Motor and sensitive axonal regrowth after multiple intercosto-lumbar neurotizations in a sheep model.

STUDY DESIGN: Experimental animal study. OBJECTIVE: To evaluate motor and sensitive axonal regrowth after multiple intercosto-lumbar neurotizations in a sheep model. SETTING: France. METHODS: Fifteen sheep were separated into three groups. Five sheep had multiple intercosto-lumbar neurotizations and a spinal cord lesion, five sheep were neurotized without any spinal cord lesion and five sheep had a spinal cord lesion without any neurotizations. Six months after the initial surgery, histological study of the neurotized roots was performed. RESULTS: The length of the three rerouted intercostal nerves was sufficient in the 10 sheep to perform an intercosto-lumbar neurotization in good conditions. Eight sheep out of the 15 had postoperative complications responsible for the animal's death in five cases. Histological cross-sections of all the neurotized L2, L3 and L4 roots showed numerous myelinated regenerated axons. Dorsal root ganglions of neurotized roots showed both large and small neurons with normal nucleus and cytoplasm. The fluorescent retrograde labeling of 18 roots revealed labeled motor neurons in five cases. CONCLUSIONS: This study demonstrates the technical feasibility of intercosto-lumbar neurotizations in a big mammalian model. Intercostal nerve harvesting and rerouting was successfully performed in all the cases. Our histological results proved, in all the animals studied, the ability of motor and sensitive neurons to regenerate through the neurotization area. In the context of the future clinical application of strategies aimed at promoting axonal regeneration after severe spinal cord injury, the present data suggest that multiple intercosto-lumbar neurotization could be helpful to promote lower limb muscular strength recovery after spinal cord injuries.

[Craniocerebral gunshot wounds: a study of outcome predictors]. / Les plaies crâniocérébrales d'origine balistique: recherche d'arguments pronostiques.

BACKGROUND AND PURPOSE: A retrospective study about craniocerebral gunshot wounds was done to better identify outcome predictors. METHODS: We reported and analyzed the clinical and radiological data of 18 patients admitted to Le Kremlin-Bicêtre institute for a craniocerebral gunshot wound between January 2000 and December 2005. The Glasgow Outcome Scale (GOS) was used to analyze patient outcome. RESULTS: There were 17 men and one woman, mean age 43 years (range 17-84). Fifteen patients died, two had a GOS equal to 2 and one GOS equal to 3. There were 16 suicides and two murders. All patients with areactive bilateral mydriasis and all patients with Glasgow Coma Scale (GCS) less than seven died except one. The 10 patients with intraventricular hemorrhage died. The bullet crossed the midline for 13 patients and all of them died. None of the patients underwent emergency surgery for the treatment of craniocerebral gunshot wounds because of low Glasgow Coma Scale. CONCLUSIONS: This study shows some interesting prognosis patterns: bilateral areactive mydriasis, GCS less or equal to 7 and bullet trajectory (if crossing the midline) are the most important factors predicting a fatal outcome.

MR diffusion tensor imaging and fiber tracking in 5 spinal cord astrocytomas.

Spinal cord astrocytomas are rare neoplasms that can result in alteration of the spinal cord structural integrity, which can be assessed by using diffusion tensor imaging methods. Our objective was to visualize the deformation of the posterior spinal cord lemniscal and corticospinal tracts in 5 patients with low-grade astrocytomas compared with 10 healthy volunteers by using 3D fiber-tracking reconstructions.

[Endoscope-assisted biopsy for the diagnosis of neurosarcoidosis]. / Biopsie endoscopique diagnostique d'un cas de neurosarcoïdose.

A 56-year-old woman was followed in the neurological department for febrile mental confusion. The diagnosis of sarcoidosis was suggested on the ground of associated abdominal lymphadenopathy, elevated serum angiotensin-converting enzyme level, aseptic meningitis and intracranial hypothalamic lesion. Nevertheless, radiological, biological and histological analyses could not assert the diagnosis of systemic sarcoidosis. Six months later, cerebral MRI showed a recent enhanced nodule, located near the right choroid plexus, inducing a dilatation of the right temporal ventricular horn. A surgical endoscope-assisted biopsy of that lesion was decided. The endoscope was introduced in the right trapped temporal ventricle. The limits between normal and pathological tissues were clearly identified. The biopsy was thus accurately performed. Histological analysis definitely confirmed the diagnosis of neurosarcoidosis. No postoperative complication was noted. We report a case of neurosarcoidosis which was diagnosed by ventricular endoscope-assisted biopsy. The discussion stresses the potential advantages of endoscopy for the diagnosis of small periventricular lesions when ventricular dilatation is associated.

[Temporary vessel occlusion]. / Clampage vasculaire temporaire.

UNLABELLED: In many situations, temporary artery occlusion is an integral component of aneurysm surgery. The use of temporary clip may allow safer and easier aneurysmal dissection and clipping. Several points, concerning the duration and overall risks of temporary occlusion and the method of choice for cerebral function monitoring have to be discussed. MATERIAL AND METHODS: Non exhaustive review of neurosurgical literature. DISCUSSION: Temporary clip application decreases the risk of intraoperative aneurysmal rupture. The analysis of data published in the literature showed that several questions remain open concerning the optimal method of neuroprotection and cerebral function monitoring, as well as the limit of occlusion duration. Other clinical trials are needed to assess the efficacy and safety of this technique.

[Endoscope-assisted microsurgery for invasive endo- and suprasellar pituitary macroadenomas: a consecutive retrospective study with 13 patients]. / Endoscopie et traitement chirurgical des macroadénomes hypophysaires endo- et suprasellaires invasifs. Une série consécutive rétrospective de 13 patients.

BACKGROUND AND PURPOSE: Surgery of invasive endo- and suprasellar pituitary macroadenomas remains difficult. The records of 13 consecutive patients who underwent transsphenoidal surgery were analyzed in order to evaluate advantages and limitations of endoscopy for surgery of invasive pituitary macroadenomas. METHODS: A transseptal transsphenoidal intersepto-columellar approach was performed with a nasal 0-degree endoscope. Removal of the macroadenoma was performed under the control of a microscope. When the tumor seemed to be completely removed with microscope, a rigid 30-degree endoscope was inserted in the intrasellar and suprasellar regions in order to detect residual adenoma tissue. These residues were removed when technically possible. RESULTS: No rhinologic complication was noted. In 7 patients, the intra- and suprasellar endoscopic view detected a tumor residue which could be removed in each case. Two cases of cerebrospinal fluid leakage occurred during the complementary tumor resection. Two cases of diabetes insipidus and two of rhinorrhea were reported postoperatively. The analysis of the postoperative MRIs showed a complete removal in 23% of the patients (3/13), 75 to 100% removal in 54% of the patients (7/13), 50 to 75% removal in 8% of the patients (1/13) and 50% removal in 15% of the patients (2/13). More than 75% removal was thus achieved in 77% of the patients (10/13). The mean follow-up was 27.2 months. CONCLUSIONS: Rhinologic morbidity was reduced with the endoscopic endonasal approach. Endoscopy complemented with a microscope offered an optimal view of the intra- and suprasellar regions. Endoscopy also improved tumor resection of the invasive endo- and suprasellar pituitary macroadenomas by visualizing hidden suprasellar tumor residues. However, endoscopy was associated with a higher rate of postoperative rhinorrhea.

Cross-neurotization of the caudal brachial plexus with the contralateral C-8 ventral nerve branch in the cat. Potential surgical applications, effects of graft collection on the healthy donor limb and results.

Contralateral transfer of the right, eighth ventral nerve branch (C8) (C8 cross-transfer - C8CT) was performed in 6 adult cats, in which the caudal part of the left brachial plexus (C8 and T1) had been severed, in order to mimic nerve root avulsion. Clinical and electrophysiological parameters, muscle contraction force measurements and histology were used to evaluate the effects of the surgery in a 14- to 36-month follow-up. The right forelimb (donor side) was clinically normal (no lameness) in all the cats at the end of the study. Electromyography performed 14 days after surgery revealed denervation fibrillation potentials in both forelimbs. Fibrillation potentials disappeared in all the cats at the end of the study. Direct stimulation of the right C8 ventral branch induced motor and sensory evoked potentials in the left limb muscles in all the cats. The left to right contraction ratio of the extensor carpi radialis muscle was approximately 1. This experimental study demonstrates that C8CT enables re-innervation of the contralateral brachial plexus and allows the establishment of new functional neuromuscular units. This can in turn enable the restoration of function, and could potentially lead to partial recovery after caudal brachial plexus avulsion in the cat.

Comparison of dopamine and norepinephrine after traumatic brain injury and hypoxic-hypotensive insult.

After severe brain trauma, blood-brain barrier disruption and alteration of cerebral arteriolar vasoreactive properties may modify the cerebral response to catecholamines. Therefore, the goal of the present study was to compare the effects of dopamine and norepinephrine in a model of brain injury that consisted of a weight-drop model of injury complicated by a 15-min hypoxic-hypotensive insult (HH). Sprague-Dawley rats (n = 7 in each group) received, after brain injury, an infusion of either norepinephrine (TNE group) or dopamine (TDA group) in order to increase cerebral perfusion pressure (CPP) above 70 mm Hg. In addition, a control group (C group, no trauma) and a trauma group (T group, brain injury, no catecholamine infusion) were studied. Mean arterial pressure (MAP), intracranial pressure (ICP, intraparenchymal fiberoptic device), and local cerebral blood flow (LCBF, extradural laser-Doppler fiber) were measured throughout the protocol. In T group, brain injury and HH induced a decrease in CPP (by an increase of ICP and a decrease of MAP), and a decrease of LCBF. Both norepinephrine and dopamine failed to increase CPP, and ICP was significantly higher in TNE and TDA groups than in T group. Interestingly, norepinephrine was not able to alleviate the decrease in MAP. Neither norepinephrine or dopamine could induce an increase of MAP. LCBF decreased similarly in T, TNE and TDA groups. In conclusion, norepinephrine and dopamine are not able to restore values of CPP above 70 mm Hg in a model of severe brain trauma. Furthermore, their systemic vasopressor properties are altered.

Partial return of motor function in paralyzed legs after surgical bypass of the lesion site by nerve autografts three years after spinal cord injury.

Spinal cord injuries often result in irreversible loss of motor and somatosensory functions below the lesion level. Treatment is limited to physiotherapy aimed at compensating disability. We previously showed that re-establishment of tissue continuity can be achieved in animal models through nerve autografts implanted between the rostral spinal ventral horn and the caudal ventral roots. Rostral motor neuron axons could thus reach peripheral targets, leading to some return of motor function. We used a similar approach in a paraplegic patient with stabilized clinical states three years after spinal cord traumatic damage at the T9 level. Three segments from autologous sural nerves were implanted into the right and left antero-lateral quadrant of the cord at T7-8 levels, then connected to homolateral L2-4 lumbar ventral roots, respectively. Eight months after surgery, voluntary contractions of bilateral adductors and of the left quadriceps were observed. Muscular activity was confirmed by motor unit potentials in response to attempted muscle contraction. Motor-evoked potentials from these muscles were recorded by transcranial magnetic stimulation. These data support the hypothesis that muscles have been re-connected to supra-spinal centers through motor neurons located in the rostral stump of the damaged cord. They suggest that delayed surgical reconstruction of motor pathways may contribute to partial functional recovery.

Sensorimotor cortical activity in patients with complete spinal cord injury: a functional magnetic resonance imaging study.

Residual activation of the cortex was investigated in nine patients with complete spinal cord injury between T6 and L1 by functional magnetic resonance imaging (fMRI). Brain activations were recorded under four conditions: (1) a patient attempting to move his toes with flexion-extension, (2) a patient imagining the same movement, (3) passive proprio-somesthesic stimulation of the big toes without visual control, and (4) passive proprio-somesthesic stimulation of the big toes with visual control by the patient. Passive proprio-somesthesic stimulation of the toes generated activation posterior to the central sulcus in the three patients who also showed a somesthesic evoked potential response to somesthesic stimulation. When performed under visual control, activations were observed in two more patients. In all patients, activations were found in the cortical areas involved in motor control (i.e., primary sensorimotor cortex, premotor regions and supplementary motor area [SMA]) during attempts to move or mental imagery of these tasks. It is concluded that even several years after injury with some local cortical reorganization, activation of lower limb cortical networks can be generated either by the attempt to move, the mental evocation of the action, or the visual feedback of a passive proprio-somesthesic stimulation.

Strong expression of GFAP mRNA in rat hippocampus after a closed-head injury.

We investigated the spatiotemporal GFAP mRNA expression over a period of 11 days following brain injury in rats caused by impact acceleration, which is known to produce diffuse axonal injury (DAI). We observed widespread GFAP mRNA expression throughout the brain, which was more rapid and intense in the hippocampus. This expression was obvious in most animals 2 days after injury and appeared maximal at day 6. Although it decreased by day 11, the level of expression remained high compared with control levels. We noted slight differences in time of onset and the magnitude of the response between hippocampus and white matter structures or cortical areas. The different mechanisms able to trigger this response are discussed in regard to histopathological changes observed in DAI models.

Comparative effect of alpha-MSH and b-FGF on neurite extension of fetal rat spinal cord neurons in culture.

Basic fibroblast growth factor (b-FGF) and alpha melanocyte stimulating hormone (alpha-MSH) were tested for their ability to promote axonal elongation on E14 fetal rat spinal cord cell culture, and to support cell survival. A similar development of neurite was observed in alpha-MSH treated cultures or in control cultures, with an axonal length ranging from 87.50 microns to 195.60 microns on day 3. Complete cell death occurred after 6 days of incubation. Whatever the concentration of b-FGF used (0.312-2.5 ng/ml), a significant increase (1.2- to 1.4-fold) in neurite length was observed, with neuronal survival up to 9 days.

Regrowth of the rostral spinal axons into the caudal ventral roots through a collagen tube implanted into hemisected adult rat spinal cord.

OBJECTIVE: A collagen tube was used to guide axonal regrowth from the spinal cord to the periphery to contribute to improvement of paralysis after lower thoracic spinal cord injury. METHODS: The spinal cords of adult male Sprague-Dawley rats were lesioned by removing the left hemicord from T12 to 5 mm below this level and additionally sectioning all left lumbar ventral roots. In experimental animals (n = 9), a collagen tube was inserted into this gap, spanning the rostral hemisected cord to the caudal sectioned lumbar ventral roots (gap, 7 mm). In control animals (n = 6), no treatment was performed. RESULTS: Six months after surgery, the return of some tension and resistance of the paralyzed hindlimb muscles was observed in all experimental rats except the untreated controls. Nine months postoperatively, muscle action potentials were recorded from the target muscles of the experimental animals while electrostimulating the tissue continuity within the collagen tube. Horseradish peroxidase retrograde labeling showed that the neurons in the rostral cord near the implantation site regrew into the reconnected lumbar ventral roots. Histological examination indicated numerous myelinated axons in the reconnected root pathways and newly formed endplates in the target muscles. No axonal regeneration was found in the control rats. CONCLUSION: These results indicate that the rostral spinal axons can regrow into the caudal sectioned and reconnected ventral roots through a collagen tube, thus innervating the denervated peripheral targets in adult rats after spinal cord injury. This surgical repair model also provides a means for testing the use of trophic factors that may further promote axonal regeneration.

Common origin of the arterial blood flow for an arteriovenous medullar fistula and the anterior spinal artery: a case report.

A common origin of the blood supply to a dural arteriovenous malformation and to the spinal cord from the same segmental artery is very rare. This obviously contraindicates embolization of the fistula. Demonstrating the location of the normal spinal blood supply system is therefore mandatory to avoid postoperative complications. The visualization of the normal blood vessels can be masked by a steal phenomenon, but it must at all costs be obtained. The authors describe one such case.

Use of a collagen-based sealant to prevent in vivo epidural adhesions in an adult rat laminectomy model.

OBJECT: The authors investigated the effect of a collagen-based sealant, Gel Amidon Oxydé (GAO), in the prevention of epidural scar adhesions in an adult rat model of laminectomy. METHODS: Seventy-two adult Sprague-Dawley rats underwent an L5-6 laminectomy, after which the dura mater and the left L-4 and L-5 nerve roots were exposed. In the 36 animals that received GAO, the sealant was applied over the dura and around the nerve roots, and it was used to fill the laminectomy cavity before it polymerized. In 36 control animals, the same surgical treatment was performed, but the rats did not receive GAO. During the early postoperative period, a significant decrease in the occurrence of epidural hematoma was found in the GAO-treated rats. In contrast to findings in control rats, a thin white connective tissue layer was found between the dura and surrounding muscles after GAO had degraded and been absorbed. One month posttreatment, no epidural scar adhesion was found between the tissue layer and the dura in the GAO-treated animals. Three months postoperatively, both gross inspection and histological examination further confirmed that formation of epidural adhesions was significantly inhibited in the rats treated with GAO. No special inflammatory reaction was observed, and the healing of skin and muscle lesions was not affected by either treatment. CONCLUSIONS: The data obtained in this study suggest that the GAO collagen-based sealant may be an effective biomaterial to prevent epidural adhesions in vivo after laminectomy.

Innervation of the caudal denervated ventral roots and their target muscles by the rostral spinal motoneurons after implanting a nerve autograft in spinal cord-injured adult marmosets.

OBJECT: The authors conducted a study to determine the effects of using a nerve autograft (NAG) to promote and guide axonal regrowth from the rostral spinal cord to the caudal lumbar ventral nerve roots to restore hindlimb motor function in adult marmosets after lower thoracic cord injury. METHODS: Nine animals underwent a left-sided hemisection of the spinal cord at T-12 via left-sided T9-L3 hemilaminectomy, with section of all ipsilateral lumbrosacral ventral nerve roots. In the experimental group (five animals), an NAG obtained from the right peroneal nerve was anastomosed with the sectioned and electrophysiologically selected lumbar ventral roots (left L-3 and L-4) controlling the left quadriceps muscle and then implanted into the left ventrolateral T-10 cord. In the control group (four animals), the sectioned/selected lumbar ventral roots were only ligated. After surgery, all marmosets immediately suffered from complete paralysis of their left hindlimb. Five months later, some clinical signs of reinnervation such as tension and resistance began to appear in the paralyzed quadriceps of all experimental animals that received autografts. Nine months postoperatively, three of the five experimental marmosets could maintain their lesioned hindlimb in hip flexion. Muscle action potentials and motor evoked potentials were recorded from the target quadriceps in all experimental marmosets, but these potentials were absent in the control animals. Horseradish peroxidase retrograde labeling from the distal sectioned/reconnected lumbar ventral roots traced 234+/-178 labeled neurons in the ipsilateral T8-10 ventral horn, mainly close to the NAG tip. Histological analysis showed numerous regenerating axons in this denervated/reconnected nerve root pathway, as well as newly formed motor endplates in the denervated/reinnervated quadriceps. No axonal regeneration was detected in the control animals. CONCLUSIONS: These data indicate that the rostral spinal neurons can regrow into the caudal ventral roots through an NAG, thereby innervating the target muscle in adult marmosets after spinal cord injury.

Experimental evaluation of bilayered human collagen as a dural substitute.

Many substances have been tried as possible dural substitutes, and different tissues and materials have been evaluated for use in dural repair; however, an entirely satisfactory solution still remains to be found. The authors report an experimental study involving the closure of dural defects in dogs with a new biomaterial, resorbable bilayered human placental collagen, using two types of collagen material. These include a collagen bilayered dural substitute made of oxidized type III + I collagen layer covered by a type IV oxidized collagen film (collagen dural substitute I) and a collagen bilayered dural substitute made of oxidized type III + I collagen layer covered by a type III + I collagen film (collagen dural substitute II). Macroscopic and histological examination, performed over a period of between 15 and 180 days after implantation, showed the resorption of collagen graft and formation of a neomembrane that looked like a neodura within 3 months. No infection and no cerebrospinal fluid fistulae were noticed. Nevertheless, one slight cerebromembranous adhesion was found with collagen dural substitute II. The authors suggest that human resorbable collagen biomaterial could be used as a very satisfactory dural substitute.

Experimental reinnervation of a strap muscle with a few roots of the phrenic nerve in rabbits.

In order to compare application of the roots of the phrenic nerve to the ansa hypoglossi for laryngeal muscle neurotization, 1 or more roots from the phrenic nerve were implanted into the right sternothyroid (RST) muscle of rabbits (n = 36). Controls were intact animals (in which RST innervation is provided by the ansa; n = 6) and denervated ones (n = 6). At 66 +/- 2 days (mean +/- SE) after neurotization, during quiet breathing, inspiratory electromyographic activity and isometric contraction force were observed in all reinnervated RST muscles (n = 24). During maximal inspiratory effort, electromyographic activity and force increased. In animals reinnervated by the C4 root alone, forces (46.22 +/- 7.8 g) were significantly higher than in intact animals (10.83 +/- 5.0 g). Retrograde labeling proved the phrenic origin of the neurotization. Electromyography of the diaphragm was recorded. We conclude that in rabbits, neurotization of a strap muscle by 1 or 2 roots of the phrenic nerve allows inspiratory contraction, even during quiet breathing. Such inspiratory activity is not observed in sternothyroid muscles of intact animals innervated by the ansa hypoglossi.

Cervical anatomy of phrenic nerve roots in the rabbit. European Group for Research on the Larynx.

The cervical anatomy of the different nerve contributions that constitute the phrenic nerve (phrenic nerve roots and accessory phrenic nerve) were studied in rabbits. In 55 dissections, 6 main root arrangement types were observed. The roots that issued from the fourth and fifth cervical nerves (C4 and C5 roots) were constant. The C4 root was either short or long. The C6 root was at times absent, or sometimes double. An accessory phrenic nerve was present in 43% of the right and 28% of the left dissections. The distribution of the phrenic nerve roots often displayed left-right asymmetry. We conclude that a better knowledge of the cervical anatomy of the phrenic nerve is useful both in physiological studies involving diaphragm denervation and in experimental laryngeal reinnervation.

Functional MR imaging and traumatic paraplegia: preliminary report.

PURPOSE: To evaluate residual activity in the sensorimotor cortex of the lower limbs in paraplegia. METHODS: 5 patients suffering from a complete paralysis after traumatic medullar lesion (ASIA=A). Clinical evaluation of motility and sensitivity. 1. Control functional MR study of the sensorimotor cortex during simultaneous movements of hands, imaginary motor task and passive hands stimulation. 2. Concerning the lower limbs, 3 fMRI conditions: 1-patient attempts to move his toes with flexion-extension, 2-mental imagery task of the same movement, 3-peripheral passive proprio-somesthesic stimulation (squeezing) of the big toes. RESULTS: Activations were observed in the primary sensorimotor cortex (M1), premotor regions and in the supplementary motor area (SMA) during movement and mental imaginary tasks in the control study and during attempt to move and mental imaginary tasks in the study concerning the lower limbs. Passive somesthesic stimulation generated activation posterior to the central sulcus for 2 patients. CONCLUSION: Activations in the sensorimotor cortex of the lower limbs can be generated either by attempting to move or mental evocation. In spite of a clinical evaluation of complete paraplegia, fMRI can show a persistence of sensitive anatomic conduction, confirmed by Somesthesic Evoked Potentials.