Dural Sleeve Research Articles

The effect of using synthetic vs. biological dural substitutes during prenatal and postnatal repair of spina bifida on spinal cord tethering-a review of literature.

Spina bifida is a congenital neural tube closure defect, with myelomeningocele being the most clinically significant open neural tube defect occurring in one in 1000 births worldwide as reported by Phillips LA et al. (Curr Probl Pediatr Adolesc Health Care 47(7):173-177, 2017) and Zerah M and Kulkarni AV (Handb Clin Neurol 112:975-991, 2013). With advances in fetal surgery, this condition can be corrected in utero. Despite such precision surgery, many complications may still arise, with consequent spinal cord tethering being a major one. When the roots of the spinal cord adhere to the spinal canal instead of floating freely within the dural sleeve within the canal, it is termed as "tethering" as discussed by Martínez-Lage JF et al. (Neurocirugia (Astur) 18(4):312-319, 2007). Tethering has a variety of complications, which are best avoided by analyzing the outcomes of the different dural substitutes and improving surgical techniques. This literature review evaluates the use of different dural substitutes in fetal and postnatal surgery, with their effects on spinal cord tethering. Finding a significant difference in spinal cord adherence outcomes between these two groups can help one introspect on the impact of ideal surgical techniques to be implemented, thus reducing subsequent tethering and other future surgical interventions.

Three-Dimensional Anatomy of the Hypoglossal Canal: A Plastinated Histologic Study

To provide a precise description of the morphology and morphometry of the hypoglossal canal (HC) and its relationship with surrounding structures by using the epoxy sheet plastination technique. Thirty human cadaveric heads were plastinated into 5 sets of gross transparent plastination slices and 43 sets of ultrathin plastination sections. The HC were examined at both macro- and micro levels in these plastination sections and the reconstructed 3-dimensional visualization model. The HC was an upward arched bony canal with a dumbbell-shaped lumen. According to the arched trajectory of its bottom wall, the HC could be divided into a medial ascending segment and a lateral descending segment. The thickness of the compact bone in the middle part of the HC was thinner than that at the intracranial and extracranial orifices. In 14 of 43 sides (32.6%), the posterior wall or the roof of the HC were disturbed by passing venous channels which communicated the posterior condylar emissary vein and the inferior petroclival vein. The trajectory of hypoglossal nerve in HC is mainly from anterosuperior to posteroinferior. The meningeal dura and the arachnoid extended into the HC along the hypoglossal nerve to form the dural and arachnoid sleeves and then fused with the nerve near the extracranial orifice of the HC. Knowledge of the detailed anatomy of the HC can be helpful in avoiding surgical complications when performing surgery for lesions and the occipital condylar screw placement in this complex area.

Microanatomical study of arachnoid granulations and meningeal architecture around Meckel’s cave

Although the microanatomy of Meckel’s cave (MC) has been well studied, there are still controversies regarding the meningeal architecture of the space. Moreover, there are only general mentions of the arachnoid granulations near MC in just a few sources. This study is aimed at determining the frequency, location, and anatomical variability of the main clusters of arachnoid granulations around MC. The dissection involved 26 isolated specimens of MC fixed in formalin (neutral buffered, 10%). This number included five freshly harvested specimens examined histologically. Additional paraffin block with MC horizontal section was taken from our neuroanatomical collection. Carefully selected anatomical and histological techniques were applied to assess the complex relationships between the arachnoid granulations and adjacent structures. Arachnoid granulations were found around MC in all specimens with different anatomical variations. The main clusters of arachnoid granulations were close to the trigeminal ganglion and its divisions. The dorsolateral wall of MC was a thick layer formed by interweaving bundles of collagen fibers arranged in various directions. The entire MC was surrounded by a dural sleeve (envelope). This sleeve separated MC from the lateral sellar compartment. At its anterior (rostral) end, it formed a cribriform area pierced by individual fascicles of the trigeminal nerve’s primary divisions. The connective tissue forming the sleeve was not only continuous with the epineurium but also shifted to the perineuria surrounding individual nerve fascicles. The meningeal architecture around MC has a complex and multilayer arrangement with a collagenous sleeve closely related to the trigeminal ganglion. Arachnoid granulations are typically found around MC.

Recognition of the variant type of spinal dural arteriovenous fistula: a rare but important consideration.

Spinal dural arteriovenous fistulas (SDAVFs) typically represent abnormal shunts between a radiculomeningeal artery and radicular vein, with the point of fistulization classically directly underneath the pedicle of the vertebral body, at the dural sleeve of the nerve root. However, SDAVFs can also develop in atypical locations or have more than one arterial feeder, which is a variant of SDAVF. The aim of this study was to describe the incidence and multidisciplinary treatment of variant SDAVFs in a single-center case series. Following institutional review board approval, the authors retrospectively analyzed their prospectively maintained database of patients with SDAVFs who presented between 2008 and 2020. For all patients, spinal digital subtraction angiograms were reviewed and variant SDAVFs were identified. Variant types of SDAVFs were defined as cases in which the fistulous point was not located underneath the pedicle. Patient demographics, angiographic features, clinical outcomes, and treatment modalities were assessed. Of 59 patients with SDAVFs treated at the authors' institution, 4 patients (6.8%) were identified as having a variant location of the shunt zone, pinpointed on the dura mater at the intervertebral level, further posteriorly within the spinal canal. In 3 cases (75%), a so-called bimetameric arterial supply was demonstrated. Recognition of the variant type of SDAVF is crucial for management, as correct localization of the fistulous point and bimetameric supply are critical for successful surgical disconnection, preventing delay in achieving definitive treatment.

"On Arrival Block"-Management of Upper Extremity Trauma with Resuscitation in the Operating Room.

"On Arrival Block," wherein a brachial block is given to a severely injured upper extremity as the first step of the management protocol in the main operating room, bypassing the emergency department, has been found to be a "game changer" in trauma care. Immediate pain relief on arrival builds confidence in the system, allows pain-free initial examination, facilitates use of tourniquet if there are major bleeding wounds, and allows us to obtain good radiographs without an overlap of bones, which usually happens when the radiographs are taken within a bandage. Using the "On Arrival Block" system, emergency room assessment and resuscitation is bypassed. The patient is resuscitated only once, instead of twice. This avoids much duplication of effort, wasted time, patient suffering, unnecessary costs, and mistakes generated by miscommunication between 2 resuscitation teams. This can be done only in the place where all the resuscitative equipment and drugs are available. A senior anesthesiologist and surgeon must be available. The only contraindication is the suspicion of a brachial plexus injury, which can cause the local anesthetic to seep in through the open dural sleeve and cause total spinal anesthesia. "On Arrival Block" was set up at Ganga Hospital, Coimbatore, India, during the early 90s by the anesthesiologist Ravindra Bhat and the plastic surgeon Raja Sabapathy out of necessity, who recognized its value and made it the standard of care.

A combination of pathologies - facet joint synovial cyst, epidural lipomatosis and conjoined nerve root anomaly in the lumbar spine of a 45-year-old patient. A case report

Facet joint synovial cysts are abnormal fluid-filled cystic formations that develop from a degenerative process of the facet joints. Spinal epidural lipomatosis is a process of excessive accumulation of fat in the epidural space. Conjoined nerve root (CNR) anomaly refers to an anatomical variation in which two adjacent nerve roots share a common dural sleeve. The aforementioned three rare pathologies cause the same pathological process of stenosis, therefore compressing the nervous structures. A 45-year-old female patient was admitted to the Department of Neurosurgery with severe low back and radicular pain, and numbness along her left leg. Antalgic posture, painful paravertebral muscle tenderness, L4 radiculopathy, and L5 and S1 dermatome hypoesthesia on the left as well as positive straight leg raising sign (Laseque) were present upon examination. CT and MRI scanning showed stenosis on L4-L5 level caused by bilateral synovial cyst formation. Microsurgical decompression by foraminotomy at L4-L5 level on the left with dissection of the synovial cyst and epidural lipomatosis was performed. In the course of the operation CNR anomaly was discovered. The complete decompression alleviated the symptoms and after 3 uneventful postoperative days the patient was discharged. Spinal stenosis causing compression upon nervous structures is a process that could be caused by a number of conditions. The incidence of rare pathologies and anomalies or even the more rarely occurring combination of them must be considered on daily basis in the clinical practice in order to make the correct diagnosis and plan the best possible treatment for the patient.

Percutaneous Endoscopic Diskectomy using an Interlaminar Approach Based on 3D CT/MR Fusion Imaging.

With effective preoperative planning, percutaneous endoscopic diskectomy (PED) via an interlaminar approach (PED-IL) can reduce the need for partial laminectomy. Our aim was to assess the clinical outcomes of PED-IL, planned using three-dimensional fusion of computed tomography and magnetic resonance (3D CT/MR) images. Our retrospective analysis was based on data from 102 patients (66 were men) treated by PED-IL. Preoperative planning was based on the positional relationship between the nerve root and the lumbar disk herniation, visualized on 3D CT/MR fusion images through a simulated IL window. Two approaches were planned: type I, via a partial window opening of the ligamentum flavum, and type II, via a partial IL window opening and partial laminectomy. Decisions were then made to approach the herniation from the shoulder (subtype s) or axillary (subtype a) portion of the nerve, or we used a combination of both approaches (subtype a + s). Operative time and the pre- to postsurgical change in pain and pain-related disability scores (Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores) were evaluated. The number of cases in which the preoperative planned surgery was modified intraoperatively and the incidence of complications were also evaluated. A type I approach was planned in 30 cases (29.4%) and type II in 72 cases (70.6%). Intraoperative change from type I to type II was required in two cases. The mean operative time was longer for type II than type I procedures. Pain and pain-related disability scores improved in all patients, and only one case of dural sleeve damage was identified. Preoperative planning using a simulated IL window to visualize the 3D regional anatomy is effective in predicting the feasibility of a PED-IL.

A Case of Split Cord Malformation with Triple Bony Spur in a Single Dural Sleeve—A Classification Dilemma

AbstractSplit cord malformation-I (SCM-I) is characterized by the presence of double dural sacs, with rigid extradural bony/cartilaginous spur leading to symmetrical or asymmetrical division of the cord. In split cord malformation-II (SCM-II), there is a single dural sac with a nonrigid fibrous spur and symmetrical division of the cord. SCM-II are slightly more common than SCM-I, constituting around 50 to 60% of SCMs. The authors report a unique case of SCM with triple bony spurs lying both intra- and extradurally in a single dural sleeve. At the time of submission of this report, to the best of authors’ knowledge, no case of SCM with triple bony spurs in single dural sleeve has been reported anywhere in the world literature.

Timing, severity of deficits, and clinical improvement after surgery for spinal dural arteriovenous fistulas.

OBJECTIVE Spinal dural arteriovenous fistulas (dAVFs) are rare vascular abnormalities caused by arteriovenous shunting. They often form at the dural root sleeve between a radicular feeding artery and draining medullary vein causing venous congestion and edema, decreased perfusion, and ischemia of the spinal cord. Treatment consists of either surgical ligation of the draining vein or selective embolization via an endovascular approach. There is a paucity of data on which modality provides more durable and effective outcomes. METHODS The authors performed a retrospective review of a prospectively maintained database by the senior author to assess clinical outcomes in patients undergoing surgical treatment of spinal dAVFs. Preoperative and postoperative motor and Aminoff-Logue Scale (ALS) scores were collected. RESULTS A total of 41 patients with 44 spinal dAVFs were identified, with a mean patient age of 64 years. The mean symptom duration was 14 months, with weakness (82%), urinary symptoms (47%), and sensory symptoms (29%) at presentation. The fistula locations were as follows: 30 thoracic, 9 lumbar, 3 sacral, and 2 cervical. Five patients had normal motor and ALS scores at presentation. Among the remaining 36 patients with motor deficits or abnormal gait and micturition at presentation, 78% experienced an improvement while the remaining 22% continued to be stable. There was a trend toward improved outcomes in patients with shorter symptom duration; mean symptom duration among patients with clinical improvement was 13 months compared with 22 months among those without improvement. Additionally, rates of improvement were higher for lower thoracic and lumbosacral dAVFs (85% and 83%) compared with those in the upper thoracic spine (57%). No patient developed recurrent fistulas or worsening neurological deficits. CONCLUSIONS Surgery is associated with excellent outcomes in the treatment of spinal dAVFs. Early diagnosis and treatment are critical, with a trend toward improved outcomes. No patient in this study had fistula recurrence or worsening of symptoms. Among patients with abnormal motor or ALS scores, 78% improved after surgery. Therapeutic embolization is an option for some lesions, but for cases with unfavorable anatomy where embolization is not feasible, surgery is a safe option associated with high success.

Percutaneous endoscopic interlaminar lumbar discectomy for superiorly sequestrated disc L5–S1: A case report with technical review

L5-S1 disc has always been a difficult disc to target by rigid endoscope because of anatominal limitations .These limitation severely hampers transforaminal approach for superiorly migrated disc at L5-S1. We performed percutaneous endoscopic interlaminar lumbar decompression (PEILD) for removal of superiorly migrated sequestrated disc and preserved the functional structures. Through this approach nerve root and dural sleeve were exposed and adequate removal of migrated disc was done, which was also confirmed by immediate post operative MRI. The clinical outcome was evaluated using visual analogue scale (VAS) score and brief pain inventory (BPI) . We obtained excellent results in treating superiorly sequestrated disc at L5-S1 using endoscopic interlaminar angled approach.

Are Tarlov Cysts Being Identified and Reported on Lumbar Spine MRI Scan in Patients with Sciatica

Introduction Following advances in surgical technique sacral Tarlov Cysts (TCs) are now a treatable cause of back pain and sciatica.1,2 However many surgeons and radiologists still view them as an incidental finding. This audit was performed to raise awareness of TCs within the hospital and further afield, assess the extent to which TCs are present in patients with sciatica and assess if they are being identified and reported by the radiologist and surgeon in every case. Material and Methods Following a literature review a list of all spinal MRI scans requested by the three consultant spinal surgeons working at the hospital between 1/1/2013 – 31/12/2014 was compiled by the radiology department. All patients with complaints of radicular pain or altered sensation in one or both lower limbs in their initial clinic letter then had their MRI scan reviewed using the hospital PACS system for the presence of TCs. The radiologist's report and follow-up clinic letter were then reviewed in patients with a TC present on their scan to see if it was reported by the radiologist and surgeon. Any patient who's scan or clinic letters were not were removed from the audit. Results In total 1499 patients underwent lumbar-sacral MRI scan under the care of the spinal surgeons. Of these, 1070 fitted the inclusion criteria. 6 MRI scans were not accessible, in total 1064 MRI scans were reviewed for the presence of TCs. 158 scans showed sacral TCs present, an incidence of 14.85%. Of the 158 only 33 (21%) had TCs in the radiologists' report. 4 were reported as possibly symptomatic and the rest as an incidental finding. Only the 4 potentially symptomatic TC patients were notified of the presence of the cysts during their clinic appointment following the MRI scan. No other patients notified of the presence of TCs on their MRI. Therefore of the 158 patients with sacral TCs present only 4 (2.5%) were made aware of the lesion. Only one case of symptomatic cyst was identified as the patient's symptoms decreased following excision of the cyst. Conclusion Several things were apparent from the literature review; the exact anatomical area supplied by each of the lumbar-sacral dermatomes is not known and as such pathology compressing the S2 nerve root can cause symptoms suggestive of an S! or even L5 radiculopathy,3 TCs can be progressive in nature,4 microsurgical treatment gives the best relief of symptoms and can give complete relief of symptoms,5,6 early intervention gives the best prognosis.1 From the audit it was apparent that in almost 80% of cases TCs were not being reported, this could potentially lead to patients continuing with symptoms, or developing them as the cyst progresses. A delay in diagnosis and therefore treatment of a symptomatic TC could lead to a poorer prognosis. It seems that for many Tarlov Cysts are still viewed as an asymptomatic incidental finding, until this opinion is changed it will continue to be under reported and patients will continue to suffer a potentially treatable spinal pathology. References Sun JJ, Wang ZY, Teo M, et al. Comparative outcomes of the two types of sacral extradural spinal meningeal cysts using different operation methods: a prospective clinical study. PLoS ONE 2013;8(12):e83964 Lucantoni C, Than KD, Wang AC, et al. Tarlov cysts: a controversial lesion of the sacral spine. Neurosurg Focus 2011;31(6):E14 Turek S. Orthopaedics: Principles and Their Application. 3rd ed. Philadelphia: JB Lippincott; 1977 Freidenstein J, Aldrete JA, Ness T. Minimally invasive interventional therapy for Tarlov cysts causing symptoms of interstitial cystitis. Pain Physician 2012;15(2):141–146 Caspar W, Papavero L, Nabhan A, Loew C, Ahlhelm F. Microsurgical excision of symptomatic sacral perineurial cysts: a study of 15 cases. Surg Neurol 2003;59(2):101–105, discussion 105–106 Neulen A, Kantelhardt SR, Pilgram-Pastor SM, Metz I, Rohde V, Giese A. Microsurgical fenestration of perineural cysts to the thecal sac at the level of the distal dural sleeve. Acta Neurochir (Wien) 2011;153(7):1427–1434, discussion 1434

Biological modalities for treatment of acute spinal cord injury: a pilot study and review of the literature

ObjectiveParaplegia due to traumatic spinal cord injuries is one of the devastating effects of dorsolumbar vertebral fractures. Treatment modalities for such fractures, such as stabilization, have no effect on the neurological recovery. Thus, various pharmacological and biological treatment modalities have been used. The more recent trend of using autologous stem cells from the iliac crest has been used in some clinical trials with varying success. Thus, more clinical studies are required to study the effect of this novel approach MethodsThis is a prospective hospital-based cohort study (level IV). The study was conducted in the Dept. of Orthopaedics, University College of Medical Sciences and GTB Hospital, Delhi from November 2010 to March 2012. Ten patients who had sustained traumatic dorsolumbar vertebral fractures with complete paraplegia were recruited for this study. Under suitable anaesthesia, at the beginning of surgery, 100ml of bone marrow was aspirated. This was centrifuged and buffy coat isolated and then transferred into a sterile tube and sent to the operating room on ice packs. After surgical decompression and stabilization, the buffy coat isolate was injected into the dural sleeve at the site of the injury using a 21G needle. All the patients were evaluated for neurological improvement using the American Spinal Injury Association (ASIA) score and Frankel grade at 6weeks and 3months postoperatively. ResultsThe evaluation at 6weeks showed some improvement in terms of the ASIA scores in 2 patients but no improvements in their Frankel Grade. The other 8 patients showed no improvements in their ASIA scores or their Frankel Grades. The current pilot study has shown that there has been no improvement in most of the recipients of the transplant (n=8). Some patients (n=2) who did show some improvement in their sensory scores proved to be of no significant functional value as depicted by no change in their Frankel Grades. ConclusionThe outcome of current study shows that although this modality of treatment is safe for the patients, it provides no additional benefits on improvement of quality of life among these patients.

Safety of thrust joint manipulation in the thoracic spine: a systematic review

Background:There appears to be very little in the research literature on the safety of thrust joint manipulation (TJM) when applied to the thoracic spine.Purpose:To retrospectively analyze all available documented case reports in the literature describing patients who had experienced severe adverse events (AE) after receiving TJM to their thoracic spine.Data Sources:Case reports published in peer reviewed journals were searched in Medline (using Ovid Technologies, Inc.), Science Direct, Web of Science, PEDro (Physiotherapy Evidence Database), Index of Chiropractic literature, AMED (Allied and Alternative Medicine Database), PubMed and the Cumulative Index to Nursing and Allied Health (CINHAL) from January 1950 to February 2015.Study Selection:Case reports were included if they: (1) were peer-reviewed; (2) were published between 1950 and 2015; (3) provided case reports or case series; and (4) had TJM as an intervention. Articles were excluded if: (1) the AE occurred without TJM (e.g. spontaneous); (2) the article was a systematic or literature review; or (3) it was written in a language other than English or Spanish.Data Extraction:Data extracted from each case report included: gender; age; who performed the TJM and why; presence of contraindications; the number of manipulation interventions performed; initial symptoms experienced after the TJM; as well as type of severe AE that resulted.Results:Ten cases, reported in 7 case reports, were reviewed. Cases involved females (8) more than males (2), with mean age being 43.5 years (SD=18.73, Range = 17 -71). The most frequent AE reported was injury (mechanical or vascular) to the spinal cord (7/10), with pneumothorax and hematothorax (2/10) and CSF leak secondary to dural sleeve injury (1/10).Limitations:There were only a small number of case reports published in the literature and there may have been discrepancies between what was reported and what actually occurred, since physicians dealing with the effects of the AE, rather than the clinician performing the TJM, published the cases.Conclusions:Serious AE do occur in the thoracic spine, most commonly, trauma to the spinal cord, followed by pneumothorax. This suggests that excessive peak forces may have been applied to thoracic spine, and it should serve as a cautionary note for clinicians to decrease these peak forces.

The anaesthetic management of patient with amiodarone-induced thyrotoxicosis posted for thyroidectomy.

Sir, A 44-year-old male, case of arrhythmogenic right ventricular dysplasia was on treatment with tablet amiodarone 200 mg/day. After 2 years of treatment, he developed breathlessness, fatigability, increased appetite, tremors, and loss of weight. There was no thyroid swelling, but thyroid function tests were showing raised T3, T4 and decreased thyroid stimulating hormone. Thyroid scintigraphy and MIBI scan were suggestive of destructive thyroiditis. He was diagnosed to be suffering from mixed type amiodarone-induced thyrotoxicosis (AIT) and was treated with carbimazole and prednisolone, with no response to treatment. Amiodarone was stopped, but the patient was not relieved of symptoms for 4 months and hence total thyroidectomy was planned. Pre-operative electrocardiogram showed right bundle branch block, two-dimensional echocardiography showed left ventricular ejection fraction of 60% with right ventricular free wall thinning. Pulmonary function tests were done to rule out pulmonary toxicity. High-risk consent was taken, and the patient was pre-medicated with tablet metoprolol and injection dexamethasone. Pre-induction blood pressure was 150/94 mmHg with a pulse rate of 100/min and regular. Automated external defibrillator pads were attached in an anterolateral position to provide emergency defibrillation without disturbing surgical field drapes. After giving injection midazolam and fentanyl, right radial artery and left antecubital vein were cannulated under local anaesthesia. Invasive monitoring was done since the pre-induction period for early recognition of thyroid storm and cardiac failure. Cold intravenous fluids were infused and arterial blood gas monitoring was started. For pre-emptive analgesia, ultrasound-guided bilateral superficial and deep cervical plexus block was performed with 20 ml of 0.25% bupivacaine (5 ml at each point) to avoid stimulation due to thyroid handling and thus reduce requirement of analgesics and for post-operative analgesia. Anaesthesia was induced with injection propofol and vecuronium. Proseal® laryngeal mask airway (LMA) No. 4 was inserted and anaesthesia was maintained with oxygen, nitrous oxide and isoflurane. At the end of surgery, skeletal muscle paralysis was reversed, LMA removed, and patient shifted to Intensive Care Unit. In the post-operative period, oral metoprolol was continued with tapering doses of steroids. Serum calcium and thyroid function tests were monitored. Amiodarone is a class III antiarrhythmic drug used in the treatment of recurrent severe ventricular and supraventricular arrhythmias.[1] Due to structural similarity with thyroid hormone, 14–18% of patients develop overt thyroid dysfunction.[2] Depending on dietary iodine content, it can be either AIT or amiodarone induced hypothyroidism. AIT is classified as type 1 (pre-existing thyroid disease) and type 2 (destructive thyroiditis), but mixed forms frequently exist.[2] This classification does not affect the clinical outcome, but it is required for medical treatment. Type 1 is treated with methimazole and potassium perchlorate and type 2 with glucocorticoids.[1] There is controversy regarding the further continuation of amiodarone. Withdrawal can cause rebound rise in tri-iodothyronine. Due to long half-life thyrotoxic symptoms persists for months.[1] Before withdrawing amiodarone, underlying cardiac condition and availability of other antiarrhythmic agents or any cardiac intervention should be considered. Dronedarone is a congener of amiodarone. It is as potent as amiodarone and without any adverse effects.[3] (Automatic internal cardioverter-defibrillator) is a good option, but it is costly. Therapeutic options for refractory cases of AIT include radioiodine, plasmapheresis and surgery.[4] Radioiodine inhibits the peripheral conversion of T4 to T3, but not feasible due to destructive changes. Plasmapheresis is costly, and the effect is transient.[5] When a patient does not respond to medical management, total thyroidectomy is considered. Total thyroidectomy is performed under general or local anaesthesia with sedation. Local anaesthesia is good for the critically ill patient when operated by the experienced surgeon for faster recovery. Snyder et al. have found similar results and patient satisfaction for both types of anaesthesia.[6] Anaesthesia management of such patient is a high-risk scenario. We have to take into consideration underlying cardiac condition, possibility of thyroid storm because of uncontrolled thyrotoxicosis and effects of amiodarone on other systems of the body. While managing this patient, we have to avoid haemodynamic stress response related to intubation, extubation and thyroid handling, maintain fluid electrolyte balance, normothermia and good pain relief. Use of Proseal® LMA and pre-emptive analgesia with ultrasonography (USG) guided a cervical plexus block is a novel approach for managing this type of patients. Proseal® LMA is less likely to elicit a catecholaminergic stress response to laryngoscopy, intubation and extubation, but its drawback is that it can get displaced during retraction of trachea and thyroid handling. Though bilateral cervical plexus blocks are deferred, USG guided block is safe and allows for less volume of local anaesthetic to be used. It avoids complications like a puncture of vertebral artery and deposition near the dural sleeve. For stable haemodynamics and faster recovery, cardio-stable and short-acting anaesthetic and relaxant drugs are preferred. Post-operatively, patients must be monitored because of the risk of hypothyroidism and hypocalcemia.

Definition of the to be named ligament and vertebrodural ligament and their possible effects on the circulation of CSF.

Few studies have been conducted specifically on the dense connective tissue located in the posterior medial part of the cervical epidural space. This study was undertaken to examine the presence of this connection between the cervical dura mater and the posterior wall of spinal canal at the level of C1–C2. 30 head-neck specimens of Chinese adults were used. Gross dissection was performed on the suboccipital regions of the 20 specimens. Having been treated with the P45 plastination method, 10 specimens were sliced (9 sagittal and 1 horizontal sections). As a result, a dense fibrous band was identified in the nuchal ligament of 29 specimens (except for one horizontal section case). This fascial structure arose from the tissue of the posterior border of the nuchal ligament and then projected anteriorly and superiorly to enter the atlantoaxial interspace. It was termed as to be named ligament (TBNL). In all 30 specimens the existence of a fibrous connection was found between the posterior aspect of the cervical dura mater and the posterior wall of the spinal canal at the level of the atlas to the axis. This fibrous connection was identified as vertebrodural ligament (VDL). The VDL was mainly subdivided into three parts, and five variations of VDL were identified. These two structures, TBNL and VDL, firmly link the posterior aspect of cervical dura mater to the rear of the atlas-axis and the nuchal region. According to these findings, the authors speculated that the movements of the head and neck are likely to affect the shape of the cervical dural sleeve via the TBNL and VDL. It is hypothesized that the muscles directly associated with the cervical dural sleeve, in the suboccipital region, may work as a pump providing an important force required to move the CSF in the spinal canal.

Minimally invasive convection-enhanced delivery of biologics into dorsal root ganglia: validation in the pig model and prospective modeling in humans. Technical note.

Dorsal root ganglia (DRG) are critical anatomical structures involved in nociception. Intraganglionic (IG) drug delivery is therefore an important route of administration for novel analgesic therapies. Although IG injection in large animal models is highly desirable for preclinical biodistribution and toxicology studies of new drugs, no method to deliver pharmaceutical agents into the DRG has been reported in any large species. The present study describes a minimally invasive technique of IG agent delivery in domestic swine, one of the most common large animal models. The technique utilizes CT guidance for DRG targeting and a custom-made injection assembly for convection enhanced delivery (CED) of therapeutic agents directly into DRG parenchyma. The DRG were initially visualized by CT myelography to determine the optimal access route to the DRG. The subsequent IG injection consisted of 3 steps. First, a commercially available guide needle was advanced to a position dorsolateral to the DRG, and the dural root sleeve was punctured, leaving the guide needle contiguous with, but not penetrating, the DRG. Second, the custom-made stepped stylet was inserted through the guide needle into the DRG parenchyma. Third, the stepped stylet was replaced by the custom-made stepped needle, which was used for the IG CED. Initial dye injections performed in pig cadavers confirmed the accuracy of DRG targeting under CT guidance. Intraganglionic administration of adeno-associated virus in vivo resulted in a unilateral transduction of the injected DRG, with 33.5% DRG neurons transduced. Transgene expression was also found in the dorsal root entry zones at the corresponding spinal levels. The results thereby confirm the efficacy of CED by the stepped needle and a selectivity of DRG targeting. Imaging-based modeling of the procedure in humans suggests that IG CED may be translatable to the clinical setting.

Pseudomeningocele after Traumatic Nerve Root Avulsion

Traumatic brachial plexus complete avulsions and the subsequent formation of pseudomeningoceles are a well-known entity that usually remains asymptomatic. Pseudomeningocele is due to the dural sleeve encasing the damaged roots and the spinal liquid that may accumulate locally or in the supraclavicular soft tissues. The pseudomeningocele, added to the associated lesion of the plexus and usually the surrounding vessels, may become difficult to manage. We describe the novel management of a traumatic pseudomeningocele using an endovascular technique.

Dermoid cyst of the lateral wall of the cavernous sinus presenting with isolated abducens nerve palsy

Dear Editor,Dermoid cysts are rare congenital slow growing neoplasmsaccounting for less than 1 % of intracranial tumors [2].Dermoid cysts confined to the lateral wall of the cavernoussinus are extremely unusual and clinical symptoms general-ly occur late in the course of tumor growth, due to localirritative effects of the space-occupying lesion. The mostcommon clinical presentation results from involvement ofthe cranial nerves contained in the lateral wall of the cav-ernous sinus. Accordingly, while trigeminal nerve dysfunc-tion, oculomotor and trochlear nerve palsies with dermoidorigin have been widely described [1, 5], isolated abducensnerve deficit, to the best of our knowledge, has not beenpreviously reported.A 37-year-old man presented with a 1-week history ofprogressive diplopia. On the first examination, a remarkablelimitation in abduction in his right eye was observed (Fig. 1).Magneticresonanceimaging(MR)demonstratedacysticovalshaped lesion in the right parasellar space hypointense tohyperintense on T1- and T2-weighted images, whichpresented a slight rim of enhancement after contrast injection(Fig. 1). The posterior vertical segment and the posteriorbend of the intracavernous carotid artery were displacedantero-medially (Fig 1). Analysis of MR images suggestedthat the tumor was an interdural dermoid cyst of the lateralwall of the cavernous sinus.The patient underwent a right fronto-temporal cranioto-my for intradural resection of the tumor, which was ob-served bulging into and deforming the lateral wall of thecavernous sinus. The outer (or meningeal) layer of thelateral wall was incised over the most prominent part ofthe tumor, and its greasy content associated with hair tuftswas progressively removed. The capsule adherent to theinner (or membranous) layer of the lateral wall of the cav-ernous sinus was dissected and removed in a piecemealfashion.Histopatological examination confirmed that the tumorwas a dermoid cyst.The patient’s postoperative recovery was uneventful. Atthe 1-month follow-up examination, diplopia had resolvedand MR images obtained at this time revealed total tumorresection (Fig. 1).Interdural dermoid cysts of the lateral wall of the cavern-ous sinus have been rarely reported in the literature [1, 5].The lateral dural wall of the cavernous sinus is composed oftwo layers, the outer layer (meningeal layer or dura propria)and the inner membranous layer (or endosteal layer), whichis formed by the dural sleeves of CN III, IVand V1 [3, 7].According to this meningeal architecture, interduraldermoid cysts generally induce symptoms due to involve-ment of the ophthalmic division of the trigeminal nerve,oculomotor nerve and trochlear nerve [1, 5]. In the present

Autopsy Proven Peripheral Nervous System Neurolymphomatosis Despite Negative Bilateral Sural Nerve Biopsy

Neurolymphomatosis (NL) refers to a lymphomatous infiltration of peripheral nerves associated with central nervous system or systemic lymphoma, or alternatively, neurodiagnostic evidence of nerve enhancement and/or enlargement beyond the dural sleeve in the setting of primary central nervous system lymphoma or systemic lymphoma. NL is a rare complication of systemic cancer with heterogeneous clinical presentations and an elusive diagnosis. Diagnosis usually requires the demonstration of infiltrating malignant lymphocytes in the peripheral nerve. Infiltration of brain parenchyma, meninges or Virchow–Robin spaces is characteristic of systemic disease at autopsy. We describe a patient presenting with biopsy negative NL affecting exclusively the peripheral nervous system at autopsy.

Spinal cord injury from electrocautery: observations in a porcine model using electromyography and motor evoked potentials

We have previously investigated electromyographic (EMG) and transcranial motor evoked potential (MEP) abnormalities after mechanical spinal cord injury. We now report thermally generated porcine spinal cord injury, characterized by spinal cord generated hindlimb EMG injury activity and spinal cord motor conduction block (MEP loss). Electrocautery (EC) was delivered to thoracic level dural root sleeves within 6-8 mm of the spinal cord (n = 6). Temperature recordings were made near the spinal cord. EMG and MEP were recorded by multiple gluteobiceps intramuscular electrodes before, during, and after EC. Duration of EC was titrated to an end-point of spinal motor conduction block (MEP loss). In 5/6 roots, ipsilateral EMG injury activity was induced by EC. In 4/5 roots, EMG injury activity was identified before MEP loss. In all roots, a minimum of 20 s EC and a temperature maximum of at least 57 °C at the dural root sleeve were required to induce MEP loss. Unexpectedly, conduction block was preceded by an enhanced MEP in 4/6 trials. EMG injury activity, preceding MEP loss, can be seen during near spinal cord EC. Depolarization and facilitation of lumbar motor neurons by thermally excited descending spinal tracts likely explains both hindlimb EMG and an enhanced MEP signal (seen before conduction block) respectively. A thermal mechanism may play a role in some unexplained MEP losses during intraoperative monitoring. EMG recordings might help to detect abnormal discharges and forewarn the monitorist during both mechanical and thermal injury to the spinal cord.