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R Assaker

Publications and source records attributed to R Assaker.

At least 19 recordsLinked to original sources
PubMed2006

[Primitive malignant melanoma arising in a spinal nerve root. A case report].

We report the fourth case of primitive malignant melanoma arising in a spinal nerve root. A 39-year-old woman complained of one-year low back pain radiating to the right thigh and knee, and loss of 7 kg. Clinical examination found moderate quadricipital amyotrophy and hypoesthesia of anterior side of the thigh. MRI study demonstrated an enlargement of right L3 root with scalloping of the L3/L4 foramen. The T1-weighted MRI images showed a tumor hyperintensity, the T2-weighted images showed tumor isointensity and mild contrast enhancement. Due to the scalloping of L3/L4 foramen with root enlargement and slow evolution (more than one year between the first symptom and surgery without clinical worsening), the initial preoperative diagnosis was L3 schwannoma. After laminoarthrectomy and dural opening, a firm black lesion, well encapsulated and involved in a dorsal spinal root, was totally removed. The tumor was composed of irregular melanocytoid cells with high proliferation index (20%). Immunohistochemistry showed melanin, HMB-45 and S100 positivity, but reticulin was negative (that eliminates malignant melanocytic schwannoma). An extensive clinical and paraclinical research of other melanotic localisation was negative. So, the final diagnosis was intradural primitive malignant melanoma. Radiotherapy was performed on the site of the tumor. Fatal pulmonary metastasis occurred 18 months after surgery. The most common tumor with root enlargement and bony scalloping is the benign schwannoma. Despite the above described radiological features, MRI characteristics (hyperintensity when images are T1-weighted) suggest a melanocytic tumor, a tumor with a high adipose component or an intratumoral bleeding. Specific MRI sequences can eliminate adipose tissue tumor, but diagnosis between melanin and methemoglobin is still difficult. According to the index of proliferation, a primitive central melanocytic lesion can be a meningeal melanocytoma (considered as benign) or a primitive malignant melanoma. These tumors show identical protein expressions in immunohistochemistry, and their prognosis is very variable (some long-term remissions are reported for malignant melanomas and fast disseminations are described for meningeal melanocytomas treated by sub-total surgery). The L3/L4 foramen scalloping is unusual for a malignant lesion with theoretic high-speed development. The other 3 patients (reported in the literature) survive more than 3 years. The histological features of malignant lesion with benign clinical features lead to interrogation upon the actual pathologic classification.

Adult↗
PubMed2005

Management of delayed intracranial and intraspinal metastases of intradural spinal paragangliomas.

The preferential site of extra-adrenal paragangliomas is the head and neck region. However intradural spinal paragangliomas are commonly described and are considered as benign entities. We report the case of a paraganglioma of the cauda equina followed after complete surgical removal by intracranial and intraspinal cerebrospinal fluid metastases. Seven years after the first operation, a cystic cerebellar lesion was successfully treated by surgery. During a long follow-up, four locations in the posterior fossa, a lumbar recurrence and metastatic nodules at T6 and S1-S2 level were also discovered. Radiotherapy stopped the lesions' growth and allowed improvement of the neurological status. Through a review and analysis of the literature, we discuss the management of this unusual evolution.

Adolescent↗
PubMed2002

[Frontal sinus osteomas: neuro-ophthalmological complications].

Osteomas are the most frequent benign tumors of the paranasal sinuses. They often grow in the frontal sinus near the nasofrontal duct. They remain frequently asymptomatic and they tend to be an incidental finding on radiographic studies. Rarely, they extend out of the sinus limits. Two cases with neuro-ophthalmological complications are reported and discussed. A 19-year-old female presented with a progressive left visual impairment and orbital bone deformity. A CT-scan revealed a large calcified mass in both frontal sinuses, with left intraorbital and frontobasal extension. A 21-year-old man suffered from acute frontoethmoidal sinusitis. Radiological exams revealed a right frontal sinus osteoma with bilateral nasofrontal ducts obstruction. The frontal sinus cavities were filled with a large mucocele with intracranial extension. Both patients were successfully treated using frontobasal craniotomy with complete osteoma and mucocele removal and cranio facial bone reconstruction. Neuro-ophthalmological or intrasinusal complications of osteomas lead to radical treatment. CT-scan and MRI analysis for surgical purpose and strategy are emphased.

Adult↗
PubMed2001

Transpedicular screw placement: image-guided versus lateral-view fluoroscopy: in vitro simulation.

STUDY DESIGN: In vitro evaluation of monitoring screw placement using an image-guided system compared with the routine use of an image intensifier. OBJECTIVES: To compare a new computer-guided method of monitoring pedicle screw placement with a well-known method of monitoring using an image intensifier, using measurements of screw placement time and accuracy. SUMMARY OF BACKGROUND DATA: Pedicle screw placement relies on the identification of anatomic landmarks for the point of entry of the pedicle. The direction and depth of screw penetration are guided by an intraoperative lateral-view image intensifier. The use of frameless stereotaxy for computer-aided pedicle screw placement may increase the accuracy and safety of the screw insertion. To the authors' knowledge, there are no published data comparing these systems on the basis of operative time and screw placement accuracy. METHOD: Eight human cadaveric sections of five vertebrae each were used for an in vitro simulation of pedicle screw placement. Four spine surgeons were chosen to simulate the transpedicular screw placement. Each surgeon placed one screw into each pedicle of two spine sections (10 vertebrae, 20 screws). The surgeon was assisted by the lateral-view image intensifier on one spine section and by the navigational system on the second one. The four surgeons placed 80 pedicle screws. Forty screw placements were monitored by fluoroscopy and 40 by the image-guided navigational system. The time spent to place one screw was recorded, as well as the remarks by each surgeons on each method. Spines were rescanned, and the positions of the screws were compared between the group on which the image intensifier has been used and the group on which the navigational system had been used. RESULTS: In the image-guided technique group, one thoracic screw disrupted the lateral cortex of the pedicle, the average distance to the anterior wall of the body was 5 mm, and the average time for the insertion of one screw was 13.5 minutes. In the other group, two screws disrupted the inner cortex of a thoracic pedicle, the average distance to the anterior wall was 10.7 mm, and the average time for the insertion of one screw was 4 minutes. CONCLUSIONS: In vitro computer-aided pedicle screw insertion is more accurate than lateral-view fluoroscopy in the thoracic spine. The main disadvantage is the time consumption compared with that required by lateral-view fluoroscopy. The total time of the surgical operation should be decreased with the future development of these techniques.

Bone Screws↗
PubMed2001

Image-guided endoscopic spine surgery: Part I. A feasibility study.

STUDY DESIGN: A feasibility study was performed to determine the efficacy of computer assistance in endoscopic spine surgery. OBJECTIVES: To assess a new method for computer assistance based on image guidance during thoracoscopic or any endoscopic spine procedure. To evaluate the reproducibility, the sensitivity and the reliability of the technique first in vitro and second in clinical use. SUMMARY OF BACKGROUND DATA: The computer-based, image-guided surgery is now a routine tool used in open spine surgery. Exposure of the anatomy of the vertebra is needed for registration. This methodology is inapplicable in endoscopic approach. Fluoroscopic-based navigation combines the technology of image-guided surgery and C-arm fluoroscopy. The navigation is based on the fluoroscopic images acquired before surgery. This technology is applicable to endoscopic surgery but the navigation is based on fluoroscopic image. The computed tomography images are not exploited. There are no published data on a technique that allows image-guided surgery based on computed tomography and magnetic resonance imaging. METHOD: A laboratory study was performed on a thoracic human spine. One vertebra was marked on the right lateral side of the body with five titanium marks. A percutaneous reference frame was specifically designed to be placed in the pedicle of the same marked vertebrae. The reference frame acted as a 3D localizer and a registration tool. The spine model was scanned including the reference frame. A standard Stealth station treatment guidance platform (Medtronic, Sofamor Danek, Memphis, TN) was used for simulation. The registration was obtained using the reference frame. Twenty navigation procedure trials were done and the error was recorded based on the distance between the anatomical point and the corresponding virtual one. RESULTS: Registration was always possible using the stealth station and a standard spine navigational software (spine 3, Medtronic Sofamor Danek, Memphis, TN). The mean error after registration given by the computer was 0.96 mm. The mean error recorded during the navigation simulation was 1.6 mm. CONCLUSIONS: This technique allows the possibility of computed tomography and magnetic resonance imaging-based, image-guided endoscopic surgery. It is probable that in the near future, as image fusion technology improves, the fluoronavigation based on fluoroscopic images would enable to navigate on multimodal images. Otherwise the technique described in this article is the only reproducible one that allows computed-tomography-based computer assistance during endoscopic procedures.

Endoscopy↗
PubMed2001

Image-guided endoscopic spine surgery: Part II: clinical applications.

STUDY DESIGN: Endoscopic spinal procedures were performed under computed-tomography-based, image-guided assistance. OBJECTIVE: To assess the clinical feasibility of applying a methodology that allows image-guided assistance in endoscopic spinal surgery. SUMMARY OF BACKGROUND DATA: Endoscopic spinal procedures have become a part of the minimal invasive approaches to the spine. The main disadvantage of these techniques is the long learning curve and the lack of peroperative monitoring. Fluoroscopy does have disadvantages, such as positioning during surgery and the risk for radiation exposure. Fluoroscopy-based navigation has many advantages, however it is still based on preselected fluoroscopic images. There is no method that allows computed-tomography-based navigation in endoscopic conditions. METHODS: Two patients have been operated on using endoscopic approaches assisted by computed-tomography-based navigational system. One had a thoracoscopic approach for median calcified disc herniation and another one had an endoscopic posterior approach for resection of a sacro-iliac osteophyte. For each patient, a frame of reference had been placed percutaneously and scanned. The computed tomography images were registered to the anatomy using the geometry of the frame as fiducials. Navigation through endoscopic approaches was possible in both cases. RESULTS: In both cases navigation was reliable and a helpful monitoring to achieve the surgical goals through endoscopic approaches. CONCLUSIONS: There are some factors that make endoscopic spine surgery a difficult start. Image-guided spine surgery is technically feasible and clinically applicable in endoscopic approaches.

Adult↗
PubMed2001

Foramen magnum syndrome secondary to calcium pyrophosphate crystal deposition in the transverse ligament of the atlas.

STUDY DESIGN: This report illustrates two rare cases of foramen magnum syndrome caused by a retro-odontoid mass in which calcium pyrophosphate dihydrate crystals were found. OBJECTIVES: To analyze the preoperative studies and the diagnostic criteria and to discuss the surgical treatment. The present cases will be compared with previous ones described in the literature. SUMMARY OF BACKGROUND DATA: Deposition of calcium pyrophosphate dihydrate crystals occurs into the fibrous and hyaline cartilage of the joints and intervertebral discs of the spine. Half of the patients known to have a chondrocalcinosis had asymptomatic calcification in the odontoid region. Ten patients were published in the literature as having a spinal cord syndrome secondary to calcium pyrophosphate dihydrate deposition in the odontoid region. METHODS: In both cases the preoperative studies were analyzed, and the retro-odontoid mass was resected and histologically examined. Both had an anterior transoral approach and have been followed for 1 year. RESULTS: According to the preoperative radiographs the diagnosis was suspected and confirmed histologically. Transoral approach was done with no need in either case for a posterior stabilization. CONCLUSIONS: Compression of the spinal cord by calcium pyrophosphate dihydrate deposition may occur. The preoperative diagnosis may be highly suspected after radiographic study and histologically confirmed. Transoral resection is the treatment of choice. Posterior stabilization should be considered only in cases of craniovertebral instability.

Aged↗
PubMed2001

Occipital dermal sinuses: report of nine pediatric cases and review of the literature.

Occipital dermal sinuses (ODS) are rare dysraphic lesions resulting from defective separation of the ectoderm and neuroderm. These lesions are often diagnosed at birth and should be treated early because of potentially life-threatening complications. However, the pathogenesis of these rare lesions is still poorly understood, and there is no consensus about the optimal timing of surgery. We reviewed 9 pediatric cases of ODS operated in our department since 1982 and 79 other cases published in the literature during the last 50 years. Thirty-eight percent of these had neurological infection (meningitis or abscess), 22% had purely local infection and 40% were uncomplicated at the time of diagnosis. The incidence of infection was low during the first year of life. MRI was highly valuable to study the extent of the sinus and the content of the cyst. The outcome was regularly favorable after surgery. Surgery should however be undertaken with caution on account of the intimate relationship with venous structures, aggravated by postinfectious scarring when the patient is operated late. Considering the risks associated with surgery in neonates and the low incidence of infection during the first year, we advise performing surgery at around 6 months.

Brain Neoplasms↗
PubMed2001

[Cerebellar pilocytic astrocytomas in children. Report of 72 cases].

BACKGROUND AND PURPOSE: Cerebellar pilocytic astrocytoma (CPA) bears a well-deserved reputation of benignity. However, these tumors infiltrate the brainstem in a number of cases, and total removal may cause morbidity, whereas subtotal removal can lead to recurrence. MATERIAL AND METHODS: To define guidelines for tumor removal, management of tumor remnants and recurrence, we reviewed 72 cases of CPA of childhood operated on in our department since the introduction of CT. RESULTS: Surgical removal was total in 57 cases, had to be withheld because of brainstem infiltration in nine cases, and was revealed subtotal by postoperative imaging in six cases. Two of the latter were reoperated on; six had only radiological controls and did not progress. Early in the series, eight children had external irradiation because of subtotal removal or recurrence. Three children were reoperated on for tumor recurrence, between six and eight years after complete removal. We had no tumor-related mortality; long-term disability could be related to previous mental retardation, the severity of clinical state at presentation, and complications of surgery and irradiation. CONCLUSION: The goal of surgery is to cure the patient with minimal morbidity, however, total removal is not always possible. In our experience: i) tumor remnants can be surveyed radiologically, and reoperated only in case of progression; ii) the indications for radiotherapy should be the exception; iii) clinical and radiological follow-up should be protracted beyond entry into adulthood.

Adolescent↗
PubMed2001

[Video-assisted thoracoscopic surgery].

We describe our experience with video-assisted thoracoscopic surgery (VATS). Twenty-nine patients were operated on with this technique for various anterior thoracic spinal lesions. There were 6 cases of disc herniation with simple resection, 6 with acute thoracic fractures requiring anterior grafting and stabilization, 7 old fractures and malunions treated by corporectomy, grafting and anterior stabilization in 3, 4 with spinal metastases that were resected and stabilized, 3 with a paravertebral spinal tumor (2 schwannomas and 1 chondroblastoma), and 3 osteoid osteomas that were resected with anterior grafting in one case. Indications for these procedures are specified and the technical considerations discussed for each group of pathologies. We had three complications: one conversion to thoracotomy in a case of spinal metastasis, one pleural effusion, and one incomplete resection of a thoracic disc herniation. We emphasize the need for minimally invasive approaches in spinal surgery.

Adult↗
PubMed2000

[Suprasellar arachnoid cyst associated with syringomyelia. Case report].

We present a case of suprasellar arachnoid cyst which was revealed by visual impairement and hypopituitarism. Neuroradiological imaging showed the peculiar association of the suprasellar cyst with cerebellar tonsillar herniation and a large asymptomatic cervical syringomyelic cavity. Surgical treatment of the suprasellar cyst allowed the reduction of both the cyst and the syrinx. A common pathophysiological mechanism of these lesions is discussed. We suggest the possibility that an initial obstruction of the basal cisterns caused the suprasellar cyst formation which led to medullar cavity formation.

Arachnoid Cysts↗
PubMed1999

Intraventricular cavernomas: three cases and review of the literature.

OBJECTIVE AND IMPORTANCE: Cavernomas occur very rarely in the ventricular system. We report three cases of intraventricular cavernomas and review the literature. CLINICAL PRESENTATION: A 16-year-old female patient presented with a sudden distal deficit of the left superior limb. She had a voluminous tumor involving the two lateral ventricles, with radiological evidence of recent hemorrhage. A 30-year-old man presented with generalized seizures and a right hemiplegia related to a 4-cm-diameter cavernoma in the two lateral ventricles involving the interhemispheric scissure through the corpus callosum and left centrum ovale. The radiological appearance was not typical and did not allow the diagnosis. A 42-year-old man had a cavernoma in the third ventricle, which was responsible for his short-term memory loss. This cavernoma had been revealed by computed tomography that was performed after intracerebral hemorrhage related to another cavernoma in the right parietal lobe occurred. INTERVENTION: Stereotactic biopsies allowed the diagnosis of intraventricular cavernoma in the first case. Surgical removal via a right transcortical transventricular approach and a transcallosal approach in the first and second cases, respectively, was complete, resulting in good outcomes. Surgical removal via a right transcortical transventricular approach in the third case was partial. CONCLUSION: Intraventricular cavernomas are so uncommon that only 42 well-documented cases have been previously reported in the literature. It seems that their radiological diagnosis may be difficult because of their uncommon location in the ventricular system and their voluminous size. A wrong preoperative diagnosis has sometimes been the cause of inefficient therapy, such as radiotherapy, for these surgically curable benign lesions.

Adolescent↗
PubMed1997

Visuvalve software: an aid to the diagnosis of shunt failure.

Software designed to help the neurosurgeon in the diagnosis of shunt malfunction is presented. This software allows the possibility to record on a 3.5 diskette a patient's clinical information and four views of a CT scan performed when the patient was doing perfectly well with his shunt. This diskette, operated by MS-DOS on any IBM-compatible personal computer, can be read at any time, anywhere. The evaluation of the system demonstrated it was safe, with an excellent adhesion of the patients and of their families.

Cerebral Ventriculography↗
PubMed1997

[Value of a synthetic osseous model obtained by stereo-lithography for preoperative planning. Correction of a complex femoral deformity caused by fibrous dysplasia].

PURPOSE OF THE STUDY: The authors investigated the application of life-sized bone models obtained by stereolithography in orthopaedics. MATERIALS: The method was applied to planify correction of a severe femoral bone deformity secondary to fibrous dysplasia in a 27 years old man. This deformity was responsible for abnormal hip range of motion 70 degrees/-10 degrees (flexion-extension), -20 degrees/60 degrees (abduction-adduction), -30 degrees/60 degrees (external-internal rotation), and restricted walking ability because of lack of abduction and external rotation. A "shepherd-cross" deformity was identified on X-rays. A correction osteotomy was considered but we were unable to planify the angle of osteotomy on plain X-rays. CT scan identified 100 degrees of varus cervical deformity and 90 degrees of cervical antetorsion, but CT scan was helpless to choose the position for the osteosynthesis device. METHODS: 2D pictures obtained by CT scan were introduced and treated on a Silicon Graphics Indigo2 hardware. Mimics software authorized 2D and 3D views of bone which were separated of soft tissue by color separation process. CTM software authorized the 3D bone surface reconstruction (3D files). The 3D files were used to obtain life-sized bone model in 6 hours by stereolithographic process (scale 1/1). RESULTS: We planified a 70 degrees valgus and 40 degrees derotation and chose the best location for osteosynthesis device considering the fibrous dysplasia (best location was the posterior and superior aspect of the femoral neck). The planified osteotomy was performed and we obtained the stability of a nail-plate in the femoral neck. During surgery, we observed the bone model and the deformed femur had the same shape. Likewise, the model strongly indicated the inside bone structure (ie distribution of fibrous dysplasia tissue). Bone healing was obtained after 5 months with improvement of range of motion [(70/0) (20/30) (30/20)]. Histologic examination diagnosed fibrous dysplasia without malignancy features. CONCLUSION: Computer-generated life-sized bone models are available from computer tomographic data by means of stereolithographic process. This technic was helpful to improve planification of this complex proximal femoral osteotomy. Obtaining life-sized bone models could improve preoperative planning in case of multidirectional deformity, unusual site for osteotomy, or severe deformity impairing the choice for fixation device or its position into bone extremities. The indications for this method should be restricted to unusual and severe bone deformities, with inadequate preoperative assessment by standard X-rays or CT scans. Likewise, this method could be indicated for preoperative planning of technically demanding osteotomies such as oblique plane.

Adult↗
PubMed1996

Percutaneous vertebroplasty for osteolytic metastases and myeloma: effects of the percentage of lesion filling and the leakage of methyl methacrylate at clinical follow-up.

PURPOSE: To determine whether the percentage of vertebral lesion filling and the leakage of methyl methacrylate have any clinical significance at follow-up. MATERIALS AND METHODS: Forty percutaneous vertebroplasties were performed for metastases (30 cases) and myeloma (10 cases) in 37 patients. A computed tomographic scan was obtained 1-8 hours after methyl methacrylate injection and was used to assess the percentage of lesion filling by methyl methacrylate and the leakage of methyl methacrylate into the epidural tissues, neural foramina, intervertebral disks, venous plexus, and paravertebral tissue. The results were correlated with those obtained at clinical follow-up. RESULTS: Partial or complete pain relief was sustained in 36 of 37 patients. Pain relief was not proportional to the percentage of lesion filling. Clinical improvement was maintained in most patients. The 15 epidural leaks, eight intradiskal leaks, and two venous leaks of methyl methacrylate had no clinical importance. Two of eight foraminal leaks produced nerve root compression that required decompressive surgery. One of 21 paravertebral leaks produced transitory femoral neuropathy. CONCLUSION: Pain relief can occur despite insufficient lesion filling. In most patients, intradiskal and paravertebral leaks of cement had no clinical importance.

Bone Cements↗
PubMed1995

Carcinomatous meningitis in a case of anaplastic meningioma.

Malignant meningiomas are associated with a high rate of local recurrence, but seldom give remote metastases. Here, we report a case with carcinomatous meningitis occurring 13 months after treatment of the initial tumor. MRI showed no significant abnormalities. CSF contained abnormal cells, and electronic microscopy after cytocentrifugation confirmed their identity with the initial tumor.

Adult↗
PubMed1995

Intradural epidermoid cysts of the cerebellopontine angle: diagnosis and surgery.

We report on our recent experience with epidermoid cysts in the cerebellopontine angle. We operated on nine patients since 1985, seven of which were investigated with magnetic resonance imaging. Since the arrival of modern neuroimaging, large lesions can be found with only discrete symptoms, such as isolated tinnitus or unspecific headache. With computed tomography and magnetic resonance imaging, preoperative diagnosis was achieved for most patients; sometimes, however, epidermoid cysts may be very similar to arachnoid cysts. Surgery is the only possible treatment. The decision to operate should be carefully discussed for each patient, particularly if the patient is asymptomatic. The extent of the lesion at the anterior aspect of the brain stem, and sometimes above the tentorium cerebelli, fragile cortex, and vessels, and hazards of postoperative chemical meningitis often make such surgery difficult. The surgeon should not attempt total removal of the cyst membrane. Most patients who undergo surgery, however, recover well, with no or few sequelae. With a mean 3-year follow-up, no recurrence occurred, despite partial removal, as a result of the peculiarly slow growth of these lesions.

Adolescent↗