Biomedical subjects

Alexis Faure

Publications and source records attributed to Alexis Faure.

11 recordsLinked to original sources

PubMed2006

Endoneural metastasis of the sciatic nerve disclosing the relapse of a renal carcinoma, four years after its surgical treatment.

METHODS: To report on an exceptional case of renal metastasis. Indeed, endoneural metastases of peripheral nerves are thought to be exceptional, and such an event has not yet been ascribed to a renal carcinoma. RESULTS: We report on a sciatica leading to the discovery of a tumour of the right thigh which proved to be an endoneural metastasis of the sciatic nerve from a renal carcinoma surgically removed 4 years before. CONCLUSION: A thorough palpation of peripheral nerve can help recognise such metastases in patients previously diagnosed with renal carcinoma.

Carcinoma, Renal Cell↗

PubMed2006

Cervical spondylitis due to Neisseria meningitidis.

The diverse clinical spectrum of meningococcal infections includes frequent clinical forms, such as meningitis or septicemia, and uncommon manifestations, such as septic arthritis. Neisseria meningitidis is not generally considered to be a causative agent of osteoarticular infections. We report the first case of acute primary cervical spondylitis in a 48-year-old man.

Journal Article↗

PubMed2005

Learning-dependent activation of Fra-1: involvement of ventral hippocampus and SNc/VTA complex in learning and habit formation.

Although the effect of overtraining on learning processes in rats has long been studied, only few studies have specifically assessed the differential involvement of brain areas in habit formation. We used the analysis of expression of the immediate early gene Fra-1 as a tool to differentiate the areas involved in training and overtraining. Behavioural experiments showed that instrumental performance (signalled and non-signalled instrumental tasks), but not pavlovian conditioned responses, were no longer under the control of the incentive value of the reward after overtraining. The number of Fra-1 expressing neurons was increased in SNc/VTA and ventral hippocampus after training in all groups independently of behavioural performance. After overtraining, the number of learning-induced Fra-1 immunoreactive neurons remained increased in the SNc/VTA. However, in CA1, it significantly decreased in the signalled instrumental group, whereas it further increased in the pavlovian group, with no modulation in non-signalled instrumental animals. The increase in the number of Fra-1 neurons observed after training in SNc/VTA and ventral hippocampus suggests that a general underlying incentive process regulates Fra-1. Moreover, the sustained increased expression of Fra-1 in the SNc/VTA after instrumental overtraining could reflect a possible role of dopaminergic neurons in habit formation.

Animals↗

PubMed2005

Lesion to the nigrostriatal dopamine system disrupts stimulus-response habit formation.

Acquisition and performance of instrumental actions are assumed to require both action-outcome and stimulus-response (S-R) habit processes. Over the course of extended training, control over instrumental performance shifts from goal-directed action-outcome associations to S-R associations that progressively gain domination over behavior. Lesions of the lateral part of the dorsal striatum disrupt this process, and rats with lesions to the lateral striatum showed selective sensitivity to devaluation of the instrumental outcome (Yin et al., 2004), indicating that this area is necessary for habit formation. The present experiment further explored the basis of this dysfunction by examining the ability of rats subjected to bilateral 6-hydroxydopamine lesions of the nigrostriatal dopaminergic pathway to develop behavioral autonomy with overtraining. Rats were given extended training on two cued instrumental tasks associating a stimulus (a tone or a light) with an instrumental action (lever press or chain pull) and a food reward (pellets or sucrose). Both tasks were run daily in separate sessions. Overtraining was followed by a test of goal sensitivity by satiety-specific devaluation of the reward. In control animals, one action (lever press) was insensitive to reward devaluation, indicating that it became a habit, whereas the second action (chain pull) was still sensitive to goal devaluation. This result provides evidence that the development of habit learning may depend on the characteristics of the response. In dopamine-depleted rats, lever press and chain pull remained sensitive to reward devaluation, evidencing a role of striatal dopamine transmission in habit formation.

Animals↗

PubMed2004

Dynamic effects of a 9 mm missile on cadaveric skull protected by aramid, polyethylene or aluminum plate: an experimental study.

BACKGROUND: Most military helmets are designed to prevent penetration by small firearms using composite materials in their construction. However, the transient deformation of the composite helmet during a non penetrating impact may result in severe head injury. METHOD: Two experimental designs were undertaken to characterize the extend of injuries imparted by composite panels using in protective helmets. In the first series, 21 dry skulls were protected by polyethylene plates, with gaps between the protective plate and skull ranging from 12 to 15 mm. In another design, using 9 cadavers, heads were protected by aluminum, aramid, or polyethylene plates. Specimens were instrumented with pressure gauges to record the impact response. The ammunition used in these experiments was 9 mm caliber and had a velocity of 400 m/s. A macroscopic analysis of the specimens quantified fractures and injuries, which were then related to the measured pressures. RESULTS: Protective plates influenced both the levels of injury and the intracranial pressure. Injuries were accentuated as the plates was changed from aluminum to composite materials and ranged from skin laceration to extensive skull fractures and brain contusion. Fractures were associated with brain parenchymal pressures in excess of 560 kPa and cerebrospinal fluid pressure of 150 kPa. An air gap of a few millimeters between the plate and the head was sufficient to decrease these internal pressures by half, significantly reducing the level of injury. CONCLUSIONS: Ballistic helmets made of composite materials could be optimized to avoid extensive transient deformation and thus reduce the impact and blunt trauma to the head. However, this deformation cannot be completely removed, which is why the gap between the helmet and the head must be maintained at more than 12 mm.

Acceleration↗

PubMed2004

Spontaneous sphenoid sinus mucocele revealed by meningitis and brain abscess in a 12-year-old child.

Sphenoid sinus mucocele is an uncommon lesion related to inflammatory disease that is diagnosed after surgery or a traumatic event. This report describes an unusual case revealed by bacterial meningitis and cerebral abscess in a 12-year-old child. CT and MR imaging allowed precise extension to the skull base in preoperative management and follow-up investigations. Endoscopic transnasal marsupialisation of the mucocele and antibiotic therapy led to complete remission. There was no evidence of recurrence after 6 months, which suggests that sphenoid mucoceles, regardless of size and complications, can be treated by endoscopic sinus surgery.

Brain Abscess↗

PubMed2003

Removal of ethmoidal malignant tumors by the isolated paralateronasal approach with resection of the cribriform plate and the dura mater.

OBJECTIVE: A series of ethmoidal tumors was resected by an entirely extracranial approach through a lateral rhinotomy incision, with partial maxillectomy and removal of the cribriform plate and dura mater from below. METHODS: Thirty-four consecutive patients (32 male, 2 female; mean age 64 years, range 45-78) with malignant tumors of the ethmoid sinus were operated by this technique between July 1998 and February 2002. All had complete tumor resection, including the cribriform plate and the dura mater. Excision was performed en bloc 23 times (68%). Although cerebral involvement was encountered in four cases (T4 IC), this technique was adequate for tumor resection, together with corticectomy when necessary. The method used for tumor resection and rebuilding of the anterior skull base is described in detail. RESULTS: There were no immediate postoperative deaths. One patient developed pneumococcal meningitis with cerebrospinal fluid leakage as a result of a technical error and required further surgery. Four patients presented a confusion syndrome that regressed during the hospital stay, 2 complained of transient diplopia, and 4 had hematoma of the abdominal wall. Mean follow-up of 10.4 months (1-41 months) is still too short to reach definitive conclusions about oncologic results. CONCLUSIONS: This approach is particularly suitable for removal of tumors in contact with or invading the cribriform plate. Tumor resection is as extensive as with the traditional mixed approach, but does not require the frontal lobes to be drawn aside.

Adenocarcinoma↗

PubMed2003

Pudendal nerve entrapment as source of intractable perineal pain.

Perineal pain caused by pudendal nerve entrapment is a rarely reported entity, with only a handful of cases in the modern literature. A 25-yr-old male medical student had refractory unilateral orchialgia for 32 mo and concomitant proctalgia for 14 mo. Pain was positional in nature, exacerbated by sitting and partially relieved when standing or recumbent. Pudendal nerve entrapment was diagnosed clinically, with computed tomography-guided nerve blocks providing temporary relief. A prolonged left pudendal nerve distal motor latency on electrodiagnostic testing later confirmed the diagnosis. At surgery, the left pudendal nerve was found flattened in the pudendal canal of Alcock and in contact with the sharp inferior border of the sacrospinous ligament. After surgical decompression and rehabilitation, the patient experienced significant relief of pain and returned to medical school. This case suggests pudendal nerve entrapment should be considered in the differential diagnosis of chronic urogenital or anorectal pain, particularly if the pain is aggravated by sitting or if there is a history of bicycle riding.

Adult↗

PubMed2002

Hajdu-Cheney syndrome and syringomyelia. Case report.

This 7-year-old boy with Hajdu-Cheney syndrome presented with cervical syringomyelia related to rapidly progressing platybasia. Decompressive craniectomy provided temporary improvement, and his clinical status was eventually stabilized after external immobilization, according to findings at 2.5 years of follow up. In a review of the literature the authors found 57 cases of the syndrome, only three of which were associated with syringomyelia. The youth of the patient, the severe form and rapid course of the disease, and the very specific anatomical conditions related to cranial and facial deformities raised various therapeutic problems.

Child↗

PubMed2002

Inverted-hook occipital clamp system in occipitocervical fixation. Technical note.

The authors describe an occipitocervical fixation procedure in which they use inverted occipital hooks inserted through a burr hole drilled in the squamous part of the occipital bone. Fifteen patients with unstable lesions of the occipitocervical junction underwent occipitocervical internal fixation. The mean follow-up period was 21 months (range 2-63 months). No implant failed, and postoperative immobilization was not required. The placement of a posterior occipitocervical graft (for which fusion is uncertain) can be avoided in certain conditions.

Adult↗

PubMed2002

Arachnoiditis ossificans of the cauda equina. Case report and review of the literature.

The authors describe a case of arachnoiditis ossificans (AO) of the cauda equina. The lesion is a rare pathological entity usually confined to the thoracic and high lumbar regions that can cause progressive spinal cord and cauda equina compression, inducing severe neurological deterioration. The authors analyze the clinical symptoms, radiological features, histological data, and treatment options relating to this case and 13 others described in the literature; additionally, they consider the possible mechanisms responsible for ossification of the leptomeninges. Although clustered arachnoidal cells are usually implicated in its pathogenesis, an environment induced by arachnoiditis and disturbed cerebrospinal fluid flow appears to be a more important factor. A therapeutic strategy is proposed for AO for which no effective treatment currently exists.

Adult↗