Nerve Sleeve Research Articles

Wrapping a man-made dura around reconstructed nerve sleeve avoid residue or recurrence of sacral Tolav cysts

Abstract Objective To evaluate the therapy effect on patients with sacral extradural meningeal cysts with nerve root fibers by wrapping a man-made dura around reconstructed nerve sleeve. Patients and methods In order to avoid the cysts residue and recurrence postoperative, wrapping a man-made dura around reconstructed nerve sleeve, a new operating method, was performed in 24 patients with 42 cysts. After the nerve sleeve being reconstructed, wrapping and suturing a man-made dura around the nerve sleeve was performed. The Improved Japanese Orthopedic Association (IJOA) scoring system was used to evaluate preoperative and postoperative neurological function. Results Among 24 patients, 14 were females, and 10 males. Three-month after open surgery, no cyst residue or recurrence was grasped in any patient. The mean IJOA score was 18.8 ± 1.32 preoperatively and 19.6 ± 0.65 postoperatively, which was a significant difference between the preoperative and postoperative scores (t = −3.82, P = 0.001). These results indicate a significant improvement in neurological function after surgery. Conclusion Based on reconstruction the nerve sleeve, wrapping with man-made dura and forming double nerve sleeve was safety and effective operating method for treatment the sacral extradural meningeal cysts with nerve root fibers.

Falcotentorial Location of Dural Arteriovenous Fistulas Derived from theNeural Crest as aRisk Factor for Aggressive Clinical Course.

The topographical distribution of dural arteriovenous fistulas (DAVFs) was analyzed based on the embryological anatomy of the dural membrane. Sixty-six consecutive cases of intracranial and spinal DAVFs were analyzed based on the angiography, and each shunt point was identified according to the embryological bony structures. The area of dural membranes was categorized into three different groups: a ventral group located on the endochondral bone (VE group), a dorsal group on the membranous bone (DM group), and a falcotentorial group (FT group) in the falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma sellae. The FT group was derived from the neural crest and designated when the dural membrane was formed only with the dura propria (meningeal layer of the dura mater) and not from the endosteal dura. Olfactory groove, falx, tent of the cerebellum, and nerve sleeve of spinal cord were categorized in the FT group, which presented later in life and which had a male predominance, more aggressive clinical presentations, and significant cortical and spinal venous reflux. The FT group was formed only with the dura propria that was considered as an independent risk factor for aggressive clinical course and hemorrhage of DAVFs.

Balloon-Assisted Fistula Sealing Procedure for Symptomatic Tarlov Cysts

Tarlov cyst is an abnormal expansion of the spinal nerve sleeve, and it communicates with the subarachnoid cavity via a perineural fistula. This study presents our experience of a balloon-assisted fistula sealing procedure in treating Tarlov cyst. Twenty-two patients with symptomatic Tarlov cysts were surgically treated. An emulsion balloon was placed into the lumbar subarachnoid cistern through a trocar, so as to temporarily block cerebrospinal fluid flow, then the thecal sac was opened and the inlet of the fistula was sealed by suture of a muscular patch and reinforced by fibrin glue. Finally, the cyst wall was imbricated and the bony cavity was filled with pedicled muscle flaps. Comparing the preoperative and postoperative pain scores according to visual analog scale, 2 patients were slightly improved and 18 patients were substantially improved, including 3 completely pain-free cases. Only 2 patients were unchanged in pain, and both of them had multiple cysts. As a whole, the postoperative pain score was much better than the preoperative score (2.4 vs. 7.5; P < 0.01). Bladder weakness was slightly improved, and bowel dysfunction was almost unchanged after operation. During follow-up, cyst recurrence was found in 1 patient. The balloon-assisted fistula sealing procedure is safe and effective for Tarlov cyst, especially for the single cyst. It is a good complement to the cyst wall imbricating procedure.

Embryological Consideration of Dural Arteriovenous Fistulas.

The topographical distribution of dural arteriovenous fistulas (DAVFs) was analyzed based on the embryological anatomy of the dural membrane. Sixty-six consecutive cases of intracranial and spinal DAVFs were analyzed based on the angiography, and each shunt point was identified according to the embryological bony structures. The area of dural membranes was categorized into three different groups: a ventral group located on the endochondral bone (VE group), a dorsal group located on the membranous bone (DM group) and a falcotentorial group (FT group) located in the falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragm sellae. The FT group was designated when the dural membrane was formed only with the dura propria (meningeal layer of the dura mater) and not from the endosteal dura. Cavernous sinus, sigmoid sinus, and anterior condylar confluence was categorized to VE group, which had a female predominance, more benign clinical presentations, and a lower rate of cortical and spinal venous reflux. Transverse sinus, confluence, and superior sagittal sinus belonged to the DM group. Olfactory groove, falx, tent of the cerebellum, and nerve sleeve of spinal cord were categorized to the FT group, which presented later in life and which had a male predominance, more aggressive clinical presentations, and significant cortical and spinal venous reflux. The DAVFs was associated with the layers of the dural membrane characterized by the two different embryological bony structures. The FT group was formed only with the dura propria as an independent risk factor for aggressive clinical course and hemorrhage of DAVFs.

Use of nerve elongator to repair short-distance peripheral nerve defects: a prospective randomized study.

Repair techniques for short-distance peripheral nerve defects, including adjacent joint flexion to reduce the distance between the nerve stump defects, “nerve splint” suturing, and nerve sleeve connection, have some disadvantages. Therefore, we designed a repair technique involving intraoperative tension-free application of a nerve elongator and obtained good outcomes in the repair of short-distance peripheral nerve defects in a previous animal study. The present study compared the clinical outcomes between the use of this nerve elongator and performance of the conventional method in the repair of short-distance transection injuries in human elbows. The 3-, 6-, and 12-month postoperative follow-up results demonstrated that early neurological function recovery was better in the nerve elongation group than in the conventional group, but no significant difference in long-term neurological function recovery was detected between the two groups. In the nerve elongation group, the nerves were sutured without tension, and the duration of postoperative immobilization of the elbow was decreased. Elbow function rehabilitation was significantly better in the nerve elongation group than in the control group. Moreover, there were no security risks. The results of this study confirm that the use of this nerve elongator for repair of short-distance peripheral nerve defects is safe and effective.

Sensory regeneration in dorsal root avulsion.

Brachial as well as lumbosacral plexus avulsion injuries are usually caused by high kinetic traumas, such as car-pedestrian, car and motorcycle accidents or falls from great heights. Traction forces affecting the head and shoulders or extremities pull the spinal nerve sleeves away from the spinal cord and rupture the postganglionic spinal root from the cord. In so called central avulsion injuries, the spinal root is avulsed at the interface between the central and peripheral nervous system (CNS and PNS). This results not only in the disconnection of the root from the cord but also in a longitudinal spinal cord injury. The complexity of the injury leads to degeneration of the spinal root and a marked inflammatory response of the spinal cord followed by the formation of a glial scar (Kachramanoglou et al., 2011).

Collagen nerve protector in rat sciatic nerve repair: A morphometric and histological analysis

Peripheral nerve repair is often complicated by fibroblastic scar formation, nerve dysfunction, and traumatic neuroma formation. Use of bio-absorbable protective wraps may improve outcomes of these repairs. This study histologically compared the incidence of neuroma formation, connective tissue proliferation, and axonal regrowth in transected rat sciatic nerves repaired with and without tubular collagen nerve sleeves. Twenty Sprague-Dawley rats underwent unilateral sharp sciatic nerve transection and microscopic nerve repair with four epineural sutures and were randomly treated with or without an encircling collagen nerve sleeve. Normal nerves from the contralateral sciatic nerve were also examined. At sacrifice three months later, the nerves were evaluated for traumatic neuroma formation, perineural scar formation, and morphometric analysis. Histological examination of normal and repaired nerves by a neuropathologist demonstrated healing, minimal Wallerian degeneration and no traumatic neuroma formation. Distal section analysis (nine nonwrapped, 10 wrapped), revealed no significant differences in total fascicular area, myelinated fibers per nerve, fiber density, myelin area per nerve, myelinated fiber diameter, axon diameter, myelin thickness, or G-ratio. Significantly greater (P = 0.005) inner epineural connective tissue formation was observed in nonwrapped nerves (0.62 mm(2) +/- 0.2) versus wrapped nerves (0.35 mm(2) +/- 0.16). The ratio of connective tissue to fascicular area was larger in nonwrapped (1.08 +/- 0.26) versus wrapped nerves (0.63 +/- 0.22) (P < 0.001). This study demonstrated decreased inner epineural connective tissue formation with use of a collagen nerve wrap during primary repair of peripheral nerve transection in a rat sciatic nerve model.

MRI diagnosis of brachial plexus preganglionic injury

Objective To evaluate MRI in diagnosing brachial plexus preganglionic injury.Methods Twenty cases with brachial plexus preganglionic injury underwent M R scanning before operation.MR imaging was obtained by GE Signa EXCITE 1.5 T scanner.The scanning sequences included SE T1 WI,FSE T2 WI,T2 WI STIR and 3D Fast imaging employing steady state with phase cycled(3D-FIESTA-c).All the patients had exploration of the supraclavicular plexus and electrophysiology examination. And the accuracy, sensitivity and specificity of MRI in diagnosing preganglionic brachial plexus iniury were calculated with the standards of surgical and EMG results.Results Among the 73 pairs of i,jured roots.MR imaging detected the abnormalities in 63 pairs.The accuracy, sensitivity and specificity of MRI in diagnosing preganglionic brachial plexus injury were 86.5/(83/96),86.3/(63/73).87.0/(20/23),respectively.The direct signs of brachial plexus preganglionic injury included (1) lack or mutilation of netwe root in 54 pairs (85.7/),(2)coarsening,bending,stiff course and unable to be traced to the intervertebral foramen continuously in 9 pairs (14.3/).The indirect signs included (1)cystic cerebrospinal fluid gathering in the vertebral canal,posttraumatic spinal meningocele in 46 pairs (73.0/),(2)abnormal shape of nerve sleeve in 13 pairs(20.6/),(3)displacement and deformity of spinal cord in 50 pairs(79.4/),(4)abnormal signal of paravertebral muscles in 1 9 patients.Conclusion MRI can distinctly show the nerve rootlets within the vertebral canal,so it is helpful in making a correct diagnosis of brachial plexus preganglionic injuries. Key words: Brachial plexus neuropathies; Diagnosis; Magnetic resonance imaging

Human spinal arachnoid villi revisited: immunohistological study and review of the literature

Few have described the relationship between arachnoid protrusions (villi) and adjacent spinal radicular veins, and the descriptions that do exist are conflicting. Some authors have even denied the presence of spinal arachnoid villi, suggesting that they play no role in cerebrospinal fluid (CSF) absorption. To further elucidate these structures, laminectomies from C-2 inferiorly to S-2 were performed in 10 fresh human adult cadavers. Following removal of the laminae, the dural nerve sleeves were identified and the spinal nerves excised 1 cm lateral and medial to the intervertebral foramina. Samples were submitted for histological and immunohistological analysis. The authors identified arachnoid villi in all specimens. The length of these structures was approximately 50 to 170 microm. Regionally, these villi were more concentrated in the lumbar region, but they were not present at every vertebral level, with observed skip zones. Occasionally, more than one villus was identified per vertebral level. The majority of villi were intimately related to an adjacent radicular vein. There was a direct relationship between the size of the adjacent radicular vein, and the presence and number of arachnoid villi. Findings in the present study have demonstrated that arachnoid villi exist and are morphologically associated with radicular veins. These data support the theory that CSF absorption occurs not only intracranially but also along the spinal axis. Further animal studies are necessary to prove that CSF traverses these villi and is absorbed into the spinal venous system.

Observations at the craniocervical junction with simultaneous caudal traction of the spinal cord

Some have opined that caudal traction of the spinal cord may result in caudal descent of the hindbrain. In fresh adult cadavers (n = 12; less than 6 h postmortem) with no CIM, distal tension (75 N) was applied to the conus medullaris with simultaneous observation of the cervical spinal cord, brainstem, and hindbrain and their relationship to the foramen magnum per occipital craniectomy and removal of the posterior arch of C1. After lumbar laminectomy in cadavers, caudal tension on the cord (conus medullaris) demonstrated negligible movement (less than 1 mm) of the caudal brain stem and cervical spinal cord. No movement of the cerebellar tonsils was identified. Moreover, after transection of the lumbar dural cul-de-sac and lumbar spinal dural nerve sleeves, distal traction produced only 2 to 3 mm of caudal descent of the brain stem and cervical spinal cord. Again, no movement of the cerebellar tonsils was visualized. Our findings in a fresh cadaveric model suggest that it is unlikely that caudal fixation of the distal spinal cord results in inferior displacement of the cerebellar tonsils, and a resultant Chiari I malformation or that transection of the filum terminale may reverse tonsillar ectopia. In vivo animal studies are now necessary to verify our findings.

Detailed anatomy of the intracranial segment of the hypoglossal nerve: neurovascular relationships and landmarks on magnetic resonance imaging sequences.

The thin hypoglossal nerve can be very difficult to distinguish on magnetic resonance (MR) images. The authors used a combination of sequences to increase the reliability of MR imaging in its demonstration of the 12th cranial nerve as well as to assess the course of the nerve, display its relationships to adjacent vessels, and provide landmarks for evaluating the nerve in daily practice. The study group consisted of 34 volunteers (68 nerves) in whom a three-dimensional (3D) Fourier-transformation constructive interference in steady-state (CISS) sequence and a 3D T1-weighted contrast-enhanced magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) sequence were applied. Two trained neuroradiologists collaboratively identified the hypoglossal trigone, preolivary sulcus, 12th cranial nerve, posterior inferior cerebellar artery, vertebral artery, 12th nerve root sleeve, and the hypoglossal canal on each side. The 3D CISS sequence successfully demonstrated the hypoglossal trigone (100% of images), 12th nerve root bundles (100% of images), and 12th nerve sleeves (88.2% of images). The canalicular segment was exhibited with the aid of plain 3D CISS sequences in 74% of images and by using contrast-enhanced 3D CISS sequences and contrast-enhanced MPRAGE sequences in 100% of images. The landmarks that proved useful to identify the cisternal segment of the 12th cranial nerve included the hypoglossal trigone, preolivary sulcus, and 12th nerve root sleeve. Neurovascular contact was identified in 61% of root bundles. The roots were distorted in 44% of these contacts. The contrast-enhanced 3D CISS sequence consistently displayed the cisternal segment as well as the canalicular segments of the hypoglossal nerve and is, therefore, the best sequence to visualize the complete cranial course of this nerve. Landmarks such as the 12th nerve sleeves can assist in the identification of this nerve.

Lateral thoracic meningocele

A case of intrathoracic meningocele is reported, and 95 cases from the literature are reviewed. Thoracic meningoceles are usually associated with neurofibromatosis; nevertheless their etiology remains controversial. The authors postulate the role of spinal trauma in some patients and the origin of the meningocele from an abnormal prolongation of a nerve sleeve in nontraumatic cases. Thoracic meningoceles often are asymptomatic or produce radicular intercostal pain. Spinal computed tomography is the most useful investigation, particularly in the exploration of large meningoceles. Surgery is required in symptomatic cases and usually results in remission of the pain.