Inyección subdural: complicación en la técnica peridural lumbar: revisión bibliográfica / Subdural injection: complication in lumbar epidural block: review of the literature

Se realiza una revisión bibliográfica sobre inyección subdural en la técnica peridural lumbar. se analizan los aspectos anatómicos, se describen las diferentes formas de presentación y su imagen radiológica, se discuten los criterios diagnósticos, los posibles efectos de la inyección en dicho espacio y la conducta a tomar, una vez detectada la complicación.

A bibliographic review about lumbar epidural subdural injection is done. the anatomic aspects, the different forms of presentation, and the radiological image are described. the diagnostic criteria, the effects of injection in this space and the management of the complication are discussed.

Various patterns of the middle cerebral vein and preservation of venous drainage during the anterior transpetrosal approach.

OBJECTIVE: The drainage of the superficial middle cerebral vein (SMCV) has previously been classified into 4 subtypes. Extradural procedures and dural incisions during the anterior transpetrosal approach (ATPA) may interrupt the route of drainage from the SMCV. In this study, the authors examined the relationship between anatomical variations in the SMCV and the corresponding surgical modifications to the ATPA that are necessary for venous preservation. METHODS: This study included 48 patients treated via the ATPA in whom the SMCV was examined using 3D CT venography. The drainage patterns of the SMCV were classified into 3 types: cavernous or absent (Type 1), sphenobasal (Type 2), and sphenopetrosal (Type 3). Type 2 was subdivided into medial (Type 2a) and lateral (Type 2b), and Type 3 was subdivided into vein (Type 3a), vein and sinus (Type 3b), and sinus (Type 3c). The authors performed 3 ATPA modifications to preserve the SMCV: epidural anterior petrosectomy with subdural visualization of the sphenobasal vein (SBV), modification of the dural incision, and subdural anterior petrosectomy. Standard ATPA can be performed with Type 1, Type 2a, and Type 3a drainage. With Type 2b drainage, an epidural anterior petrosectomy with subdural SBV visualization is appropriate. The dural incision should be modified in Type 3b. With Type 3c, a subdural anterior petrosectomy is required. RESULTS: The frequency of each type was 68.7% (33/48) in Type 1, 8.3% (4/48) in Type 2a, 4.2% (2/48) in Type 2b, 14.6% (7/48) in Type 3a, 2.1% (1/48) in Type 3b, and 2.1% (1/48) in Type 3c. No venous complications were found. CONCLUSIONS: The authors propose an SMCV modified classification based on ATPA modifications required for venous preservation.

Subarachnoid, subdural and interdural spaces at the clival region: an anatomical study.

AIM: We aimed to show the significance of the anterior pontine membrane as a determining structure between the subdural and subarachnoid space in the clival region. MATERIAL AND METHODS: Five adult cadaver heads and five cerebral hemispheres were used. The skull vault and hemipheres were removed by sectioning through the pontomesencephalic junction. Five other heads hemispheres were removed but the arachnoid membrane was protected and the cerebral side of the clival dura mater was dissected. In another specimen, the dural porus of the abducens nerve was sectioned for histological evaluation. Three cases of hematoma at the clivus were presented to support our findings. RESULTS: The anterior pontine membrane is the arachnoid membrane forming the anterior wall of the prepontine cistern with its lateral extension at the skull base. This membrane forms the subdural and subarachnoid spaces by forming a barrier between the clival dura mater and neurovascular structures of the brainstem. There were rigid fibrous trabeculations between both cerebral and periosteal dural layers forming the basilar plexus as the interdural space in the clivus. CONCLUSION: The anterior pontine membrane separates the subdural and subarachnoid spaces at the clival region. The hematomas of the clival region require to be evaluated with consideration given to the existance of the subdural space.

Anatomic study of the anterior skull base via an endoscopic transnasal approach.

OBJECTIVES: With rapid advances in endoscopic neurosurgery, it has become possible to treat some lesions located in the anterior skull base through a transnasal approach. This anatomic study was undertaken to describe the area of surgical exposure of the anterior skull base afforded by transnasal approaches with an endoscope, as well as to provide references for clinical practice. METHODS: Thirty bony skull base specimens (all Chinese) were used, and 10 injected adult cadaver heads (all Chinese) were dissected for a simulated endoscopic transnasal approach to the anterior skull base. The distance between the bilateral optic canals was measured in skull base specimens and the distance between the columella and anterior ethmoid artery or posterior ethmoid artery was measured on both sides in adult cadaver heads. RESULTS: The optic canals were 15.13±1.69 mm apart. The distance between the columella and posterior ethmoid artery was 71.01±3.99 mm on the left side and 72.27±3.97 mm on the right side. The distance between the columella and anterior ethmoid artery was 64.811±3.74 mm on the left side and 64.18±3.74 mm on the right side. The endoscopic transnasal approach to the anterior skull base exposed the optic protuberance, sellar floor, crista galli, anterior ethmoid artery, and posterior ethmoid artery. In addition, bilateral olfactory bulbs, olfactory tracts, and optic nerves beneath the dura mater were also revealed. CONCLUSIONS: The anatomic data as well as established anatomic landmarks associated with endoscopic surgery would benefit clinical practice.

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The subdural space of the spine: A lymphatic sink? Myodil's last message.

Following the radiological study of a large number of myelograms, starting over 50 years ago when the only clinical contrast medium available to show the contents of the spinal canal was an iodized oil, the author has collected a number of examples where the oil was inadvertently injected into the subdural area, rather than the intended subarachnoid space. By taking follow-up films at various intervals following the inadvertent injection, it has been possible to study the extent to which the subdural space could become visualized from a lumbar injection, the contrast medium sometimes passing to the top of the cervical region and the lower part of the sacrum. Also, the contrast passed outward along the peri-neural lymphatic sheaths or spaces of the issuing spinal nerves, where it might remain for months, and under the influence of gravity it could extend for a considerable way. It also passed into abdominal and thoracic lymph vessels and nodes. Considering the morphology, predictability, and ease with which the demonstrated subdural space fills, the author concludes that the subdural region is a true and functionally significant "space," and an important conduit or functional part of the body's lymphatic system. He also considers that it has implications for the spread or dissemination of various organisms, substances or pathological conditions, as well as being part of the normal conduit for reabsorption of CSF with implications for hydrocephalus, and with potential for misplacement of spinal anaesthetic agents.

Subdural block and the anaesthetist.

There are a number of case reports describing accidental subdural block during the performance of subarachnoid or epidural anaesthesia. However it appears that subdural drug deposition remains a poorly understood complication of neuraxial anaesthesia. The clinical presentation may often be attributed to other causes. Subdural injection of local anaesthetic can present as high sensory block, sometimes even involving the cranial nerves due to extension of the subdural space into the cranium. The block is disproportionate to the amount of drug injected, often with sparing of sympathetic and motor fibres. On the other hand, the subdural deposition can also lead to failure of the intended block. The variable presentation can be explained by the anatomy of this space. High suspicion in the presence of predisposing factors and early detection could prevent further complications. This review aims at increasing awareness amongst anaesthetists about inadvertent subdural block. It reviews the relevant anatomy, incidence, predisposing factors, presentation, diagnosis and management of unintentional subdural block during the performance of neuraxial anaesthesia.

The intradural space: the fourth place to go astray during epidural block.

BACKGROUND: Considerable uncertainty exists regarding accidental injection of local anaesthetic into the 'subdural space' during attempted epidural block. A whole range of clinical findings, from excessively high to failed blocks has been reported although many of these findings appear difficult to explain on the basis of our current knowledge of the anatomy. The existence of another, adjacent space, the intradural space, is postulated. METHODS: Our study of atypical epidural blocks using contrast injection and radiographic screening has now obtained data on 130 patients, and results were reviewed retrospectively, searching for contrast flowing into the subdural region. RESULTS: Radiographic studies have revealed 10 patients with an unusual dense localised collection of contrast in a space previously unrecognised by anaesthetists. Clinical presentation was of inadequate neuraxial block, which could eventually be corrected by top-up doses, but with the possible risk of developing a high block. Late radiographic pictures revealed contrast escaping from the mass into the epidural, subdural or subarachnoid spaces. CONCLUSIONS: A review of electron microscopy studies suggested that a 'secondary' subdural space could be opened up by trauma in the distal layers of the dura. Our findings suggest that injection into this 'intradural' space can occur, resulting in an initially inadequate neuraxial block with limited spread. Further volumes of local anaesthetic can be expected to produce satisfactory block, probably as a result of escape to the epidural space. However, late spread to the subdural or subarachnoid space may occur.

Surgical management of giant trigeminal schwannomas extending into the parapharyngeal space.

PURPOSE: Trigeminal schwannomas extending into the deep parapharyngeal space are relatively rare, and a surgical approach to such tumors has not been well established. We report four cases in which the tumors were completely removed by using a combination of three approaches. METHODS: Four patients with trigeminal schwannomas extending into the extracranial space were surgically treated using a combination of the transcervical approach, anterolateral retromaxillar pathway via gingivobuccal sulcus, and epi and interdural middle fossa approach. RESULTS: The maximum diameters of the tumors ranged from 4 to 7 cm. Three tumors extended beyond the lower end of the maxillary sinus. All tumors were completely excised. The Karnofsky performance scales after surgery were more than 90% in all patients. CONCLUSION: Although the tumors extending to the deep parapharyngeal space are difficult to completely remove via a single approach, a combined approach is useful in these huge extracranial extensions.

Anatomy and development of the meninges: implications for subdural collections and CSF circulation.

The dura is traditionally viewed as a supportive fibrous covering of the brain containing the dural venous sinuses but otherwise devoid of vessels and lacking any specific function. However, review of the embryology and anatomy reveals the dura to be a complex, vascularized and innervated structure, not a simple fibrous covering. The dura contains an inner vascular plexus that is larger in the infant than in the adult, and this plexus likely plays a role in CSF absorption. This role could be particularly important in the infant whose arachnoid granulations are not completely developed. Although subdural hemorrhage is frequently traumatic, there are nontraumatic conditions associated with subdural hemorrhage, and the inner dural plexus is a likely source of bleeding in these nontraumatic circumstances. This review outlines the development and age-specific vascularity of the dura and offers an alternative perspective on the role of the dura in homeostasis of the central nervous system.

A simple technique for bridging small cranial dural defects without the use of grafts: technical note.

A watertight closure of the dura is important in preventing post-operative complications. Various techniques are described to close small dura defects. We present a simple technique that uses on site homologues dura tissue to bridge small dura defects by separating the periosteum from the inner meningeal layer. This provides a low-cost, tension-free repair without the use of synthetic materials or need to harvest autologous materials.

Tailored resections in occipital lobe epilepsy surgery guided by monitoring with subdural electrodes: characteristics and outcome.

PURPOSE: Occipital lobe epilepsy is uncommon in epilepsy surgery series and often difficult to assess due to rapid seizure propagation, misleading seizure semiology and confounding interictal epileptiform activity. Ictal recordings with surface electrodes may not define properly the seizure onset zone in surgical evaluation for intractable occipital epilepsy. Specially in dysplastic lesions, the extension of the epileptogenic zone is not well defined by neuroimaging techniques, therefore, implantation of intracranial electrodes is often indicated. In this study we present our experience with individually tailored resections of occipital lobe epileptic foci guided by monitoring with subdural electrodes. METHODS: Data from interictal and ictal surface and intracranial recordings, neuroimaging, surgical treatment, pathology and outcome of seven patients are presented. RESULTS: The most common seizure type (6/7 patients) was complex partial with temporal lobe semiology, five patients experienced visual auras as part of their complex partial seizures or as separate simple partial seizures. Two patients had seizures suggesting supplementary motor area involvement. One patient had temporal as well as frontal seizure propagation. Neuroimaging showed lesions in 6/7 patients. Pathological studies revealed cortical dysplasia and tumors as the most common causes. Intracranial recordings (6/7 patients) revealed focal onset in 2 patients, regional onset in 2, and diffuse onset in 2. Surgery was performed according to intracranial recordings restricting resections in cases with focal seizure onset (even in large dysplastic lesions) and performing wider resections in patients with regional or diffuse onset. Five of seven patients are seizure free after 12-55 months (mean 24.3). The two remaining patients may be classified as Engel 2b and 3a. CONCLUSIONS: This series of occipital lobe epilepsy surgery shows that, even in patients with cortical dysplasias, restricted resections may have a good outcome and that intracranial monitoring is usually necessary in order to design an individually tailored resection.

El saco dural humano. Morfología de la dura-aracnoides espinal. Origen del espacio subdural espinal / The human dural sac. Morphology of the spinal dura-arachnoid membrane. Origin of the spinal subdural space

Esta revisión resume los hallazgos encontrados en el saco dural de cadáveres de recién fallecidos estudiados con diferentes técnicas histológicas. El saco dural espinal está formado por tres estructuras concéntricas: la duramadre, que ocupa el 85-90 por ciento de su espesor, del lado externo; el compartimiento subdural, integrado por células neuroteliales, y la lámina aracnoidea, que ocupa el 5 al 8 por ciento interno. La duramadre, que consta de aproximadamente 80 láminas durales concéntricas, es una estructura permeable y fibrosa, por lo cual posee resistencia mecánica. El compartimiento subdural es una estructura concéntrica, celular, de resistencia mecánica muy baja, donde se pueden producir fisuras concéntricas por rotura de las células neuroteliales dando origen a un espacio subdural adquirido. La lámina aracnoidea es una estructura celular con mayor resistencia mecánica que el compartimiento subdural. Sus células están firmemente unidas por uniones especializadas de membrana y forman una barrera semipermeable que regula el pasaje de sustancias a través del espesor del saco dural.

El saco dural humano. Morfología de la dura-aracnoides espinal. Origen del espacio subdural espinal / The human dural sac. Morphology of the spinal dura-arachnoid membrane. Origin of the spinal subdural space

Esta revisión resume los hallazgos encontrados en el saco dural de cadáveres de recién fallecidos estudiados con diferentes técnicas histológicas. El saco dural espinal está formado por tres estructuras concéntricas: la duramadre, que ocupa el 85-90 por ciento de su espesor, del lado externo; el compartimiento subdural, integrado por células neuroteliales, y la lámina aracnoidea, que ocupa el 5 al 8 por ciento interno. La duramadre, que consta de aproximadamente 80 láminas durales concéntricas, es una estructura permeable y fibrosa, por lo cual posee resistencia mecánica. El compartimiento subdural es una estructura concéntrica, celular, de resistencia mecánica muy baja, donde se pueden producir fisuras concéntricas por rotura de las células neuroteliales dando origen a un espacio subdural adquirido. La lámina aracnoidea es una estructura celular con mayor resistencia mecánica que el compartimiento subdural. Sus células están firmemente unidas por uniones especializadas de membrana y forman una barrera semipermeable que regula el pasaje de sustancias a través del espesor del saco dural. (AU)

Unintended subdural injection: a complication of epidural anesthesia--a case report.

Epidural anesthesia is practiced in virtually every clinical setting. Its safety and versatility have supported increasing use for more and varied therapies. In a healthy patient in whom near-complete left hemiparesis developed following a routine continuous epidural anesthetic for labor, subdural deposit of the local anesthetic was suspected. The following case and discussion may help illustrate the mechanism behind this complication and how it can be detected, treated, and, possibly, avoided.

Alleviation of intracranial air using carbon dioxide gas during intraventricular tumor resection.

OBJECTIVES/PURPOSES: Postoperative vomiting occurs more frequently in patients after intraventricular surgery than after other intracranial surgeries. This has been attributed to intracranial air. Carbon dioxide gas (CO2) has properties beneficial to the treatment of some medical disorders, displaying a higher specific gravity and more rapid absorption into surrounding tissues than air. We therefore, attempted to replace air with CO2 during intra- and paraventricular tumor resections. The aim of the present study was to elucidate whether intracranial air after intraventricular surgery could be alleviated safely using CO2, and investigate its clinical usefulness. PATIENTS AND METHODS: CO2 was introduced into the subdural space at 2l/min through a silicon tube from time of dural incision to closure. Subjects comprised 40 patients alternately assigned to one of two groups: the trial group (n=20) receiving CO2 treatment; and controls (n=20) without CO2 treatment. RESULTS: Intra- and postoperatively, no patients showed complications caused by CO2 treatment. Postoperatively, intraventricular gas shown on CT scans disappeared significantly sooner in the trial group than in controls. Frequency of postoperative vomiting was significantly lower in the trial group than in controls. CONCLUSION: Intracranial air after intraventricular surgery can be safety alleviated using CO2.

Low frequency electrical stimulation through subdural electrodes in a case of refractory status epilepticus.

OBJECTIVE: We delivered low frequency stimulation through subdural electrodes to suppress seizures in a case of refractory status epilepticus (RSE). METHODS: A 26-year-old female developed RSE after several days of febrile illness. Seizure control required continuous infusion of two anesthetics plus high doses of 2-4 enteral antiepileptic drugs. After 3 months of RSE, subdural strips were placed to determine surgical candidacy. Five independent ictal onset zones were identified. Because she was a poor candidate for epilepsy surgery and had a poor prognosis, the implanted subdural electrodes were used to administer 0.5 Hz stimulations to the ictal onset zones in 30 min trains daily for 7 consecutive days in an attempt to suppress seizures. RESULTS: After 1 day of stimulation, one anesthetic agent was successfully discontinued. Seizures only returned by the 4th day when the second anesthetic had been reduced by 60%. Upon returning, seizures arose from only one of the 5 original ictal onset zones. Unfortunately, RSE persisted, and she eventually died. CONCLUSIONS: In this case of RSE, low frequency stimulation through subdural electrodes transiently suppressed seizures from all but one ictal onset zone and allowed significant reduction in seizure medication. SIGNIFICANCE: Low frequency cortical stimulation may be useful in suppressing seizures.

Subdural placement of an epidural catheter detected by nerve stimulation.

PURPOSE: Subdural placement of an epidural catheter is rare and difficult to detect. Electrical stimulation of the epidural space can be useful to detect such an event. The purpose of the present case report is to confirm the efficacy of electrical stimulation to detect a subdural placement of an epidural catheter and to illustrate this unusual positioning by computed tomography (CT) scan images. CLINICAL FEATURES: A 51-yr-old man was scheduled for an aorto-iliac bypass on a combined epidural and general anesthesia technique. Electrical epidural stimulation was used. A very low threshold of 0.3 mA was observed with diffuse response movement at T3 and at T10, without cerebrospinal fluid return on catheter aspiration. An injection of 12 mL of 2% lidocaine with epinephrine 1/200,000 produced signs of iv injection of local anesthetic and an extensive block. Subdural placement of the catheter, suspected by the low current threshold response to epidural catheter stimulation, was confirmed by CT scan imaging. CONCLUSION: The present case report confirms that electrical stimulation of the epidural space is useful to detect misplacement of epidural catheter such as a subdural placement. CT scan imaging of subdural positioning of an epidural catheter is presented.