How Should we Use Multicolumn Spinal Cord Stimulation to Optimize Back Pain Spatial Neural Targeting? A Prospective, Multicenter, Randomized, Double-Blind, Controlled Trial (ESTIMET Study).

BACKGROUND: Recent studies have highlighted multicolumn spinal cord stimulation (SCS) efficacy, hypothesizing that optimized spatial neural targeting provided by new-generation SCS lead design or its multicolumn programming abilities could represent an opportunity to better address chronic back pain (BP). OBJECTIVE: To compare multicolumn vs. monocolumn programming on clinical outcomes of refractory postoperative chronic BP patients implanted with SCS using multicolumn surgical lead. MATERIALS AND METHODS: Twelve centers included 115 patients in a multicenter, randomized, double-blind, controlled trial. After randomization, leads were programmed using only one or several columns. The primary outcome was change in BP visual analogic scale (VAS) at six months. All patients were then programmed using the full potential of the lead up until 12-months follow-up. RESULTS: At six months, there was no significant difference in clinical outcomes whether the SCS was programmed using a mono or a multicolumn program. At 12 months, in all patients having been receiving multicolumn SCS for at least six months (n = 97), VAS decreases were significant for global pain (45.1%), leg pain (55.8%), and BP (41.5%) compared with baseline (p < 0.0001). CONCLUSION: The ESTIMET study confirms the significant benefit experienced on chronic BP by patients implanted with multicolumn SCS, independently from multicolumn lead programming. These good clinical outcomes might result from the specific architecture of the multicolumn lead, giving the opportunity to select initially the best column on a multicolumn grid and to optimize neural targeting with low-energy requirements. However, involving more columns than one does not appear necessary, once initial spatial targeting of the "sweet spot" has been achieved. Our findings suggest that this spatial concept could also be transposed to cylindrical leads, which have drastically improved their capability to shape the electrical field, and might be combined with temporal resolution using SCS new modalities.

Prognostic factors for survival in adult patients with recurrent glioblastoma: a decision-tree-based model.

We assessed prognostic factors in relation to OS from progression in recurrent glioblastomas. Retrospective multicentric study enrolling 407 (training set) and 370 (external validation set) adult patients with a recurrent supratentorial glioblastoma treated by surgical resection and standard combined chemoradiotherapy as first-line treatment. Four complementary multivariate prognostic models were evaluated: Cox proportional hazards regression modeling, single-tree recursive partitioning, random survival forest, conditional random forest. Median overall survival from progression was 7.6 months (mean, 10.1; range, 0-86) and 8.0 months (mean, 8.5; range, 0-56) in the training and validation sets, respectively (p = 0.900). Using the Cox model in the training set, independent predictors of poorer overall survival from progression included increasing age at histopathological diagnosis (aHR, 1.47; 95% CI [1.03-2.08]; p = 0.032), RTOG-RPA V-VI classes (aHR, 1.38; 95% CI [1.11-1.73]; p = 0.004), decreasing KPS at progression (aHR, 3.46; 95% CI [2.10-5.72]; p < 0.001), while independent predictors of longer overall survival from progression included surgical resection (aHR, 0.57; 95% CI [0.44-0.73]; p < 0.001) and chemotherapy (aHR, 0.41; 95% CI [0.31-0.55]; p < 0.001). Single-tree recursive partitioning identified KPS at progression, surgical resection at progression, chemotherapy at progression, and RTOG-RPA class at histopathological diagnosis, as main survival predictors in the training set, yielding four risk categories highly predictive of overall survival from progression both in training (p < 0.0001) and validation (p < 0.0001) sets. Both random forest approaches identified KPS at progression as the most important survival predictor. Age, KPS at progression, RTOG-RPA classes, surgical resection at progression and chemotherapy at progression are prognostic for survival in recurrent glioblastomas and should inform the treatment decisions.

Recurrent glioblastomas in the elderly after maximal first-line treatment: does preserved overall condition warrant a maximal second-line treatment?

A growing literature supports maximal safe resection followed by standard combined chemoradiotherapy (i.e. maximal first-line therapy) for selected elderly glioblastoma patients. To assess the prognostic factors from recurrence in elderly glioblastoma patients treated by maximal safe resection followed by standard combined chemoradiotherapy as first-line therapy. Multicentric retrospective analysis comparing the prognosis and optimal oncological management of recurrent glioblastomas between 660 adult patients aged of < 70 years (standard group) and 117 patients aged of ≥70 years (elderly group) harboring a supratentorial glioblastoma treated by maximal first-line therapy. From recurrence, both groups did not significantly differ regarding Karnofsky performance status (KPS) (p = 0.482). Oncological treatments from recurrence significantly differed: patients of the elderly group received less frequently oncological treatment from recurrence (p < 0.001), including surgical resection (p < 0.001), Bevacizumab therapy (p < 0.001), and second line chemotherapy other than Temozolomide (p < 0.001). In multivariate analysis, Age ≥70 years was not an independent predictor of overall survival from recurrence (p = 0.602), RTOG-RPA classes 5-6 (p = 0.050) and KPS at recurrence <70 (p < 0.001), available in all cases, were independent significant predictors of shorter overall survival from recurrence. Initial removal of ≥ 90% of enhancing tumor (p = 0.004), initial completion of the standard combined chemoradiotherapy (p = 0.007), oncological treatment from recurrence (p < 0.001), and particularly surgical resection (p < 0.001), Temozolomide (p = 0.046), and Bevacizumab therapy (p = 0.041) were all significant independent predictors of longer overall survival from recurrence. Elderly patients had substandard care from recurrence whereas age did not impact overall survival from recurrence contrary to KPS at recurrence <70. Treatment options from recurrence should include repeat surgery, second line chemotherapy and anti-angiogenic agents.

Natural course and prognosis of anaplastic gangliogliomas: a multicenter retrospective study of 43 cases from the French Brain Tumor Database.

Background: Anaplastic gangliogliomas (GGGs) are rare tumors whose natural history is poorly documented. We aimed to define their clinical and imaging features and to identify prognostic factors. Methods: Consecutive cases of anaplastic GGGs in adults prospectively entered into the French Brain Tumor Database between March 2004 and April 2014 were screened. After diagnosis was confirmed by pathological review, clinical, imaging, therapeutic, and outcome data were collected retrospectively. Results: Forty-three patients with anaplastic GGG (median age, 49.4 y) from 18 centers were included. Presenting symptoms were neurological deficit (37.2%), epileptic seizure (37.2%), or increased intracranial pressure (25.6%). Typical imaging findings were unifocal location (94.7%), contrast enhancement (88.1%), central necrosis (43.2%), and mass effect (47.6%). Therapeutic strategy included surgical resection (95.3%), adjuvant radiochemotherapy (48.8%), or radiotherapy alone (27.9%). Median progression-free survival (PFS) and overall survival (OS) were 8.0 and 24.7 months, respectively. Three- and 5-year tumor recurrence rates were 69% and 100%, respectively. The 5-year survival rate was 24.9%. Considering unadjusted significant prognostic factors, tumor midline crossing and frontal location were associated with shorter OS. Temporal and parietal locations were associated with longer and shorter PFS, respectively. None of these factors remained statistically significant in multivariate analysis. Conclusions: We report a large series providing clinical, imaging, therapeutic, and prognostic features of adult patients treated for an intracerebral anaplastic GGG. Our results show that pathological diagnosis is difficult, that survivals are only slightly better than for glioblastomas, and that complete surgical resection followed with adjuvant chemoradiotherapy offers longer survival.

Chronic subdural haematomas in elderly population. Neurosurgical aspects and focus on the single-burr hole technique performed under assisted local anaesthesia.

OBJECTIVE: Chronic subdural haematomas (CSDH) is a common pathology that usually affects the elderly population. The incidence of CSDH has recently been increasing with the expansion of the aging population. The objective of our study was to evaluate the outcome following surgical drainage of CSDH in elderly patients. MATERIALS AND METHODS: We performed a retrospective analysis of 455 consecutive patients with CSDHs over a 5-year period. Among them, all 121 patients older than 80-year old were included in the study. Clinical status, comorbidities, type of surgical technique and outcome were analyzed. Outcome at last follow-up was measured using the Markwalder grading score and the Glasgow outcome scale. RESULTS: Patients ranged from 80- to 94-year old with a median age of 84 years (range 80-94). Ninety-eight percent of patients were surgically treated by a small burr hole under assisted local anaesthesia. About 69.2% of patients improved post-operatively. The mortality rate was 6.8%. CONCLUSION: CSDH is a common pathology in the elderly population. Patients with CSDHs often have comorbodities that need to be considered in deciding whether surgical treatment is indicated. When surgery is elected, small craniostomy techniques performed under assisted local anesthesia is safe and should be favored in this frail population.

Delaying standard combined chemoradiotherapy after surgical resection does not impact survival in newly diagnosed glioblastoma patients.

BACKGROUND: To assess the influence of the time interval between surgical resection and standard combined chemoradiotherapy on survival in newly diagnosed and homogeneously treated (surgical resection plus standard combined chemoradiotherapy) glioblastoma patients; while controlling confounding factors (extent of resection, carmustine wafer implantation, functional status, neurological deficit, and postoperative complications). METHODS: From 2005 to 2011, 692 adult patients (434 men; mean of 57.5 ± 10.8 years) with a newly diagnosed glioblastoma were enrolled in this retrospective multicentric study. All patients were treated by surgical resection (65.5% total/subtotal resection, 34.5% partial resection; 36.7% carmustine wafer implantation) followed by standard combined chemoradiotherapy (radiotherapy at a median dose of 60 Gy, with daily concomitant and adjuvant temozolomide). Time interval to standard combined chemoradiotherapy was analyzed as a continuous variable and as a dichotomized variable using median and quartiles thresholds. Multivariate analyses using Cox modeling were conducted. RESULTS: The median progression-free survival was 10.3 months (95% CI, 10.0-11.0). The median overall survival was 19.7 months (95% CI, 18.5-21.0). The median time to initiation of combined chemoradiotherapy was 1.5 months (25% quartile, 1.0; 75% quartile, 2.2; range, 0.1-9.0). On univariate and multivariate analyses, OS and PFS were not significantly influenced by time intervals to adjuvant treatments. On multivariate analysis, female gender, total/subtotal resection and RTOG-RPA classes 3 and 4 were significant independent predictors of improved OS. CONCLUSIONS: Delaying standard combined chemoradiotherapy following surgical resection of newly diagnosed glioblastoma in adult patients does not impact survival.

Allelic loss of 9p21.3 is a prognostic factor in 1p/19q codeleted anaplastic gliomas.

OBJECTIVES: We aimed to study the potential clinical relevance of 9p allelic loss, with or without copy number variation, in 1p/19q codeleted anaplastic oligodendroglial tumors (AOTs). METHODS: This study enrolled 216 patients with 1p/19q codeleted AOT. The prognostic value of 9p allelic loss was investigated using a French nation-wide prospective registry, POLA (prise en charge des tumeurs oligodendrogliales anaplasiques) and high-density single nucleotide polymorphism arrays. We validated our results using the Repository of Molecular Brain Neoplasia Data (REMBRANDT) dataset. RESULTS: The minimal common region of allelic loss in chromosome arm 9p was 9p21.3. Allelic loss of 9p21.3, detected in 41.7% of tumors, was associated with shorter progression-free and overall survival rates in univariate (p = 0.008 and p < 0.001, respectively) and multivariate analyses (p = 0.009 and p = 0.009, respectively). This finding was validated in the REMBRANDT dataset in univariate and multivariate analysis (p = 0.01 and p = 0.01, respectively). CONCLUSION: Our study highlights a novel potential prognostic biomarker in 1p/19q codeleted AOT. Further prospective studies are warranted to investigate our finding.

Venous organization in the transverse foramen: dissection, histology, and magnetic resonance imaging.

OBJECT: The anatomical arrangement of the venous system within the transverse foramen is controversial; there is disagreement whether the anatomy consists of a single vertebral vein or a confluence of venous plexus. Precise knowledge of this arrangement is necessary in imaging when vertebral artery dissection is suspected, as well as in surgical approaches for the cervical spine. This study aimed to better explain anatomical organization of the venous system within the transverse foramen according to the Trolard hypothesis of a transverse vertebral sinus. METHODS: This was an anatomical and radiological study. For the anatomical study, 10 specimens were analyzed after vascular injection. After dissection, histological cuts were prepared. For the radiological study, a high-resolution MRI study with 2D time-of-flight segment MR venography sequences was performed on 10 healthy volunteers. RESULTS: Vertebral veins are arranged in a plexiform manner within the transverse canal. This arrangement begins at the upper part of the transverse canal before the vertebral vein turns into a single vein along with the vertebral artery running from the transverse foramen of the C-6. This venous system runs somewhat ventrolaterally to the vertebral artery. In most cases, this arrangement is symmetrical and facilitates radiological readings. The anastomoses between vertebral veins and ventral longitudinal veins are uniform and arranged segmentally at each vertebra. CONCLUSIONS: These findings confirm recent or previous anatomical descriptions and invalidate others. It is hard to come up with a common description of the arrangement of vertebral veins. The authors suggest providing clinicians as well as anatomists with a well-detailed description of components essential to the understanding of this organization.

SNP array analysis reveals novel genomic abnormalities including copy neutral loss of heterozygosity in anaplastic oligodendrogliomas.

Anaplastic oligodendrogliomas (AOD) are rare glial tumors in adults with relative homogeneous clinical, radiological and histological features at the time of diagnosis but dramatically various clinical courses. Studies have identified several molecular abnormalities with clinical or biological relevance to AOD (e.g. t(1;19)(q10;p10), IDH1, IDH2, CIC and FUBP1 mutations).To better characterize the clinical and biological behavior of this tumor type, the creation of a national multicentric network, named "Prise en charge des OLigodendrogliomes Anaplasiques (POLA)," has been supported by the Institut National du Cancer (InCA). Newly diagnosed and centrally validated AOD patients and their related biological material (tumor and blood samples) were prospectively included in the POLA clinical database and tissue bank, respectively.At the molecular level, we have conducted a high-resolution single nucleotide polymorphism array analysis, which included 83 patients. Despite a careful central pathological review, AOD have been found to exhibit heterogeneous genomic features. A total of 82% of the tumors exhibited a 1p/19q-co-deletion, while 18% harbor a distinct chromosome pattern. Novel focal abnormalities, including homozygously deleted, amplified and disrupted regions, have been identified. Recurring copy neutral losses of heterozygosity (CNLOH) inducing the modulation of gene expression have also been discovered. CNLOH in the CDKN2A locus was associated with protein silencing in 1/3 of the cases. In addition, FUBP1 homozygous deletion was detected in one case suggesting a putative tumor suppressor role of FUBP1 in AOD.Our study showed that the genomic and pathological analyses of AOD are synergistic in detecting relevant clinical and biological subgroups of AOD.

Bilateral subdural hematoma following implantation of intrathecal drug delivery device.

OBJECTIVES: To report a case of bilateral subacute subdural hematoma following implantation of intrathecal drug delivery device. MATERIALS AND METHODS: We present here the case of a 41-year-old woman with multiple sclerosis and intractable spasticity who developed a bilateral subacute subdural hematoma after the placement of an intrathecal catheter connected to a programmable pump for baclofen infusion. RESULTS: Surgical drainage of the hematoma resulted in full neurologic recovery. This complication due to intracranial hypotension following lumbar puncture has been previously reported only once in patients with implanted intrathecal drug delivery device. CONCLUSIONS: Medical and nursing staff dealing with intrathecal therapy should be aware of this potentially severe complication.

Recovery after tetraplegia caused by dermal sinus infection: intramedullary abscess and tetraparesis.

Congenital dermal sinuses result from abnormal neurulation, and are uncommon. A spinal intramedullary abscess secondary to an infected dermoid cyst is very rare, and the functional prognosis is usually quite poor. We report on a 16-month-old child with tetraplegia secondary to intramedullary abscesses because of a dermoid cyst infection associated with a dermal sinus. The abscesses were drained, and the dermoid cyst was removed. Antibiotics were administered for 6 weeks after neurosurgery. The child was followed at a pediatric rehabilitation department. After 1 year, he was able to walk quickly and had regained appropriate upper limb motor function for his age. However, bladder sphincter dyssynergia persisted, requiring intermittent catheterization. This case highlights the importance of early diagnosis for surgical intervention and prolonged antibiotic therapy. Long-term follow-up by a multidisciplinary team allowed for the effective management of related neurologic, orthopedic, and bladder disorders.

Cervical cord compression due to delayed scarring around epidural electrodes used in spinal cord stimulation.

The authors report on 2 cases of delayed compression of the cervical spinal cord by dense scar tissue forming around epidural electrodes implanted for spinal cord stimulation (SCS). This complication has not been previously reported. Myelopathy developed in 2 patients 5 and 16 years after the surgical placement of a cervical epidural electrode. Prior to myelopathy, both patients experienced a tolerance phenomenon. Magnetic resonance imaging in both cases showed severe compression of the spinal cord by the electrode. At surgery, thick scar tissue surrounding the electrode and compressing the posterior aspect of the cord was discovered. Both patients experienced a full recovery following the removal of both scar tissue and the electrode. Medical and paramedical staff dealing with SCS should be aware of this severe and delayed complication. In addition, the development of epidural fibrosis can explain the occurrence of tolerance.

Retrospective study of 19 patients with intramedullary spinal cord metastasis.

OBJECT: Intramedullary spinal cord metastasis (ISCM) is a rare but devastating complication of cancer. Due to both widespread MRI availability and longer survival of cancer patients, the probability of discovering an ISCM during the course of the disease has increased and raised issues regarding the management of these patients, and particularly the place of surgery. In this study, we assess predictive factors for surgical outcome and survival. PATIENTS AND METHODS: We retrospectively reviewed a series of 19 patients consecutively admitted in our institution from 1993 to 2006 for ISCM, representing the second largest series published in the literature. MRI was performed on all patients. Thirteen underwent microsurgical excision of ISCM. Functional outcome was evaluated and factors influencing survival were statistically analyzed. RESULTS: Median survival was statistically longer when surgery was performed (7.4 vs. 2.6 months). Preoperative neurological status, nature of primary cancer, presence of systemic and/or CNS metastases influenced survival, but differences were without statistical significance. Neurological status improved in 58% (11/19) of operated patients. CONCLUSIONS: Optimal management of patients with ISCM is difficult due to the wide variety of clinical situations and the lack of controlled studies on the results of different therapeutic options. Diagnosis should be made as early as possible and surgical resection should be considered as the primary treatment whenever feasible, particularly in the case of rapidly progressive neurological deficits and when a clear cleavage plane exists. Our study shows that surgery could result in both increased survival rate and significant improvement of neurological function.

Low HER2-expressing glioblastomas are more often secondary to anaplastic transformation of low-grade glioma.

BACKGROUND: Anti-Human Epithelial Receptor Type 2 (HER2) antibodies have the ability to induce in vitro apoptosis of glioblastoma (GBM) cells. This study was designed to evaluate the variability of HER2 expression in GBM and its role as a possible prognosis factor. METHODS: Data of 57 patients with GBM and 16 patients with grade III gliomas were retrospectively analyzed. The expression of HER2 was determined by immunohistochemistry and intensity was noted from 0+ to 3+. We compared the HER2 expression in de novo GBM and in GBM resulting from anaplastic transformation of low-grade glioma ("secondary GBM"). Statistical analysis was performed using univariate analysis and the Kaplan-Meier method. FINDINGS: All GBM expressing highly HER2 (2+ and 3+) were de novo GBM. All secondary GBM expressed HER2 with low intensity (0+ and 1+). Survival time was significantly longer when HER2 expression was low (Log Rank test P = 0.04). The patterns of HER2 expression were similar between grade III gliomas and secondary GBM. CONCLUSIONS: To our best knowledge, our study showed for the first time a significant association between HER2 expression and the type of GBM, with subsequent influence on survival rate. GBM with low-HER2 expression are more likely to be secondary GBM, carrying a better prognosis than de novo GBM.

Management of ACTH-secreting supradiaphragmatic adenomas.

Supradiaphragmatic adrenocorticotropic hormone (ACTH) secreting pituitary adenomas are exceptionally encountered (14 cases previously described) and raise issues concerning their nosology and management. If surgery is the treatment of choice, the nature of surgical approach (craniotomy, transsphenoidal approach) remains controversial. To illustrate this issue, we presented two cases of supradiaphragmatic ACTH secreting pituitary adenomas successfully excised via a subfrontal approach. Both patients were female (20 and 41 years) and had a typical Cushing's syndrome. MRI revealed, in both cases, a suprasellar mass in contact with the pars tuberalis of the pituitary. In the first case, the patient underwent initially a transsphenoidal approach with negative exploration and subsequent partial hypophysectomy. One year later, the patient was operated on again via a subfrontal approach, allowing excision of a supradiaphragmatic adenoma and a complete cure of Cushing's disease. In the second case, the patient underwent initially a subfrontal approach and was definitely cured. In both cases, the diaphragma sellae was found to be intact and the pituitary stalk could be preserved. Postoperative MRI demonstrated a clearly visible intact pituitary stalk in conjunction with normal aspect of the pituitary. Supradiaphragmatic pituitary adenomas are most likely adenomas of the pituitary stalk with extra-axial development. Surgery remains the treatment of choice. Should the superior approach be preferred, the transsphenoidal-transtuberculum sellae approach may represent a viable alternative when performed by a well-trained surgical team. Surgery may be difficult, and drawbacks are non negligible, particularly in elderly patients. In these cases, stereotactic radiosurgery should receive more consideration.

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.

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.

Computed tomography images of entrapped epidural catheter.

OBJECTIVE: Knotting and looping of catheters in the epidural space occur rarely. Visualization of a catheter by radiograph or fluoroscopy is not always possible and often inaccurate in locating the knot and/or the loop with precision. We report the case of an entrapped lumbar epidural catheter. Computed tomography (CT) clearly showed a knotted and looped catheter. CASE REPORT: A 27-year-old woman underwent epidural analgesia during labor. The epidural catheter was inserted 7 cm into the epidural space. After unsuccessful attempts at removing the catheter, a CT scan was performed, and it showed a catheter knot in the epidural space as well as a loop within the interlaminar ligamentum flavum between L3 and L4. This explained why attempts to remove the catheter by manual traction failed. Surgical removal of the catheter was subsequently performed. CONCLUSIONS: CT is useful in showing an entrapped epidural catheter and the mechanisms of entrapment. Surgery should be considered when gentle traction fails to retrieve the catheter. CT allows the clinician to localize the catheter with accuracy, thus facilitating surgical follow-up.

Regeneration of primary sensory axons into the adult rat spinal cord via a peripheral nerve graft bridging the lumbar dorsal roots to the dorsal column.

This study investigated the feasibility of using a peripheral nerve autograft (NAG) to promote and guide regeneration of sensory axons from the caudal lumbar dorsal roots to the rostral dorsal column following a lower thoracic cordotomy in adult rats. After a left hemicordotomy at the T13 vertebra level and ipsilateral L3 and L4 rhizotomies, a peripheral NAG (peroneal nerve) was connected to the distal roots stumps, then implanted into the left dorsal column 10 mm rostral to hemicordotomy site (n = 12). After surgery, all animals of the experimental group experienced complete anesthesia in their left hindlimb. Three months later, a slight response to nociceptive stimulation reappeared in L3 and/or L4 dermatomes in 6 of the 12 experimental animals. None of these animals exhibited self-mutilation. Nine months after surgery, we performed retrograde tracing studies by injecting horseradish peroxidase (HRP) into the left dorsal column 30 mm rostral to the NAG implantation site. In eight animals, we found HRP-stained neurons in the left L3 and/or L4 dorsal root ganglia (DRG). The mean number of HRP-stained neurons per DRG was 71 +/- 92 (range 2-259). In control groups, no HRP-stained neurons were found in L3 or L4 DRG. Histological analysis of the NAG showed evidence of axonal regeneration in all 8 animals with positive retrograde labeling of DRG neurons. However, we did not find a statistical correlation between the number of HRP-stained neurons and the degree of sensory recovery. This study demonstrates that an NAG joining dorsal roots to the dorsal column, thus shunting the original CNS-PNS junction, can support regeneration of central axons from DRG primary sensory neurons into the dorsal column over distances of at least 30 mm despite the inhibitory influence of the CNS white matter.