability in coccyx length, caution should be taken; also, sensory-motor response is necessary to confirm proper placement.

Morphological changes of the in vitro cervical vertebral canal and its cast form during flexion, extension, and lateral bending.

OBJECTIVE: The purpose of this study was to investigate and measure morphological changes in the vertebral canal and its cast form at the level of the cervical spine in vitro during flexion, extension, and lateral bending in cadaver specimens. METHODS: The morphological changes of vertebral canal and its contents were investigated and measured during experimental flexion, extension, and lateral bending of the cervical spine with 10 fresh specimens (Chinese); the cross-sections and sagittal diameters were also measured by pouring liquid wax into the intervertebral canal. RESULTS: During lateral bending, the nucleus pulposus was pushed to the opposite side and the inferior cervical nerve roots of the opposite side were stretched. Cross-sectional diameter at the level of C6-7 during flexion was larger than that in lateral bending (P < .05). Comparing extension with flexion, we found that changes in all segments' areas were significant (P < .05). There was no significant difference in the sagittal diameter at any segment during all postures (P > .05). CONCLUSIONS: During lateral bending, the nucleus pulposus of neck were pushed into the opposite side, and inferior cervical nerve roots of the opposite side were stretched. The C5, C6, and C7 nerve roots appeared to undergo excessive stretch when an excessive lateral bending beyond the physiologic range was undergone. This study provides some additional evidence about the mechanics of cervical spine motion.

Sacral neuromodulation for the treatment of chronic functional anorectal pain: a single center experience.

INTRODUCTION: Treatment of functional anorectal pain disorders remains a challenge. The purpose of this study is to describe a single center experience with sacral neuromodulation for the treatment of chronic functional anorectal pain. METHODS: This is a retrospective study based on prospectively collected data of patients treated with sacral neuromodulation for functional anorectal pain from April 2005 to August 2008. Symptoms were analyzed using a visual analog scale pain score (0 to 10). A 7-point Likert scale was used to rate global perceived effect. All patients had a percutaneous nerve evaluation and subsequent test stimulation to assess sacral neuromodulation outcome prior to permanent implantation. Patients were eligible for permanent sacral neuromodulation in case of a pain score <3 during test stimulation and/or >50% decrease in the pain score compared to baseline. RESULTS: Nine patients (2 males) were included in this study. Mean age was 53.8 years (27.6 to 74.0). Four patients (1 male) had successful test stimulation and were eligible for permanent implantation. Median pain score decreased from 8.0 (6.0 to 9.0) to 1.0 (0 to 2.0). All patients experienced a lasting improvement during the follow-up till 24 months. Global perceived effect in successful patient was 1 (completely recovered) in one patient and 2 (much improved) in three patients. CONCLUSION: This study showed that sacral neuromodulation can be a successful treatment for functional anorectal pain not responding to other treatments. Improvement obtained during test stimulation is a good predictor (diagnostic) for sustained success of permanent sacral neuromodulation.

Electrode contact configuration and energy consumption in spinal cord stimulation.

OBJECTIVE: To test the hypothesis that in spinal cord stimulation, an increase in the number of cathodes increases the energy per pulse, contrary to an increase in the number of anodes, which decreases energy consumption per pulse. METHODS: Patients with an Itrel III (7425; Medtronic, Inc., Minneapolis, MN) implantable pulse generator and a Pisces-Quad (3487A; Medtronic, Inc.) implantable quadripolar lead were selected for this study. A set of 7 standard contact configurations was used for each patient. Resistor network models mimicking these configurations were constructed. The University of Twente's Spinal Cord Stimulation software was used to simulate the effect of these contact configurations on large spinal nerve fibers. To allow a comparison of the measured and modeled energy per pulse, all values were normalized. RESULTS: Both the empirical and the modeling results showed an increase in energy consumption with an increasing number of cathodes. Although the patient data with 1 and 2 cathodes did not differ significantly, energy consumption was significantly higher when 3 cathodes were used instead of 1 or 2 cathodes. The average energy consumption was significantly higher when bipolar stimulation was used instead of monopolar cathodal stimulation. An increasing number of anodes caused a decrease in energy consumption. CONCLUSION: When the paresthesia area can be covered with several configurations, it will be beneficial for the patient to program a configuration with 1 cathode and either no or multiple anodes.

The development of spinal cord anatomy.

A panel illustrating spinal cord injury in The Dying Lioness in the British Museum dates to 650 BC. This paper outlines the subsequent progression of knowledge of the anatomy of the spinal cord. The animal dissections of Galen are considered because his deductions persisted through the Dark Ages until the late 18th century. Anatomy advanced gradually to yield discoveries of the complex tracts and grey matter elements of the cord and their functions. Amongst many distinguished exponents, the works of Blasius, Huber, Vicq d'Azyr and Stilling are emphasised.

Posterior root-muscle reflexes elicited by transcutaneous stimulation of the human lumbosacral cord.

Continuous epidural stimulation of lumbar posterior root afferents can modify the activity of lumbar cord networks and motoneurons, resulting in suppression of spasticity or elicitation of locomotor-like movements in spinal cord-injured people. The aim of the present study was to demonstrate that posterior root afferents can also be depolarized by transcutaneous stimulation with moderate stimulus intensities. In healthy subjects, single stimuli applied through surface electrodes placed over the T11-T12 vertebrae with a mean intensity of 28.6 V elicited simultaneous, bilateral monosynaptic reflexes in quadriceps, hamstrings, tibialis anterior, and triceps surae by depolarization of lumbosacral posterior root fibers. The nature of these posterior root-muscle reflexes was demonstrated by the duration of the refractory period, and by modifying the responses with vibration and active and passive movements. Stimulation over the L4-L5 vertebrae selectively depolarized posterior root fibers or additionally activated anterior root fibers within the cauda equina depending on stimulus intensity. Transcutaneous posterior root stimulation with single pulses allows neurophysiological studies of state- and task-dependent modulations of monosynaptic reflexes at multiple segmental levels. Continuous transcutaneous posterior root stimulation represents a novel, non-invasive, neuromodulative approach for individuals with different neurological disorders.

Las lecciones derivadas del ASA Closed Claims Project (ASACCP). Proyecto de la ASA acerca de las razones que promovieron demandas contra anestesiólogos cuyos casos estuviesen ya archivados: 4a. parte. Anestesia Regional. Análisis de las demandas sobre casos/hechos asociados con la anestesia regional en la sala de operaciones / Lessons learned fron the ASA Closed Claims Project (ASACCP). Project about the reasons for which claims against anesthesiologists were renewed in cases that had already been closed: part. 4. Regional Anesthesia. Analysis of claims concerning regional anesthesia in the OR

Cuando se comparan las consecuencias de los accidentes anestésicos reclamados que constan en la base de datos del ASA CCP (Closed Claims Project), es significativo señalar que hubo un alto porcentaje de lesiones temporarias o no incapacitantes en los casos de anestesia regional (64 por ciento vs 46 por ciento p<0,05). Entre las lesiones incapacitantes permanentes derivadas de injurias del sistema nervioso periférico se hallan manifestaciones como la paraplejía y la cuadriplejía. Catorce de las reclamaciones legales asociadas con la paraplejía se debieron a síndromes de la anestesia espinal anterior. Los daños neurológicos permanentes fueron la causa más común de los daños incapacitantes, el más frecuente de los cuales (23 por ciento) fue asociado a bloqueos nerviosos para anestesia ocular (13 retrobulbares, 3 peribulbares) en los que hubo pérdida de la visión del ojo afectado. De todas maneras, se debe señalar que las complicaciones neurológicas como manifestaciones secundarias a la utilización de anestésicos locales para anestesia regional son muy poco frecuentes (0,02 y 0,07 por ciento de los casos), aunque es bastante común observar la aparición de manifestaciones neurológicas transitorias (entre 0,01 y 0,8 por ciento). La parestesia y el dolor durante la inyección son señales peligrosas ya que anuncian la posibilidad de la complicación. Se han descripto también abscesos peridurales y meningitis, en especial cuando se realizan bloqueos centrales con catéteres de pequeño diámetro a fin de alcanzar analgesia central para el dolor crónico. En la base de datos de la Mutual de Médicos Anestesiólogos de Buenos Aires están registradas las demandas realizadas contra anestesiólogos y los casos en los cuales los médicos, enfrentados a un incidente crítico, notifican la situación en previsión de una eventual demanda. Al igual que en el estudio de la ASACCP, desconocemos el número total de anestesia realizadas por los colegas adheridos. Hasta el 2004 hubo 339 notificaciones que incluyen 74 demandas, 24 causas penales y 50 causas civiles; 124 casos correspondieron a la anestesia regional, mientras que 215 formaron el grupo de pacientes que recibieron anestesia general. En 8 de los pacientes que presentaron radiculopatías se realizó una anestesia subaracnoidea con bupivacaína al 0,5 por ciento en solución hiperbara, habiéndose inyectado 15 mg (3 ml) de la solución anestésica...(AU)

Las lecciones derivadas del ASA Closed Claims Project (ASACCP). Proyecto de la ASA acerca de las razones que promovieron demandas contra anestesiólogos cuyos casos estuviesen ya archivados: 4a. parte. Anestesia Regional. Análisis de las demandas sobre casos/hechos asociados con la anestesia regional en la sala de operaciones / Lessons learned fron the ASA Closed Claims Project (ASACCP). Project about the reasons for which claims against anesthesiologists were renewed in cases that had already been closed: part. 4. Regional Anesthesia. Analysis of claims concerning regional anesthesia in the OR

Cuando se comparan las consecuencias de los accidentes anestésicos reclamados que constan en la base de datos del ASA CCP (Closed Claims Project), es significativo señalar que hubo un alto porcentaje de lesiones temporarias o no incapacitantes en los casos de anestesia regional (64 por ciento vs 46 por ciento p<0,05). Entre las lesiones incapacitantes permanentes derivadas de injurias del sistema nervioso periférico se hallan manifestaciones como la paraplejía y la cuadriplejía. Catorce de las reclamaciones legales asociadas con la paraplejía se debieron a síndromes de la anestesia espinal anterior. Los daños neurológicos permanentes fueron la causa más común de los daños incapacitantes, el más frecuente de los cuales (23 por ciento) fue asociado a bloqueos nerviosos para anestesia ocular (13 retrobulbares, 3 peribulbares) en los que hubo pérdida de la visión del ojo afectado. De todas maneras, se debe señalar que las complicaciones neurológicas como manifestaciones secundarias a la utilización de anestésicos locales para anestesia regional son muy poco frecuentes (0,02 y 0,07 por ciento de los casos), aunque es bastante común observar la aparición de manifestaciones neurológicas transitorias (entre 0,01 y 0,8 por ciento). La parestesia y el dolor durante la inyección son señales peligrosas ya que anuncian la posibilidad de la complicación. Se han descripto también abscesos peridurales y meningitis, en especial cuando se realizan bloqueos centrales con catéteres de pequeño diámetro a fin de alcanzar analgesia central para el dolor crónico. En la base de datos de la Mutual de Médicos Anestesiólogos de Buenos Aires están registradas las demandas realizadas contra anestesiólogos y los casos en los cuales los médicos, enfrentados a un incidente crítico, notifican la situación en previsión de una eventual demanda. Al igual que en el estudio de la ASACCP, desconocemos el número total de anestesia realizadas por los colegas adheridos. Hasta el 2004 hubo 339 notificaciones que incluyen 74 demandas, 24 causas penales y 50 causas civiles; 124 casos correspondieron a la anestesia regional, mientras que 215 formaron el grupo de pacientes que recibieron anestesia general. En 8 de los pacientes que presentaron radiculopatías se realizó una anestesia subaracnoidea con bupivacaína al 0,5 por ciento en solución hiperbara, habiéndose inyectado 15 mg (3 ml) de la solución anestésica...

Use of chronic sacral nerve stimulation in neurological voiding disorders.

AIM: Neurogenic low urinary tract dysfunctions unresponsive to medical and conservative therapy are difficult to manage. Nowadays they can be treated with Sacral Nerve Stimulation (SNS), even if clinical experiences reported in literature are still limited. METHODS: We performed SNS in 6 patients with neurogenic bladder: 3 patients had incontinence-urgency (1 myelitis, 1 multiple sclerosis, 1 autonomic polineuropathy) and 3 patients had urinary retention (1 incomplete spinal cord lesion, 1 operation for discal hernia T5-T6, 1 hysterectomy). RESULTS: Among cases with incontinence-urgency we achieved complete control of the bladder in 2 patients while in 1 patient the number of urinary losses was reduced of the 80%. In 2 patients with urinary retention we obtained complete recovery of the bladder function, while in 1 patient the number of cateterisms/die reduced of 50%, the urinary volume for micturion increased and residual urinary volume decreased. Results were unchanged during the follow-up (maximum 26 months), except for 1 patient in which a partial loss of effectiveness occurred. CONCLUSIONS: Chronic electric stimulation of S3 sacral roots via an implanted neuroprotesis is therefore an effectiveness, save and promising therapeutic option in treatment of neurogenic bladder dysfunctions.

Ascending spinal systems in the fish, Prionotus carolinus.

The fin rays of the pectoral fin of the sea robins (teleostei) are specialized chemosensory organs heavily invested with solitary chemoreceptor cells innervated only by spinal nerves. The rostral spinal cord of these animals is marked by accessory spinal lobes which are unique enlargements of the dorsal horn of the rostral spinal segments receiving input from the fin ray nerves. Horseradish peroxidase (HRP) and 1,1;-dioctadecyl-3,3,3', 3'-tetramethylindocarbocyanine perchlorate (diI) were used as anterograde and retrograde tracers to examine the connectivity of these accessory lobes and the associated ascending spinal systems in the sea robin, Prionotus carolinus. The majority of dorsal root fibers terminate within the accessory lobes at or nearby their level of entrance into the spinal cord. A few dorsal root axons turn rostrally in the dorsolateral fasciculus to terminate in the lateral funicular complex situated at the spinomedullary junction. The lateral funicular complex also receives a heavy projection from the ipsilateral accessory lobes. In addition, it contains a few large neurons that project back onto the accessory lobes. Injections of either diI or HRP into the lateral funicular complex label fibers of the medial lemniscus which crosses the midline in the caudal medulla to ascend along the ventral margin of the contralateral rhombencephalon. Within the medulla, fibers leave the medial lemniscus to terminate in the inferior olive and in the ventrolateral medullary reticular formation. Upon reaching the midbrain, the medial lemniscus turns dorsally to terminate heavily in a lateral division of the torus semicircularis, in the ventral optic tectum, and in the lateral subnucleus of the nuc. preglomerulosus of the thalamus. Lesser projections also reach the posterior periventricular portion of the posterior tubercle with a few fibers terminating along the ventral, posterior margin of the ventromedial (VM) nucleus of the thalamus. The restricted projection to the ventral tectum is noteworthy in that this part of the tectum maintains the representation of the ventral visual field, that is, the area in which the fin rays lie. A prominent spinocerebellar system is also evident. Both direct and indirect spinocerebellar fibers can be followed through the dorsolateral fasciculus, with or without relay in the lateral funicular nucleus and terminating in a restricted portion of the granule cell layer of the ipsilateral corpus cerebelli. The similarities in connectivity of the spinal cord between the sea robins and other vertebrates are striking. It is especially notable because sea robins utilize the chemosensory input from the fin rays to localize food in the environment. Thus, although these fish use their spinal chemosense as other fishes use their external taste systems, the spinal chemosense apparently relies on the medial lemniscal system to guide this chemically driven feeding behavior.

The impact of sacral root anatomy on selective electrical stimulation for bladder evacuation.

Although different structures have been studied with electrostimulation to elicit bladder evacuation, only the sacral root remains feasible for clinical application at present. However, the resultant concomitant contractions of the bladder and sphincteric muscles have been the principal problem over the last few decades. Attempts to identify fibers within the sacral ventral root that innervate the detrusor predominantly have been made by microsurgery alone or in combination with advanced electrical blocking techniques. This article evaluates our past and present efforts to achieve voiding in light of the mixed nature of sacral root anatomy.

Parameters in electrode positioning in thoracic percutaneous facet denervation: an anatomical study.

The purpose of the present study was to verify if needle placement in thoracic percutaneous facet denervation (PFD), based on bony landmarks, and under fluoroscopic guidance, would lead to constant anatomical positioning; and hence to an adequate placement at the assumed target, i.e., the medial branch of the dorsal ramus of the spinal nerve; and furthermore to determine if interpretation of the needle position by CT is more reliable than by fluoroscopy. The procedures were carried out bilaterally at all 12 levels on two cadavers, simulating the clinical setting as much as possible. In 44 cases the position of the needles was determined on hard copies of fluoroscopic images, 1.5 mm interval CT-images, surface-photographs, and on counterstained 25 microns sections obtained by a multirange heavy duty cryomicrotome. The sections established that standardized use of bony landmarks under fluoroscopic control can result in reproducible anatomical needle positioning in thoracic PFD. Nervous tissue was hit in 27 (61%) cases, but the supposed target structure, i.e., the medial branch "stem" was never hit. In none of the procedures was an accidental pleural puncture observed. The correlation between fluoroscopic images and sections was poor. The correlation between CT and sections was better, except for the mediolateral direction. The results of the present study suggest that "pure" anatomical positioning based on bony landmarks analogous to those used in the lumbar region is not reliable enough for thoracic PFD, and that corrections after electrostimulation substantially contribute to obtaining an adequate position of the needle.

A histological investigation of human lower lumbar intervertebral canal (foramen) dimensions.

OBJECTIVE: To determine the proximity of neural structures to the boundaries of the interpedicular zone of the intervertebral canal in cadaveric adult human spines at the L4-5 and L5-S1 spinal levels. DESIGN: Nine randomly chosen blocks of human lumbosacral spinal tissues were processed for histological examination and mensuration of their left and right L4-5 and L5-S1 interpedicular zones of the intervertebral canals (foramina). Measurements of the important interpedicular zone were made using a computerized morphometry system to determine (i) the ratio between the cross-sectional area of the interpedicular zone canal and its large neural structure(s), (ii) the proximity of these neural structures to the boundary of the interpedicular zone, and (iii) the horizontal length of the interpedicular zone of the intervertebral canal. RESULTS: The mean cross-sectional area ratio of the interpedicular zone of the intervertebral canal to large neural structure(s) is 22.9 (SD 6.7)-30.8 (SD 4.4)% at the L4-5 level and 24.9 (SD 5.3)-31.1 (SD 5.3)% at L5-S1. The cross-sectional area of the interpedicular zone is 3.3 (SD 0.5)-4.8 (SD 1.7) times (X) larger than that of the large neural structures at the L4-5 level, and 3.3 (SD 0.6)-4.2 (SD 0.8) at the L5-S1 level. The mean minimum distance between the large neural structure(s) and the boundary of the interpedicular zone ranges from 0.4 (SD 0.4)-0.8 (SD 0.9) mm at the L4-5 level and from 0.4 (SD 0.4)-0.6 (SD 0.3) mm at the L5-S1 level. The horizontal length of the interpedicular zone of the intervertebral canal ranges from 8.2-12.2 mm. CONCLUSION: Within the interpedicular zone of the intervertebral canal, the minimum distance between neural structures and the boundary can be as little as 0.4 (SD 0.4) mm. The possible ramifications of this finding are discussed with regard to a previous gross anatomical study performed by Crelin (1973) that emphasized the anatomically and clinically less relevant lateral border of the intervertebral canal.

The effects of compression on the physiology of nerve roots.

The spinal roots connect the central and peripheral nervous systems. In doing so, the nerve roots pass through the spinal column, where they are located in narrow spaces, close to vertebrae and intervertebral discs. At these locations, nerve roots can be subjected to mechanical compression in association with, for example, disc herniation, spinal stenosis and spine trauma. In this article, basic aspects of the anatomy and physiology of nerve roots are reviewed. Nerve fiber arrangements, connective tissue layers and blood supply are described. The effects of compression on nerve root structure and function are summarized, based on experimental studies involving analyses of nerve function, nutrition, including blood flow, and edema formation in the nerve root. Pain mechanisms in nerve root compression are reviewed in relation to various clinical conditions.

Pain: its physiology and rationale for management. Part I. Neuroanatomical substrate of pain.

Pain, one of man's most worrisome afflictions, is also one of neurobiology's most challenging problems. Even its definition is beset with controversy. The origin and current resolution of this controversy are presented in this paper, but the major purpose of Part I is to review the anatomical substrate of the peripheral and central nervous systems involved in pain. Structural and functional characteristics of pain receptors and their afferent fibers are described, with emphasis upon current hypotheses regarding putative neural transmitters and possible mechanisms for signal transduction. Hitherto unrecognized details of the cytoarchitecture, anatomical organization, and circuitry of the dorsal horns are reviewed. The paper concludes with a consideration of the major components of the ascending and descending systems of subserving pain.