Paraganglioma of the sacral spinal canal.

Paragangliomas are tumors arising in the paraganglia. Involvement of the spine is less common, and usually takes the form of intradural compression of the cauda equina. We report here a case of a 60-year-old man with recurrent and progressive pain of his sacral and perineal area, accompanied by occasional rod and perineal hypoesthesia on admission. He underwent laminectomies of the vertebral bodies S1 and S2, and an en bloc resection of the tumor. Postoperative histopathological examination revealed a paraganglioma. Postoperative staging showed no pathological abnormalities, and no tumor recurrence after one year. Even though rare, the paraganglioma of the sacral spinal canal should be considered in the differential diagnosis of tumors occurring in the spine.

Natural history of supratentorial hemangioblastomas in von Hippel-Lindau disease.

BACKGROUND: Supratentorial hemangioblastomas are rare lesions, occurring either sporadically or in von Hippel-Lindau disease. OBJECTIVE: Following recent advances in our understanding of the natural history of von Hippel-Lindau-associated cerebellar and spinal hemangioblastomas, we conducted a study of the natural history of supratentorial hemangioblastomas in von Hippel-Lindau disease. METHODS: We reviewed a series of 18 supratentorial hemangioblastomas in 13 patients with von Hippel-Lindau disease. Clinical, genetic, and serial imaging data and operative records were analyzed. RESULTS: Hemangioblastomas were most commonly seen in the temporal lobe. Only 6 tumors had a cyst at diagnosis or during follow-up, and only 6 patients had associated symptoms at presentation or during follow-up. The most frequent clinical presentations were intracranial hypertension and visual loss. Of 14 tumors with documented serial imaging, 13 demonstrated tumor growth. Rates and patterns of tumor growth were unique to each patient. The mechanism of cyst formation described in other locations was also demonstrated in the supratentorial region. Patterns of peritumoral edema and rate of cyst formation seemed to be influenced by the presence of anatomic barriers. Germline VHL mutation was identified in all patients, but no specific genotype-phenotype correlation was found, although a familial predisposition is suggested. CONCLUSION: This series illustrates the wide variation in tumor locations, patterns of growth, and edema progression seen in supratentorial hemangioblastomas and adds to our knowledge of the natural history of hemangioblastomas.

Surgical treatment of posttraumatic syringomyelia.

OBJECTIVE: The present study evaluates the effectiveness of 2 surgical procedures, shunting and untethering, for posttraumatic syringomyelia. METHODS: We retrospectively reviewed the medical charts of all surgical patients with posttraumatic syringomyelia in our department. Shunting was performed before 1997; after 1997, we used arachnoidolysis and untethering. RESULTS: Shunting was performed in 15 patients, and 19 patients underwent arachnoidolysis. Statistical analysis found that the 2 groups did not differ in age or initial clinical or radiological presentation. All patients suffered from progressively worsening symptoms. Reconstruction of the subarachnoid space by arachnoidolysis and untethering the cord allowed us to improve or stabilize 94% of our patients. Shunting exposed the patients to a higher rate of clinical recurrence and reoperation. Comparisons between the 2 groups found a significant difference (better results) in favor of arachnoidolysis for the McCormick classification (P = .03), American Spinal Injury Association motor score of the lower extremities (P = .02), and subjective grading (P = .001). There was no significant difference in the evolution of pain or the Vaquero index between the 2 groups; however, a tendency appeared in favor of arachnoidolysis for cyst evolution in regard to the extent of the cyst and the Vaquero index (P = .05). CONCLUSION: Our results confirmed that arachnoidolysis is an effective and safe treatment for posttraumatic syringomyelia. Because the majority of patients were stabilized, we concluded that surgery should be performed as soon as possible in patients with clearly progressing clinical features.

Results of microsurgical treatment of medulla oblongata and spinal cord hemangioblastomas: a comparison of two distinct clinical patient groups.

PURPOSE: To analyze the surgical outcome of a consecutive and single center series of medulla oblongata (MO) and spinal cord hemangioblastomas (HB). PATIENT AND METHODS: We retrospectively reviewed the medical charts of all MO and spinal HB patients operated on in our institution between 1985 and 2002. All patients had pre- and at least one post-operative MRI. McCormick classification was used to assess neurological status and functional outcome. RESULTS: Forty surgical procedures have been performed on 34 patients (19 females and 15 males, mean age of 41 years). Twenty-five (73%) patients had Von Hippel Lindau (VHL) disease confirmed by genetic screening, and nine patients had sporadic disease. Complete clinical, radiological, and genetic studies were done in all cases. The most frequent clinical symptom was pain (28 patient, 85%) followed by motor (42%) and sensitive deficits (42%). Fourteen lesions (19%) were located in the MO, 28 (38%) in the cervical spine, 25 (34%) in the thoracic spine, 4 (5%) in the lumbar spine and 3 (4%) in the Cauda Equina. In the VHL group, 15 patients (60%) presented multiple lesions and 10 a single neurological lesion (40%). A cyst was present in 23% of VHL patients and in 55% of the non-VHL group. A complete removal was achieved in 85% of all cases. No deaths related to surgery occurred. At the end of the follow-up period (mean 60 months) 50% of patients were stabilized, while the condition of 32.35% was improved and of 17.65% worsened. Comparing the clinical evolution considering the presence or not of VHL we have seen that there are no differences in terms of functional outcome between VHL and non-VHL groups. CONCLUSION: Our results confirmed that surgery remains a safe and effective treatment for medulla oblongata and spinal hemangioblastoma. Only symptomatic lesion required surgical treatment. In other cases, especially in VHL patients, a close and regular follow-up (clinical and MRI) is necessary.

Long-term follow-up of Chiari-related syringomyelia in adults: analysis of 157 surgically treated cases.

OBJECTIVE: To determine the long-term outcome of surgically treated Chiari-related syringomyelia. METHODS: The medical charts of 157 consecutive surgically treated patients with Chiari-related syringomyelia were retrospectively analyzed. Factors predicting outcome, either clinical or radiological, are discussed, and our results are compared with those of other large series in the literature. RESULTS: The study included 74 men and 83 women (age range, 16-75 years; mean age at surgery, 38.3 years). Pain and sensory disturbance were the most frequent initial symptoms. The average duration of preoperative symptoms was 8.2 years. The follow-up period ranged from 82 to 204 months (median, 88 months). At the end of the study, 99 patients (63.06%) had improved, 48 (30.58%) had stabilized, 9 (5.73%) had worsened, and 1 (0.63%) had died during the postoperative period. Factors predicting improvement or stabilization were young age at the time of surgery and clinical signs of paroxysmal intracranial hypertension. Factors associated with a poor outcome were older age at the time of surgery, arachnoiditis, and a clinical feature of long-tract impairment syndrome. The presence of arachnoiditis or of basilar invagination was associated with poor clinical presentation (P = 0.05 and 0.0001, respectively). The extent of the cyst on postoperative magnetic resonance imaging was a predictor of poor clinical outcome (P = 0.002). CONCLUSION: Our results confirmed that surgery is an effective and safe treatment of Chiari-related syringomyelia, with a 90% chance of long-term stabilization or improvement on average. Surgery should be proposed as soon as possible in patients with clearly progressing clinical features.

Decompressive craniectomy in children with nontraumatic refractory high intracranial pressure. Clinical article.

OBJECT: In this study, the authors investigated the clinical efficacy of decompressive craniectomy treatments for nontraumatic intracranial hypertension in children. METHODS: Seven patients with nontraumatic refractory high intracranial pressure (ICP) were enrolled in the study between 1995 and 2005; there were 2 boys and 5 girls with a mean age of 9 years (range 4-14). Decompressive craniectomy was performed in all patients after standard medical therapy had proven insufficient and ICP remained > 50 mm Hg. All patients had a Glasgow Coma Scale score < 8 at admission and a mean Pediatric Risk of Mortality Scale score of 20 (range 10-27). RESULTS: One patient died of persistent high ICP and circulatory failure 48 hours after surgery. Six months later, according to their Glasgow Outcome Scale scores, 3 patients had adequate recoveries, 2 patients recovered with moderate disabilities, and 1 patient had severe disabilities. According to the Pediatric Overall Performance Category Scale, 4 patients received a score of 2 (mild disability), 1 a score of 3 (moderate disability), and 1 a score of 4 (severe disability). Five patients returned to school and normal life. CONCLUSIONS: The authors found decompressive craniectomy to be an effective and lifesaving technique in children. This procedure should be included in the arsenal of treatments for nontraumatic intracranial hypertension.

Intramedullary spinal ependymomas: analysis of a consecutive series of 82 adult cases with particular attention to patients with no preoperative neurological deficit.

OBJECTIVE: Surgery should be considered for patients with intramedullary spinal ependymomas (ISE), particularly those presenting with a neurological deficit preoperatively. In contrast, it is still a debatable matter whether to recommend the same approach for patients with no neurological impairment. To investigate this matter, we analyzed the data of 82 consecutive patients with ISEs treated at our institution. METHODS: We reviewed the medical charts of all ISE patients undergoing operation at our institution between 1985 and 2000. Particular attention was given to patients without neurological deficit before surgery. RESULTS: Eighty-two consecutive ISE patients were included in this study. Preoperatively, a neurological deficit of variable severity was present in 72 patients (Group A, 88%) and absent in 10 patients (Group B, 12%). In the latter group, seven patients had progressive and nonspecific pain as the only presenting symptom; two had arm dysesthesias; and in one patient, ISE was diagnosed incidentally. The mean duration of their symptoms was 21 months. We achieved a total tumor excision in nine patients and subtotal removal in one. At the last follow-up assessment (mean, 45 mo), all Group B patients remained at Grade I of the McCormick classification, except one, who deteriorated to Grade Ib. Furthermore, nonspecific pain diminished in three patients, stabilized in four, and worsened in one. Arm dysesthesias diminished in one patient and stabilized in the other. No surgery-related complication or recurrence was recorded in these patients. CONCLUSION: Surgery should be carefully considered for ISE patients with no objective neurological deficit preoperatively because, in our experience, it resolves their preoperative complaints in 30% of cases, stabilizes them in 60%, and worsens them in 10%.

Curable cause of paraplegia: spinal dural arteriovenous fistulae.

BACKGROUND AND PURPOSE: The rarity of spinal dural arteriovenous fistulae makes physicians often overlook this potential diagnosis in patients with progressive gait disturbance and paraparesis. Consequently, patients with spinal dural arteriovenous fistulae can gradually become completely paraplegic if the final diagnosis is delayed considerably. The objective of the current study is to demonstrate that, particularly in patients with paraplegia, surgical treatment of fistula is necessary and often has a favorable outcome. METHODS: Of 42 patients with spinal dural arteriovenous fistulae treated in our institution (surgery or endovascular treatment), 6 were paraplegic preoperatively (Grade IV on the McCormick scale and Grade V on the Aminoff scale, Grade 5 of modified Rankin Scale with motor ASIA between 0 and 10 for both lower limbs). Their clinical history revealed that paraplegia appeared progressively within a period of <3 months. All patients were clinically evaluated at 6 weeks, 6 months, and then annually during an average follow-up of 3 years. Patients received at least one spinal angiography and MRI test during the follow-up period. RESULTS: Total exclusion of the fistula was performed surgically in all cases and was confirmed by spinal angiography. No surgical complications were recorded. All patients improved postoperatively. Three patients showed almost normal walking (Grade I on the McCormick scale, I on the Aminoff scale, Grade 1 of modified Rankin Scale) and 3 were able to walk with a cane (Grade II on McCormick, Grade III on Aminoff scale, Grade 2 of modified Rankin Scale). MRI tests were normal in all patients. CONCLUSIONS: Our results indicate that treatment of fistula is a necessary intervention, even in patients with complete paraplegia.

Multiple lumbar roots neurotizations with the lower intercostal nerves. Preliminary clinical and electrophysiological results in a sheep model.

INTRODUCTION: Neurotization of lumbar roots with lower intercostal nerves is a potential way to treat neurological deficits after spinal cord injury. The anatomical feasibility of such neurotizations in humans has already been reported. We propose to assess axonal regrowth after intercostal to lumbar neurotization in a sheep model. MATERIALS AND METHODS: Ten sheep had a left T11-L2, T12-L3, and T13-L4 neurotization. In 5 sheep, a L1 level left hemisection of the spinal cord was performed. The sheep had clinical and electrophysiological monitoring with a 6 mon follow-up. RESULTS: A flaccid paralysis with clinical asymmetry of the left abdominal wall was noted three months after surgery. This asymmetry improved in all the cases at the 6 mon follow-up. Motor potentials were detected without difficulty for the 3 neurotized nerves (L2, L3, and L4) in 5 sheep. In another sheep, motor potentials of the L3 root remained undetected. Eight sheep had postoperative complications responsible for the animals' death in 5 cases. CONCLUSIONS: The current study demonstrates the technical feasibility of intercosto-lumbar neurotizations in a sheep model. We proved in all the animals--except in the case of 1 neurotized root--the ability of motor axon to regenerate through neurotization area down to the muscular effectors; however, we noted a high rate of postoperative complications in this animal model.

The paraspinal splitting approach: a possible approach to perform multiple intercosto-lumbar neurotizations: an anatomic study.

STUDY DESIGN: Descriptive anatomy. OBJECTIVE.: To describe the anatomy associated with the extensive transmuscular paraspinal approach required to perform multiple intercosto-lumbar neurotizations. SUMMARY OF BACKGROUND DATA: Neurotization of lumbar roots using lower intercostal nerves is a potential method of treating neurologic deficits after spinal cord injury. It appeared to us that the paraspinal splitting approach was potentially an optimal method to perform intercostal nerve harvesting, rerouting, and intercosto-lumbar neurotizations. METHODS: Ninth, 10th, and 11th intercostal nerve harvesting and rerouting down to L2, L3, and L4 roots were performed on 50 cadavers. The descriptive anatomy and topographic landmarks are reported. RESULTS: The mean total length of intercostal nerve harvested was 17.96 (range, 10-27) cm for the 9th intercostal nerve, 17.14 cm (range, 10-20) for the 10th intercostal nerve and 15.94 cm (range, 10-25) for the 11th intercostal nerve. The length of harvested nerve was not correlated to the size of the trunk. The length of harvested nerve was sufficient to perform lumbar roots neurotizations in the 300 cases of nerve harvesting. CONCLUSION: Multiple lumbar roots neurotizations with lower intercostal nerves already have been proposed by other authors. In this strategy, the use of the spinal cord and intercostal nerves above the spinal cord lesion avoids the axonal regrowth required via the injured central nervous system. Rerouting intercostals nerves down to the lumbar roots at their exit from the intervertebral foraminae is less invasive that the same procedure performed down to the vertebral canal at the level of the cauda equina as we used in previous protocols. Our anatomic study confirms the advantage of the paraspinal sacrospinalis splitting approach in multiple intercosto-lumbar neurotizations. The approach is quick and easy and allows a good exposure of the nerve roots at the thoracic and lumbar levels. The L2, L3, and L4 roots could be satisfactorily neurotized with this procedure.

Pseudotumoral presentation of a cervical extracranial vertebral artery aneurysm in neurofibromatosis type 1: case report.

OBJECTIVE: Neurofibromatosis Type 1 (NF1) is known to be associated with vascular lesions. Association with an extracranial vertebral artery aneurysm is very rare. We report the case of such an aneurysm mimicking a cervical neurofibroma in NF1. CLINICAL PRESENTATION: An 18-year-old woman with previously diagnosed NF1 presented with a C6 radiculopathy. There were no clinical features suggesting a vascular origin for the lesion. The computed tomographic and standard magnetic resonance imaging scans showed a C5-C6 contrast-enhancing lesion responsible for bony erosion. Subsequent, magnetic resonance angiography and digital subtraction angiography diagnosed the lesion as a C5-C6 vertebral artery aneurysm. INTERVENTION: The lesion was treated by endovascular occlusion of both the aneurysm and the parent vertebral artery with an initial immediate disappearance of the pain. CONCLUSION: This case serves as a reminder of the importance of ruling out a vertebral artery aneurysm with angiography when managing cervical lesions in patients with NF1.

Diffusion tensor magnetic resonance imaging and fiber tracking in spinal cord lesions: current and future indications.

Diffusion-weighted imaging and fractional anisotropy may be more sensitive than other conventional magnetic resonance imaging techniques to detect, characterize, and map the extent of spinal cord lesions. Fiber tracking offers the possibility of visualizing the integrity of white matter tracts surrounding some lesions, and this information may help in formulating a differential diagnosis and in planning biopsies or resection. Fractional anisotropy measurements may also play a role in predicting the outcome of patients who have spinal cord lesions. In this article, we address several conditions in which diffusion-weighted imaging and fiber tracking is known to be useful and speculate on others in which we believe these techniques will be useful in the near future.

The feasibility of detecting motor and sensory potentials in a sheep model.

To investigate the characteristics of motor, sensory and sensory-evoked potentials (SEPs) of thoracic and lumbar roots, and demonstrate the feasibility of assessing axonal regrowth after the neurotization procedure in a sheep model. Six adult sheep were anaesthetized and placed in a sternal position. The thoracic and lumbar roots from T11 to L5 were identified at their emergence from the vertebral foramen and stimulated. Motor and sensory responses were monitored. Thoracic and lumbar roots were easily identified in all cases. Motor potentials were detected for each stimulated nerve without difficulty. The amplitudes were quite variable, ranging from 100 to 5300 microV. Sensory and SEPs were satisfactorily recorded in only three of the six animals. Sensory amplitudes also varied greatly, ranging from 25 to 120 microV. In three cases, SEPs could not be identified due to motor artefacts. The motor pathway after axonal regrowth in neurotized lumbar roots might easily be explored by proximal electric stimulation of the root, close to the sutured area. Detection of sensory and spinal cord evoked potentials might be improved by the use of curve summation techniques. Specific axonal tracing holds promise of being a useful technique for examining sensory and motor pathway recovery after neurotization in the sheep model.

Intraspinal grafting procedures: spinal cord effects induced in the adult rat: a clinical, histopathological, and immunohistochemical study.

OBJECTIVE: Intraspinal grafting procedures using peripheral nerve grafts (PNG) or collagen guidance channels (CGC) have been recently used to treat brachial plexus injuries in humans and spinal cord injuries in animals. This study examined the effects of these procedures in the adult rat. METHODS: In adult rats, we performed an avulsion of left C5, C6, and C7 nerve roots, followed by a myelotomy of the left ventrolateral aspect of the spinal cord between C5 and C6. The rats were subsequently assigned to one of three groups: group A (n = 10), no additional procedure; group B (n = 10), implantation of a PNG following myelotomy; group C (n = 10), implantation of a CGC. Clinical evaluation was postoperatively assessed. Rats were euthanized at day 6 or 21. Spinal cord lesions induced by surgery were assessed by measuring depth and rostrocaudal extent. Reactive astrogliosis, as a reaction to neuroglial damage, was assessed by revealing the glial fibrillary acidic protein with immunochemistry method. RESULTS: No animal showed persistent neurological deficit at day 21. The depth and rostrocaudal extent of tissue damage was comparable in all groups at days 6 and 21. At day 6, the astrocytic reaction observed at the myelotomy/implantation site was statistically stronger in group C (CGC). At day 21, the astrocytic reaction became identical in all groups. CONCLUSION: This study shows that grafting a PNG or a CGC into the spinal cord does not create significant additional iatrogenic effects and can be used in repair strategies to treat nerve root avulsions or spinal cord injuries.

Anatomical feasibility of using the ninth, 10th, and 11th intercostal nerves for the treatment of neurological deficits after damage to the spinal cord.

OBJECT: The topographic anatomy of the lower intercostal nerves is less well known than that of the upper ones, except for the 12th intercostal nerve. It is possible to use the lower intercostal nerves to perform a neurotization of the lumbar roots. The authors studied the anatomy of the ninth, 10th, and 11th intercostal nerves to obtain descriptive and topographic anatomical data to aid in establishing optimal conditions for harvesting. METHODS: The ninth, 10th, and 11th intercostal nerves of 50 cadavers were dissected. The proximal part of the nerve in the posterior intercostal space (ISC) was exposed through a posterior approach. The lateral ICS was exposed through a lateral approach, under the latissimus dorsi, which made it possible to harvest the intercostal nerves using a stripping technique. A histological study was conducted on 10 pigs to evaluate the risk of nerve lesions during the stripping procedure. CONCLUSIONS: The proximal course of the nerve in the posterior ICS was the same in all cases. The mean total length of the intercostal nerves harvested was 17.96 cm for the ninth, 17.14 cm for the 10th, and 15.94 cm for the 11th intercostal nerve. The harvested nerve length was sufficient in 297 of the 300 cases to perform lumbar root neurotization. The histological study showed no difference between the "open" and the "stripping" techniques regarding the risk of histological lesions in harvested nerves.

Spinal cord intradural arteriovenous fistulae: anatomic, clinical, and therapeutic considerations in a series of 32 consecutive patients seen between 1981 and 2000 with emphasis on endovascular therapy.

OBJECTIVE: To review our series of intradural spinal cord arteriovenous fistulas (SCAVFs), analyzing symptoms and related angioarchitecture, and to study the morphological and clinical results of embolization. METHODS: Thirty-two SCAVFs (in 22 adults and 10 children) were treated between 1981 and 2000. These lesions were classified as microarteriovenous fistulas (mAVFs) or macroarteriovenous fistulas (MAVFs) according to shunt morphology. Location, architecture, presenting symptoms, and age group were detailed. The selection of patients for endovascular versus surgical treatments was analyzed, as were the anatomic and clinical results obtained by embolization with n-butylcyanoacrylate. Clinical status was evaluated according to the Karnofsky Performance Scale score. RESULTS: Ten SCAVFs were found in the pediatric population (four mAVFs and six MAVFs). All four mAVFs presented with acute symptoms. Three mAVFs (two cervical and one thoracic) presented hematomyelia; in one patient with a thoracic AVF, subarachnoid hemorrhage was suspected. All six MAVFs were located in the thoracolumbar cord (five associated with hereditary hemorrhagic telangiectasias). Four of the six MAVFs presented with hemorrhage. In the adult population, there were 21 mAVFS (95%) and one MAVF (5%). Only two mAVFs were found in the cervical cord, all other shunts affecting the thoracolumbar region. Hemorrhage was present in 6 of the 22 cases seen in adults (27%). The symptoms of SCAVFs did not differ from those found in spinal cord arteriovenous shunts of nidus type. Pial venous reflux and congestion were the most frequently encountered features in both the adult and pediatric groups. Arterial aneurysms (different from false aneurysms) were not found in association with hemorrhagic presentation of SCAVFs. Mean follow-up in our series was 3.3 years. Of the MAVFs, 86% were embolized, with 67% cured. The others had more than 75% occlusion. All patients followed up improved significantly. Of the mAVFs, 48% were treated endovascularly. Successful embolization was performed in 75% of patients. One patient was not embolized because of vasospasm, whereas 67% percent of mAVFs were completely occluded, 22% were more than 90% occluded, and 11% were 75% occluded. Complementary surgery was deemed unnecessary. All patients with mAVFs improved significantly at follow-up. Transient complications occurred in 22% of all patients, with no permanent morbidity or mortality. No patient bled or rebled after embolization. Thirty-six percent of mAVFs were operated on because of anticipated technical difficulties for endovascular approach or distal localization of the shunt. CONCLUSION: Endovascular treatment of SCAVFs stabilizes, normalizes, or improves neurological symptoms in all patients at long-term follow-up, with no bleeds or rebleeds. Embolization of SCAVFs with glue is a safe treatment that compares favorably with other approaches and significantly improves the poor natural history of the disease.

Late paraplegia after scoliosis treatment: an uncommon diagnosis.

We report the case of a young girl treated at age 16 for a progressive scoliosis by posterior instrumented arthrodesis. Ten years later, she suddenly developed lumbar pain and paraplegia. The surgical procedure showed a mass infiltrating the vertebral canal and the dural sheath following a supralaminar hook. Histology revealed a diagnosis of leiomyosarcoma. The outcome was poor with a rapid and fatal extension of the tumor. There is nothing to justify a causal link between the scoliosis and the late onset of a malignant tumor. Nevertheless, we discuss the potential role of diagnostic irradiation consecutive to scoliosis monitoring during growth and the potential role of environmental carcinogens like metallic biomaterials. Finally, rapid intrusion of this extraspinal tumor into the dural sheath resulted in a confusing clinical picture and delayed the diagnosis and treatment of the tumor.

Reinnervation of hind limb extremity after lumbar dorsal root ganglion injury.

Loss of dorsal root ganglion neuron, or injury to dorsal roots, induces permanent somatosensory defect without therapeutic option. We explored an approach to restoring hind limb somatosensory innervation after elimination of L4, L5 and L6 dorsal root ganglion neurons in rats. Somatosensory pathways were reconstructed by connecting L4, L5 and L6 lumbar dorsal roots to T10, T11 and T12 intercostal nerves, respectively, thus allowing elongation of thoracic ganglion neuron peripheral axons into the sciatic nerve. Connection of thoracic dorsal root ganglion neurons to peripheral tissues was documented 4 and 7 months after injury. Myelinated and unmyelinated fibers regrew in the sciatic nerve. Nerve terminations expressing calcitonin-gene-related-peptide colonized the footpad skin. Retrograde tracing showed that T10, T11 and T12 dorsal root ganglion neurons expressing calcitonin-gene-related-peptide or the neurofilament RT97 projected axons to the sciatic nerve and the footpad skin. Recording of somatosensory evoked potentials in the upper spinal cord indicated connection between the sciatic nerve and the central nervous system. Hind limb retraction in response to nociceptive stimulation of the reinnervated footpads and reversion of skin lesions suggested partial recovery of sensory function. Proprioceptive defects persisted. Delayed somatosensory reinnervation of the hind limb after destruction of lumbar dorsal root neurons in rats indicates potential approaches to reduce chronic disability after severe injury to somatosensory pathways.

Reduction of postoperative perineural adhesions by Hyaloglide gel: an experimental study in the rat sciatic nerve.

OBJECTIVE: To assess the effects of Hyaloglide gel (or auto-cross-linked polysaccharide [ACP] gel; Fidia Advanced Biopolymers, Abano Terme, Italy), a hyaluronan-derivative polymer, on peripheral nerve scarring and nerve regeneration. METHODS: We performed two surgical procedures in adult rats: 1) neurolysis of the sciatic nerve and separation of its tibial and peroneal branches, and 2) transection and immediate suture of the sciatic nerve. After nerve manipulation, ACP gel was applied onto the site of operation. We tested two solutions of ACP gel having different viscosities. Additional animals received Adcon-T/N (Gliatech, Inc., Cleveland, OH), an antiadhesive agent currently available for clinical use. No gel was applied on the contralateral side, which served as a control side. Four weeks later, the animals underwent reoperation. We assessed the quality of wound healing, the presence of perineural adherences, and the separability of nerves from surrounding tissues. RESULTS: Significantly fewer perineural adhesions were found in animals treated with ACP gel (high viscosity) and Adcon-T/N compared with controls. Quantitative histological analysis revealed a statistically significant reduction in the amount of scar tissue surrounding the nerves treated with ACP gel. No evidence of toxicity was found, and the gel did not interfere with nerve regeneration (counts of regenerating myelinated axons). CONCLUSION: ACP gel with high viscosity seems to be safe and effective in reducing perineural adhesions and scar formation after peripheral nerve surgery.