Relationship of the Exiting Nerve Root and Superior Articular Process in Kambin's Triangle: Assessment of Lumbar Anatomy Using Cadavers and Computed Tomography Imaging.

BACKGROUND: Percutaneous transforaminal endoscopic diskectomy has been a major treatment for lumbar disk herniation. However, damage to exiting nerve roots is one of the most severe complications in this surgery. In this paper, the relationship of the exiting nerve root and the superior articular process in Kambin's triangle of the lumbar intervertebral foramen was assessed using cadavers and computed tomography (CT) imaging. METHODS: The anatomic relationship between the exiting nerve root and the superior articular process in Kambin's triangle of the intervertebral foramen was investigated on 6 cadavers. The distance between the exiting nerve and the superior articular process of the L1-2 to L5-S1 intervertebral foramina was measured using multiplane reconstruction. RESULTS: The bone-nerve space between the exiting nerve root and the superior articular process in Kambin's triangle was quite narrow both in cadaver and CT imaging study. The distance of the L5-S1 intervertebral foramen was the greatest, which was no more than 5.77 ± 0.56 mm. The distances increased gradually from the tip to the root, and the distances between the root and the tip were 0.91 ± 0.31 to 1.86 ± 0.57 mm, which took on a trapezoid shape that was relatively narrow at the proximal end and wider at the distal end. CONCLUSIONS: The bone-nerve space between the exiting nerve root and the superior articular process in Kambin's triangle of the lumbar intervertebral foramen was exceedingly narrow. It is necessary to perform a foraminoplasty to enlarge the working space and decrease the possibility of injury to the exiting nerve root.

Consecutive assessment of FA and ADC values of normal lumbar nerve roots from the junction of the dura mater.

BACKGROUND: Diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) are widely used in the evaluation of the central nervous system and recently have been reported as a potential tool for diagnosis of the peripheral nerve or the lumbar nerve entrapment. The purpose of this study was to evaluate consecutive changes in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of normal lumbar nerve roots from the junction of the dura mater. METHODS: The lumbar spinal nerves were examined in 6 male healthy volunteers (mean age, 35 years) with no experiences of sciatica, with a 3.0-T MR unit using a five-element phased-array surface coil. DTI was performed with the following imaging parameters: 11084.6/73.7 ms for TR/TE; b-value, 800 s/mm2; MPG, 33 directions; slice thickness, 1.5 mm; and total scan time, 7 min 35 s. ADC and FA values at all consecutive points along the L4, L5 and S1 nerves were quantified on every 1.5 mm slice from the junction of the dura mater using short fiber tracking. RESULTS: ADC values of all L4, 5, and S1 nerve roots decreased linearly up to 15 mm from the dura junction and was constant distally afterward. ADC values in the proximal portion demonstrated S1 > L5 > L4 (p < 0.05). On the other hand, FA values increased linearly up to 15 mm from the dura junction, and was constant distally afterward. FA values in the proximal portion showed L4 > L5 > S1 (p < 0.05). CONCLUSION: Our study demonstrated that ADC and FA values of each L4, 5, and S1 at the proximal portion from the junction of the dura matter changed linearly. It would be useful to know the normal profile of DTI values by location of each nerve root so that we can detect subtle abnormalities in each nerve root.

Assessment of reduced field of view in diffusion tensor imaging of the lumbar nerve roots at 3 T.

OBJECTIVES: To assess the value of reduced field of view (rFOV) imaging in diffusion tensor imaging (DTI) and tractography of the lumbar nerve roots at 3 T from the perspective of future clinical trials. METHODS: DTI images of the lumbar nerves were obtained in eight healthy volunteers, with and without the rFOV technique. Non-coplanar excitation and refocusing pulses associated with outer volume suppression (OVS) were used to achieve rFOV imaging. Tractography was performed. A visual evaluation of image quality was made by two observers, both senior musculoskeletal radiologists. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in L5 and S1 roots. RESULTS: rFOV images of the L5 and S1 roots were assessed as being superior to full FOV (fFOV) images. Image quality was rated as good to excellent by both observers. Interobserver agreement was good. No significant difference was found in FA and ADC measurements of the L5 or S1 roots. On the contrary, only poor-quality images could be obtained with fFOV imaging as major artefacts were present. CONCLUSION: The rFOV approach was essential to achieve high-quality DTI imaging of lumbar nerve roots on 3-T MRI. KEY POINTS: • Diffusion tensor 3-T MR imaging of lumbar nerve roots creates severe artefacts. • A reduced field of view drastically reduces artefacts, thereby improving image quality. • Good-quality tractography images can even be obtained with rFOV imaging. • rFOV DTI is better than fFOV DTI for clinical studies.

Long thoracic nerve: anatomy and functional assessment.

BACKGROUND: The anatomy and function of the long thoracic nerve are not fully understood. The purposes of this study were to clarify the anatomy of the long thoracic nerve and to propose a clinical test to assess the function of the upper division of the long thoracic nerve. METHODS: The long thoracic nerve and the serratus anterior muscle were studied in fifteen fresh cadavera. Six patients had an operation to treat a brachial plexus injury, and the long thoracic nerve was electrically stimulated. The resulting shoulder motion was then observed. RESULTS: The long thoracic nerve was formed by branches arising from the C5, C6, and C7 nerve roots. The C5 and C6 branches joined beneath the scalenus medius muscle to form the upper division of the long thoracic nerve, which was located 1 cm posteriorly and superiorly to the upper trunk origin. The union of the upper division with the branch from C7 occurred caudally, in the axillary region. Two branches from the upper division of the long thoracic nerve to the upper portion of the serratus anterior muscle were consistently identified. After electrical stimulation of the upper division branches, shoulder protraction was observed. CONCLUSIONS AND CLINICAL RELEVANCE: In the supraclavicular region, the long thoracic nerve has a trajectory parallel to the brachial plexus, which is contrary to the schematic representation in most textbooks. The upper division of the long thoracic nerve can be assessed by the shoulder protraction test.

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...