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Biomedical subjects

J M González-Darder

Publications and source records attributed to J M González-Darder.

At least 19 recordsLinked to original sources
PubMed2006

Memory lateralization with 2 functional MR imaging tasks in patients with lesions in the temporal lobe.

BACKGROUND: Previous studies to determine memory lateralization with functional MR imaging (fMRI) have used encoding or recall tasks. The convergence between the results of both tasks, however, is unknown. OBJECTIVE: The objective of this study was to investigate hemispheric asymmetries of temporal lobe activity (parahippocampus and fusiform gyri) in patients with temporal lesions by using both kinds of fMRI tasks. METHODS: By using blood oxygenation level-dependent fMRI, hemispheric asymmetries of 25 consecutive patients admitted for presurgical evaluation of memory and 12 healthy control participants were studied. Activation was induced by using the picture-encoding task (processing of complex scenes) and the hometown-walking task (requiring mental navigation through one's hometown by using landmarks given by participants themselves). RESULTS: Results in the control group showed that both tasks activated the parahippocampus similarly. The picture-encoding task, however, yielded greater posterior activations in the parahippocampus than did the hometown-walking task. As observed in other studies, more than half the patients showed contralesional representation of memory in each task. It is important to note that estimated memory lateralization from each task was different in 30% of patients, and several cases showed clear discrepancies between both tasks. CONCLUSION: Although previous studies showed that both tasks were useful for evaluating memory lateralization, the present study suggested that the administration of both tasks is necessary for presurgical evaluation of memory lateralization in patients with lesions in the temporal lobe. Therefore, both encoding and recall processes should at least be considered in the evaluation of memory.

Adult↗
PubMed2006

[Development of the anterior cervical postdiscectomy arthrodesis: bone graft, plate, intersomatic cage and plate-cage].

The surgical techniques for anterior cervical postdiscectomy arthrodesis are reviewed, including bone graft, cervical plates, intervertebral cages and plate-cage systems. The biomechanical advantages of each method are discussed. An alternative to arthrodesis are simple discectomy and arthroplastia with disc prosthesis. Integrated plate-cage systems are the final result in the evolution of the cervical arthrodesis developments. The available plate-cage systems are described.

Arthrodesis↗
PubMed2004

Intraorbital arteriovenous malformation: case report.

An intraorbital arteriovenous malformation became symptomatic without exophthalmos but with chemosis and bruit of the left eye. The patient underwent only surgical treatment. The orbital rim was removed through a fronto-orbital approach. The chemosis was corrected and postoperative magnetic resonance imaging and angiography confirmed complete removal of the malformation. Histopathological examination disclosed an arteriovenous malformation in the extrabulbar fatty tissue without invasion of the extraocular muscles or optic nerve. The differences between various types of intraorbital malformations are discussed.

Case Reports↗
PubMed2004

[Neurosurgical treatment of acoustic neuromas without indication for radiosurgery].

The aim of this paper is to review the specific problems of the microsurgical management of the acoustic neuromas not suitable for radiosurgical treatment , that is measuring more than 8 cc in volume or 2.5 cm in maximum diameter in the cerebelopontine angle. A total of 18 lesions have been included with a mean volume of 27.4 cc, representing a lesion measuring 3.8 cm in its three main diameters. The mean follow-up has been 48.7 months. There has been no mortality. All lesions were completely excised without recurrences. The anatomic conservation of the facial nerve was achieved in the 66.7% of the cases but the functional recovery (House-Brackmann grades I-II) was reached only in the 27.8%, without any grade I case. As permanent deficit all patients had postoperative cophosis, two had trigeminal hyposthesia with corneal anesthesia and one had a cerebellar deficit. The main conclussion is that the microsurgical radical resection of large acoustic neuromas not suitable for radiosurgical treatment is followed by a high postoperative morbidity mainly related with the facial nerve lesion. Therefore, it seems rationale to design specific strategies directed to reduce and alleviate these permanent deficits.

Adult↗
PubMed2003

[Surgical management of posterior communicating artery aneurysms based on computed tomographic angiography with three-dimensional reconstruction and without preoperative angiography].

OBJECTIVE: To demonstrate the usefulness of three-dimensional computed tomographic angiography (CT-3D-angiography) in the microsurgical management of aneurysms of the posterior communicating artery (PComA). MATERIALS AND METHODS: A series of 27 patients with aneurysms of the PComA diagnosed by means of CT-3D-angiography and without preoperative angiography (group A) were compared with a series of 34 cases diagnosed by cerebral angiography. The findings of the CT-3D-angiography, angiography, microsurgical exploration and clinical data were evaluated. RESULTS: A total of 75 aneurysms were diagnosed preoperatively in 66 patients and 3 additional lesions were found postoperatively in group A. The sensitivity of the CT-3D-angiography was 91.7% for diagnosis of any aneurysm with an specifity of 100%, being the snsibility of angiography a 100% and its specifity 94.9%. Mortality rate was 4.5% without differences between groups regarding clinical results or complications. Both the preoperative timing and hospitalization time were shorter in group A. CONCLUSION: The study of patients with acute subarachnoid hemorrhage with CT-3D-angiography allows a reliable diagnosis of PComA aneurysms. Moreover, provides usefull information for the microsurgical clipping. When compared with angiography in the diagnosis of PComA aneurysms, CT-3D-angiography allows to improve some health indicators with similar clinical results and complications.

Humans↗
PubMed2002

[Retropleural paraspinal approach in the treatment of anterolateral thoracic spinal diseases].

The personal experience in the treatment of the spinal and paraspinal thoracic pathology using the paraspinal retropleural approach is presented. A total of 18 patients with neoplastic, traumatic and discal lesions were operated on. Improvement of neurological disturbances and pain was noted in all patients. The surgical technique for spinal cord and root decompression and also for anterior and/or posterior stabilization of the spine is described. The paraspinal retropleural approach is compared with the anterior transthoracic approach. The advantages of the paraspinal retropleural approach are: low rate of complications; allows a very wide decompression of the neurological elements as well as an anterior and/or posterior stabilization of the spine by a single approach; and it can be easily tailored for each lesion. These advantages are enhanced in the management of lesions located in the upper thoracic or thoracocervical levels.

Adolescent↗
PubMed2002

[Surgical management of anterior communicating artery aneurysms based on computed tomographic angiography with three-dimensional reconstruction and without preoperative angiography].

OBJECTIVE: To demonstrate the usefulness of threedimensional computed tomographic angiography (CT- 3D-angiography) in the microsurgical management of aneurysms of the anterior communicating artery (AComA). MATERIALS AND METHODS: A total of 28 consecutive patients with ruptured aneurysms of the AComA diagnosed by means of CT-3D-angiography and without preoperative angiography were operated on. The findings of the CT-3D-angiography, microsurgical exploration and clínical data were evaluated. RESULTS: There were no false positive findings nor false negative findings in the diagnosis of the AComA aneurysms. The global sensibility of the examination was 87.9%. The CT-3D-angiography study shows a left A1 segment dominance in 53.6% of cases, a right A1 dominance in 14.3% of cases and both A1 segments of the same diameter in 32.1%. Aneurysms growing on the traject of the AComA were associated with both A1 segments of the similar diameter and an AComA traject pararell to the transverse plane. Aneurysms implanted on the A1-A2 junction were associated with a dominant homolateral A1 segment and an oblique AComA traject. Microsurgical management of the lesions was done a mean of 3.7 days after bleeding. CONCLUSION: The study of patients with acute subarachnoid hemorrhage with CT-3D-angiography allows a reliable diagnosis of AComA aneurysms. The examination gives some anatomical data that allow the study of the hemodinamic changes involved in the development of the aneurysms. Moreover, provides usefull information for the microsurgical clipping. CT-3D-angiography allows to improve some health indicators but its impact in the final result of the patients needs more clinical data.

Adult↗
PubMed2001

Microsurgical management of cerebral aneurysms based in CT angiography with three-dimensional reconstruction (3D-CTA) and without preoperative cerebral angiography.

OBJECTIVE: To study the possibilities of the microsurgical management of ruptured intracranial aneurysms with the sole preoperative information provided by computed tomography angiography with three-dimensional reconstruction (3D-CTA). METHODS: Patients were studied with 3D-CTA after diagnosis of subarachnoid hemorrhage. If the study had an adequate quality and revealed an aneurysm congruent with the clinical findings or neurological examination and/or with the location of the bleeding on computed tomography (CT) scan an early microsurgical clipping of the lesion was done. When the quality of the 3D-CTA study was not adequate or the quality being adequate displayed no lesions or the findings were not accurate enough to warrant direct microsurgical treatment, the patient was studied with cerebral digital subtraction (DS) angiography. A total of 44 consecutive patients harbouring a total of 47 intracranial aneurysms diagnosed by 3D-CTA and without preoperative DS angiography were submitted to microsurgical clipping and included in the study. RESULTS: The overall mortality was 15.9% and the favourable results evaluated 6 months after discharge by means of the Glasgow Outcome Scale reached 70.4%. All lesions were successfully clipped. Surgery was done a mean of 4.1 days after the admission bleeding. A total of four microlesions undiagnosed by 3D-CTA were found at surgery and clipped. Postoperative DS angiography and necropsy findings were also used as control of the 3D-CTA findings but no additional information was provided excepting the finding in DS angiography of an asymptomatic intracavernous aneurysm. Therefore the sensitivity of the 3D-CTA for diagnosis of symptomatic aneurysms was 100% and the overall sensitivity 90.4%. CONCLUSIONS: We have reached similar results in patients operated on with or without preoperative angiography. 3D-CTA provides very valuable anatomical information, which has an additional value in the microsurgical treatment of aneurysms of the anterior communicating artery complex. Finally, selected cases of ruptured intracranial aneurysms can be successfully managed with the preoperative information provided by 3D-CTA and without DS angiography.

Adolescent↗
PubMed2001

[Prognosis value of p53 gene and cellular proliferation factors in malignant supratentorial gliomas].

OBJECT: The aim of this study was to investigate prognosis value of p53 oncosuppresor gene and labeling index by MIB-1 and PCNA monoclonal antibodies in malignant gliomas. METHODS AND RESULTS: We operated 60 patient with malignant glioma between July 1994 and August 1998. Forty-five cases had the histopathological diagnosis of Glioblastoma Multiforme and fifteen cases of anaplastic astrocytoma or olygoastrocytoma. Initially we compare MIB-1/PCNA labeling index in eighteen cases. Patients < 40 years old, short period of symptoms preoperatively, only one cerebral lobe localization, total surgical exeresis, Karnofsky index > 70 postoperatively, low labeling index (MIB < 8.6%), forward radiotherapy treatment and surgical re-operation, were identified like favourable outcome factors in the uninvariable analysis. However to the multivariable analysis, only had outcome significance: patients < 40 years old, low labeling index, Karnofsky index > 70 postoperatively and surgical reoperation. CONCLUSIONS: On the basis of the results of current analysis, moreover classical factors associated with better outcome, low labeling index to Glioblastoma Multiforme have been noted in patients with longer survival, and must be included to conventional histopathological studies.

Adult↗
PubMed2001

[Post-discectomy cervical fusion. Clinico-radiological study comparing iliac crest bone graft, anterior cervical plate with bone graft and cage-plate GD].

OBJECTIVE: To compare clinical and radiologically three methods of cervical arthrodesis after anterolateral one-level discectomy for non-traumatic disk disease. MATERIALS AND METHODS: Three groups of patients were studied retrospectively. In group 1 (20 patients) a tricortical autologous iliac crest bone interbody graft was used. In group 2 (10 patients) the bone graft was associated to an anterior cervical plate (Stryker). In group 3 (10 patients) a cage-plate filled with iliac crest trabecular bone was implanted (plate-cage GD). Clinical and radiological parameters were recorded preoperatively and 6-9 months postoperatively. RESULTS: There was a significant clinical improvement in all three groups, with similar complications and hospitalization time. There were not hard-ware failures. There was a significant increase in the disc height in group 3 when compared with group 1 and a significant correction of the preoperative kyphosis in group 3 in relation to both group 1 and 2: There was a significant increase in postoperative radiological stability rate and also in the operative time in groups 2 and 3 when compared with group 1. CONCLUSIONS: Cervical arthrodesis after discectomy is an useful method for treatment of cervicobrachialgia. Arthrodesis with internal fixation achieves best clinical and radiological results and it has some other advantages in relation to bone graft artrhodesis. GD cage-plate minimizes the surgical and clinical problems associated with use of bone graft and cervical plate and reaches the best radiological performances.

Adult↗
PubMed2001

[Biomechanical evaluation of an anterior cervical plate-cage fixation system].

OBJECTIVES: The objective of this paper is to present the results of a biomechanical study of an original system of internal fixation of the anterior cervical spine after discectomy. MATERIAL AND METHODS: The system includes an intersomatic cage fixed to an anterior plate. The cage is placed in the intersomatic space after discectomy and is fixed to the plate with a screw. The plate is fasted to the vertebral bodies with two screws with an original blocking system. A polyethylene model of vertebral unit was tested after the placement of a 6 mm cage and 32 mm plate with 14 mm screws (plate-cage system). In a series of static studies the stiffness, the strength in the elastic limit and the ultimate or failure strength in extension, flexion, compression and torsion were calculated. The fatigue study was done in extension reaching 2.5 million cycles. The model was studied also in extension with the plate and intersomatic iliac crest grafts (plate-bone system). RESULTS: The stiffness in extension calculated for the plate-cage system was 4.16 Nm/mm, in flexión 0.56 Nm/mm, in compressión 822 N/mm and in torsión 0.46 Nm/degree. The extension stiffness of the plate-bone system was 4.29 N/mm. The plate-cage system had a strength in the elastic limit of 386.3 N in extension reaching 295 N in the plate-bone system. The ultimate strength in extension for the plate-cage system was 673.3 N and 585 N in the plate-bone system. The strength in the elastic limit and the ultimate strength were 223 N y 336 N in flexion respectively, 1976 N y 3374 N in compression and, finally, 295.7 N y 385 N in torsión. The plate-cage system reached a total of 2.5 million cycles before it broke or began its deformity. CONCLUSIONS: The results of this biomechanical study are compared in a favourably manner with those obtained in similar experiments for the intact functional cervical unit, Morscher plate and a monoblock plate-cage prototype.

Biomechanical Phenomena↗
PubMed2001

[Assessment of the degree of resection of high grade supratentorial gliomas with early postoperative magnetic resonance].

UNLABELLED: In this paper we report the results of a prospective study in which we evaluate the degree of tumor removal of 25 supratentorial high grade gliomas by means of an MRI performed in the early postoperative period. In all cases, there was preoperative enhancement 8 patients had been previously operated on while the others had their first operation. In all cases the postoperative early MRI was performed within the first week and in 15 within the first 3 days. In order to evaluate the degree of tumor removal the presence or not of enhancement was considered and if it existed, classified as linear or nodular. RESULTS: To avoid postsurgical artifacts it is important to perform the MRI as soon as possible after surgery, especially within the first 3 days. Generally, linear enhancement disappeared on subsequent follow-up examinations, showing that it probably does no represent residual, tumor while nodular enhancement usually does. Survival with the high-grade tumors was slightly higher in the group without postoperative enhancement or linear one than in the group with nodular enhancement but the difference was not significant.

Adult↗
PubMed1999

Surgical treatment of multiple neurofibromas of the ulnar nerve in segmental neurofibromatosis. Case report.

The case of an 18-year-old man with numerous neurofibromas along his left ulnar nerve is described. The patient had a painful mass in the medial third of the internal aspect of his left forearm, and two additional symptomatic painful masses were identified during clinical examination: one in the distal portion of the retroepitroclear groove and another near the Guyon tunnel in the wrist. The main symptom was neurogenic pain; however, sensory and motor disturbances were also present. No other stigma of neurofibromatosis (NF) was found, and no cases of NF were known in the patient's family. During surgery many neurofibromas were found; the three painful neurofibromas and some of the other larger lesions were microsurgically excised. The patient's symptoms fit the criteria for segmental NF or NF5. This is a very rare form of NF characterized by lesions located in a particular area of the body.

Adolescent↗
PubMed1995

Anticonvulsant effect of intraventricular antiepileptic drugs. Experimental study.

The effect of intraventricular administration of antiepileptic drugs on an experimental model of epileptic seizures in rats has been investigated. Animals were tested in the electroshock test measuring the time duration of the tonic phase of the convulsion. Drugs tested were sodium phenobarbital (200-500-1000 micrograms), phenytoin (50-100-200-500 micrograms), midazolam (100-200-500 micrograms) and sodium valproate (500-1000-2000 micrograms), delivered via a catheter stereotactically placed into the lateral ventricle. Control animals were tested with saline. All antiepileptic drugs showed different degrees of reduction in the duration of the tonic phase before reaching doses that produced neurological symptoms. Our results demonstrate the feasibility to control experimental seizures by means of intraventricular injection of antiepileptic drugs.

Animals↗
PubMed1994

Skin perfusion changes in experimental neuropathic pain: sciatic nerve constriction.

Laser Doppler flowmetry was used as a method of measurement of skin blood flow perfusion in an experimental rat model of neuropathic pain. The common sciatic nerve was microsurgically approached and four ligatures were loosely tied around the nerve (sciatic ligature group). Contralateral nerves were approached but not injured (sham procedure). All paws were studied before any surgical procedure (controls) and immediately, 24 h, 11 and 25 days after surgery. In each experiment, the skin perfusion was measured in the plantar surface of the hind paw, both in baseline conditions and after a heating test, where skin temperature around flowmeter probe reached 42 degrees C. The heating test produced an increase in skin perfusion that ranged between 70% and 80% in sham and normal paws. Nerve ligation induced no immediate changes in skin perfusion with a normal 65% increase after heating. However, 24 h later, baseline skin perfusion was significantly higher than preoperatively with smaller response to heating. This situation changed at 11 and 25 days, with baseline values significantly smaller than before surgery and responses to heating significantly higher. Nerve section in these previously ligated sciatic nerves produces a significant increase in skin perfusion. Our results suggest that vasomotor changes in the model of sciatic ligature are presumably related to a denervation hypersensitivity of skin blood vessels to vasoactive agents.

Animals↗
PubMed1994

Skin perfusion changes after sciatic nerve transection in the rat.

Laser Doppler flowmetry was used as a method of measurement of skin blood flow perfusion in an experimental rat model of peripheral nerve section. The common sciatic nerve was microsurgically approached and cleanly severed (sciatic transection group). Contralateral nerves were approached but not injured (sham procedure). All paws were studied before any surgical procedure (controls) and immediately, 24 hours, 11 and 25 days after surgery. In each experiment, the skin perfusion was measured in the plantar surface of the hind paw, both in baseline conditions and after a heating test, where skin temperature around flowmeter probe reached 42 degrees C. Sham operated paws showed no differences from control unoperated paws. The heating test produced an increase in skin perfusion that ranged between 70% and 80% in sham and normal paws. Sciatic nerve section produces an immediate increase of 36.7% in blood flow with an additional increase of 27.5% after heating. In the following studies, on days 1, 11 and 25 baseline skin perfusion showed no changes in relation to preoperative values and heating induced only a small increase in perfusion.

Animals↗
PubMed1993

Experimental microsurgical repair of spinal roots.

Three different methods of nerve repair were evaluated in an experimental model of spinal root injury. In adult rats, dorsal L4 roots were cleanly severed and repaired by microsurgical techniques. Anastomosis was performed by direct end-to-end suture, the arterial sleeve technique, or the interposition of a nerve graft. Results were evaluated 7, 10, and 14 weeks after surgery. Regeneration was studied by light and electron microscopy, showing a fair regenerative pattern in each group. The endoneurial connective response, including neovascularization, was more prominent after grafting. The artery sleeve technique is a very tedious procedure, and fibrosis around the artery and arachnoiditis were intense. A lack of continuity was found in 3 of 12 direct sutures. In conclusion, the best method for the reparation of nerve roots seems to be the interposition of a nerve graft.

Animals↗