Biomedical subjects

D Rigamonti

Publications and source records attributed to D Rigamonti.

At least 55 records · Page 3Linked to original sources

PubMed1999

Mechanical behavior of a vein pouch saccular aneurysm model.

The response of an intracranial saccular aneurysm to applied loads, whether blood pressure or endovascular intervention, depends on both the geometry and material properties of the lesion. Yet, in the development of animal models of these lesions little attention has been given to the evaluation of their mechanical behavior. Our goal was to compare the multiaxial mechanical behavior of a canine vein pouch model to published data on veins and human aneurysms. Nine vein pouches were created surgically in six mongrel dogs by anastomosing a 2 cm segment of the external jugular vein to the common carotid artery in an end-to-side fashion. The lesions were harvested one week post-surgery and subjected to cyclic inflation tests using a custom system. Pressure-regional strain data revealed that vein pouch aneurysms are very extensible for pressures up to 30 mmHg, especially in the axial direction, but stiff thereafter. None of the lesions ruptured in vivo or during inflation tests. Based on these data, we conclude that the overall behavior of canine vein pouch lesions, at one week post-surgery, did not mimic well that of human aneurysms. Thus, there is a need to pursue modifications or other models for the purposes of clinically relevant studies of lesion growth, rupture, and treatment.

Animals↗

PubMed1999

Spinal epidural abscess: a review of epidemiology, diagnosis, and treatment.

Despite advances in neuroimaging and neurosurgical treatment, spinal epidural abscess (SEA) remains a challenging problem for the practicing physician. Early diagnosis is often elusive, and treatment is delayed. The optimal management of SEA is not clearly defined, and morbidity and mortality remain significant. In this review article, we discuss contemporary issues surrounding SEA. In addition, we shed light on the epidemiology of this potentially devastating disease and outline current diagnostic and therapeutic guidelines. We find the frequency of diagnosis of SEA is increasing. To prevent serious morbidity and mortality, early diagnosis and prompt treatment are essential. Patients who are at high risk for developing such abscesses should have an immediate magnetic resonance scan with contrast enhancement. Surgical drainage and prolonged antibiotic use are the cornerstones of treatment, although selected patients may be treated nonsurgically with very vigilant medical follow-up.

Abscess↗

PubMed1999

The natural history of cavernous malformations: a prospective study of 68 patients

OBJECTIVE: Cavernous malformations are angiographically occult cerebrovascular malformations found in approximately 0.5% of the population. To help further understand the natural history of these lesions, we prospectively followed 68 patients harboring cavernous malformations. METHODS: The 68 patients in this study were all diagnosed radiographically (67 patients) or surgically (1 patient) and were entered into a patient database. Age, sex, clinical symptoms, seizure frequency, focal neurological deficits, and presence or absence of extralesional hemorrhage were all recorded at presentation. Patients were then followed prospectively to determine the rate of hemorrhage and new-onset seizures. RESULTS: The mean follow-up per patient was 5.2 years, and the total follow-up was 352.9 patient-years. There was an average of 3.4 lesions per patient. Thirteen of the patients (19%) had familial cavernous malformations. Patients with familial disease were more likely to have multiple lesions than patients with sporadic disease (85% versus 25%, respectively [P = 0.001]). Initial presentation included headache (65%), seizures (49%), and focal neurological deficit (46%). Eleven symptomatic, radiologically proven, extralesional hemorrhages occurred during the 352.9 patient-years of follow-up for an overall hemorrhage rate of 3.1% per patient-year. Female patients had a significantly higher prospective hemorrhage rate (4.2% per patient-year versus 0.9% per patient-year [P = 0.04]). A history of hemorrhage at presentation was not a risk factor for subsequent hemorrhage during follow-up. The rate of new-onset seizures was 2.4% per patient-year. CONCLUSION: The clinical presentation and prospective hemorrhage rate reported here agree well with findings of other prospective studies. This information, combined with our new-onset seizure rate, should aid clinicians caring for patients with cavernous malformations.

Journal Article↗

PubMed1999

The natural history of cavernous malformations.

This article reviews general information about cavernous malformations, including histology, radiology, epidemiology, and symptomatology. Rates of hemorrhage as reported in the literature are presented. Familial cavernous malformations and their genetic basis are discussed. Finally, the variations in the biological behavior of cavernous malformations in different regions of the central nervous system are discussed and outcomes are assessed.

Brain Stem↗

PubMed1997

Brain capillary telangiectasia: MR imaging appearance and clinicohistopathologic findings.

PURPOSE: To demonstrate the clinical and magnetic resonance (MR) imaging findings of brain capillary telangiectasia and compare them with postmortem specimens. MATERIALS AND METHODS: MR images obtained in and clinical histories of 18 adult patients with a presumed diagnosis of capillary telangiectasia examined within 3 years were retrospectively reviewed. All patients had undergone MR imaging with conventional T1- and T2-weighted spin-echo sequences and gadolinium-enhanced T1-weighted and susceptibility-sensitive gradient-echo (GRE) sequences. No biopsies had been performed. Fourteen patients had undergone clinical and MR imaging follow-up (median, 11 months). Postmortem tissues from three cases of histopathologically confirmed capillary telangiectasia were imaged. RESULTS: All lesions were small, homogeneously enhancing, and hypo- to isointense on T1-weighted images and iso- to slightly hyperintense on proton-density- and T2-weighted images. None was hypointense on proton-density- or T2-weighted images. All lesions showed marked GRE signal loss. None had changed at follow-up. Two patients had multiple classic cerebral cavernous angiomas. The three specimens showed no abnormal susceptibility and contained no hemosiderin at tissue analysis. CONCLUSION: Capillary telangiectasia has mild contrast material enhancement but is otherwise undetectable on conventional MR images. It lacks the "hemosiderin rim" of cavernous angioma and demonstrates increased susceptibility only on GRE images, likely owing to blood oxygen-level-dependent contrast. GRE is essential in diagnosing brain capillary telangiectasia, which could otherwise be misdiagnosed as neoplasia, subacute infarction, or demyelination.

Brain↗

PubMed1997

Linkage of the locus for cerebral cavernous hemangiomas to human chromosome 7q in four families of Mexican-American descent.

OBJECTIVE: To determine with greater precision the map location of the locus associated with familial cavernous hemangiomas. BACKGROUND: Cavernous malformations of the brain are a significant cause of seizures, progressive or apoplectic neurologic deficit, and headache. Prevalence estimates from autopsy series vary from 0.39 to 0.9%. This disorder (OMIM #116860) can be inherited as an autosomal dominant trait with variable penetrance. Linkage to markers on the long arm of chromosome 7 was recently reported in separate reports in three apparently unrelated Hispanic kindreds as well as in two kindreds of non-Hispanic descent. DESIGN/METHODS: We examined clinically, by MRI scanning, and by pathologic examination of surgical specimens, members of four large Mexican-American families segregating cavernous hemangiomas of the brain. Linkage analysis was performed with use of blood specimens from morphologically proven cases. Two-point linkage analysis was performed with the MLINK program of the LINKAGE package. Multipoint analysis was performed between two markers and the disease locus with LINKMAP in the FASTLINKAGE package. Allele frequencies were set as described by the Genome Database (GDB). Maximum penetrance for the disease allele was set to 0.75. RESULTS: The highest lod score was observed for marker D7S652 with Zmax = 6.66 at theta(max) = 0.00. Multipoint LOD score analysis placed the disease locus in the 11 cM interval between markers D7S630 and D7S527 with Zmax = 9.19. Haplotype analysis is in agreement with the placement of the disease gene between D7S630 and D7S527 and further shows a minimal shared region within this interval, indicating a founder effect in the establishment of the mutation in these families. CONCLUSIONS: We confirmed the linkage of cavernous hemangioma to markers on the long arm of chromosome 7q, and the estimate of the map location has been refined to a region of shared haplotype between markers D7S630 and D7S527 in four Mexican-American families who may be descended from a common ancestor in Sonora County, Mexico.

Adolescent↗

PubMed1996

Radiosurgery for cerebral arteriovenous malformations: assessment of early phase magnetic resonance imaging and significance of gadolinium-DTPA enhancement.

PURPOSE: To evaluate the initial changes within the nidus of arteriovenous malformations (AVMs) and to assess the reaction to the brain tissue surrounding AVMs after radiosurgery by serial magnetic resonance (MR) imaging. METHODS AND MATERIALS: Twenty-one patients, treated using 60Co gamma knife unit with cerebral AVMs, were retrospectively evaluated. Forty-seven follow-up MR images of the 21 patients were performed including 10 patients with two or more serial gadolinium enhanced studies (Gd-MR). Two or more sequential MR angiographies (MRA) were obtained in 13 patients. Three-dimensional (3D) time-of-flight MRA and two-dimensional (2D) phase contrast MRA were used in 13 patients for evaluating the flow changes of AVMs. The follow-up period after radiosurgery ranged from 3 to 30 months (average 10.8 months) and the interval time of MRI ranged from 34 days to 13 months (average 4.9 months). RESULTS: Reduction of nidus size was observed in 14 of 21 patients (67%) between 4 to 13 months on spin echo (SE) images. Complete obliteration was observed on SE images in 4 of these 14 patients; three were confirmed by conventional angiography. New hyperintense areas surrounding the nidus on T2s-weighted images (T2WI) developed in 9 of the 14 patients who showed nidus reduction between 5 to 17 months after radiosurgery; in three patients, size of the hyperintense area started to decrease between 6 to 7 months after its appearance. Probable radiation necrosis of pons developed in one patient 26 months after radiosurgery. The irradiated area within the AVM nidus was significantly enhanced in 8 of the 10 patients who underwent Gd-MR. The degrees of enhancement within the nidus increased with time in 7 of the 10 patients. Overall, total enhancement of irradiated areas was observed in four of the 10 patients; in three of the four, the enhancement decreased in size and degree, indicating nidus reduction. In three patients who had a partial volume irradiation within the nidus, the enhancing areas corresponded with the exact portions of irradiated volume. The nidus reduction was observed in 7 of the 13 patients on MRA during 5 to 13 months after radiosurgery. MRA was more useful compared to SE images in four of the seven patients in evaluating the size change of AVM nidus, feeding arteries, and draining veins. CONCLUSION: Magnetic resonance imaging and MRA were useful in assessing the progress of nidus reduction. T2-weighted imaging was sensitive to radiation-induced reaction in and around the AVM nidus. The enhancement within the AVM nidus on Gd-MR may represent the initial sign of nidus reduction and demonstrates the exact location of irradiation in the nidus. The changes of the enhancement pattern are presumed to represent the processes of nidus reduction and irradiated reaction within the AVM nidus.

Adolescent↗

PubMed1996

Detection of intracranial internal carotid artery and middle cerebral artery vasospasm following subarachnoid hemorrhage.

Little is known about the accuracy of transcranial Doppler (TCD) sonography in detecting intracranial internal carotid artery (IICA) and middle cerebral artery (MCA) vasospasm. TCD was performed in 49 patients with subarachnoid hemorrhage to evaluate 90 IICAs and 87 MCAs during the vasospasm period. When a mean velocity of at least 90 cm/sec was used to indicate IICA vasospasm, there were 11 positive, 42 negative, 4 false-positive, and 33 false-negative results. Sensitivity was 25% and specificity was 93%. When a mean velocity of at least 120 cm/sec was used to indicate MCA vasospasm, there were 15 positive, 45 negative, 3 false-positive, and 24 false-negative results (15 operator errors). Sensitivity was 38.5% and specificity was 93.7%. When the diagnostic criterion was changed to at least 130 cm/sec, specificities were 100% (IICA) and 96% (MCA) and positive predictive values were 100% (IICA) and 87% (MCA). The authors conclude that TCD accurately detects IICA and MCA vasospasm when flow velocities are at least 130 cm/sec. However, its sensitivity may be underestimated and the importance of operator error, overestimated.

Adult↗

PubMed1996

Detection of vasospasm by transcranial Doppler sonography. The challenges of the anterior and posterior cerebral arteries.

Little information exists on the utility of transcranial Doppler sonography (TCD) in detecting anterior (ACA) and posterior cerebral artery (PCA) vasospasm following subarachnoid hemorrhage. During the period at risk for vasospasm, 53 patients with subarachnoid hemorrhage who had technically adequate TCD performed within 24 hours of cerebral angiography, allowing evaluation of 87 ACAs and 84 PCAs, were studied. ACA and PCA vasospasm were defined by mean blood flow velocities of at least 120 cm/sec and at least 90 cm/sec, respectively. For detection of ACA vasospasm, sensitivity was 18% and specificity was 65%. For PCA vasospasm, sensitivity was 48% and specificity was 69%. False-positive findings for occlusion accounted for 12 (92%) of 13 ACA of false-positive results and 7 (37%) of 19 PCA false-positive results, and were most often due to anatomical factors and operator error or inexperience. After exclusion of both true-positive and false-positive findings for occlusion and changes in the diagnostic criterion to at least 130 cm/sec for ACA vasospasm and at least 110 cm/sec for PCA vasospasm, specificity improved for both types of vasospasms (100 and 93%, respectively). However, the sensitivity of TCD to detect ACA and PCA vasospasm is limited by a variety of anatomical, technical, and other factors. It is concluded that TCD is highly specific in detecting both ACA and PCA vasospasm on arteries that can be insonated.

Adult↗

PubMed1995

The significance of dorsal migration of the cord after extensive cervical laminectomy for patients with traumatic central cord syndrome.

Central cord syndrome (CCS) resulting from traumatic cervical injury is often associated with cervical stenosis and/or spondylosis. The efficacy of multilevel laminectomy in the treatment of this condition has been controversial. The objective of this study was to validate by magnetic resonance (MR) imaging the occurrence of dorsal cord migration after extensive laminectomy for patients with the clinical syndrome of central cord damage and its relationship to the short-term outcome. During a 28-month period, the authors evaluated 20 patients (mean age 54 years) who sustained CCS after cervical spine trauma. Pre- and postoperative MR imaging assessed the adequacy of cervical cord decompression by multilevel laminectomy. All patients had cervical canal stenosis with complete obliteration of the anterior subarachnoid space over multiple levels. Seventeen patients initially had CCS of different degrees of severity. One had no motor deficit and two had motor complete with sensory deficits greater in their arms. Laminectomy, generally from C2 to C7 without facetectomy, was performed after plateau of neurological recovery (mean 17 days postinjury). Neurological assessment 3 months after operation revealed improvement in 12, stable function in 7, and progression of deficit in one with no mortality. The postoperative midsagittal MR images demonstrated adequate decompression with restoration of anterior cerebrospinal fluid space and posterior cord migration in 12 patients (60% of the 20), but only 8 of them also had improved function. MR imaging demonstrated that, in the presence of multilevel spondylosis/stenosis, laminectomy may provide adequate spinal cord decompression in patients with traumatic CCS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Spinal epidural abscess with gadolinium-enhanced MRI: serial follow-up studies and clinical correlations.

We reviewed serial MRI with and without gadolinium-DTPA in eight patients with spinal epidural abscess and correlated the findings and the clinical manifestations. In four patients, diffuse abscesses spanned four vertebral bodies or more; the others had focal abscesses associated with osteomyelitis and/or diskitis. In three of the four patients with diffuse abscesses, MRI (NCMRI) showed diffuse encasement of the subarachnoid space. Contrast-enhanced MRI (CEMRI) demonstrated linear enhancement surrounding unenhanced pus. In the four patients with focal abscesses, CEMR delineated the inflammatory process more clearly than NCMR. On follow-up studies, decrease in abscess size and better visualization of the subarachnoid space correlated with clinical improvement in both diffuse and focal abscesses. Despite clinical improvement, contrast enhancement persisted in the disk or epidural space of three patients, and was thought to represent chronic granulomatous change or postsurgical scar. CEMR is very valuable for the initial diagnosis of an epidural abscess, particularly if it involves lengthy segments. During follow-up, CEMR can document responses to therapy, and provide information for determining appropriate treatment.

Abscess↗

PubMed1994

Dolichoectatic aneurysm of common carotid artery: an animal model with histological correlation.

There is a limited understanding of the pathogenesis of dolichoectatic (dolicho = long; ectatic = dilated) aneurysms of elastic arteries. Therefore, we developed a model of dolichoectatic changes in elastic arteries by injecting porcine elastase into the media of the carotid artery of male New Zealand white rabbits. After 3 months, gross examination of the carotid arteries in vivo revealed dilated and tortuous vessels. The carotid arteries were then harvested, and cross-sections of the vessels were stained by the Verhoff-van Giesson stain. Histologically, the internal elastic lamina was dissolved in the most dilated areas. The elastic lamellae of the media were also digested and there was reorientation of the innermost medial smooth muscle layer. These gross and histologic changes were present in 80% of the treated carotid arteries and in none of the contralateral control vessels. Our study suggests the importance of the elastic lamellae for the maintenance of tubular shape and length of the carotid artery and describes a new chronic animal model of dolichoectatic aneurysm of the common carotid artery.

Aneurysm↗

PubMed1994

Transcranial Doppler detection of vertebrobasilar vasospasm following subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Transcranial Doppler sonography is of established value in the detection and monitoring of middle cerebral artery vasospasm. Little information exists on the utility of transcranial Doppler for detection of posterior circulation vasospasm. METHODS: Cerebral angiography and conventional hand-held transcranial Doppler sonography were compared to determine sensitivity and specificity of transcranial Doppler for detection of vertebral and basilar artery vasospasm. RESULTS: Of 59 consecutive subarachnoid hemorrhage patients with transcranial Doppler angiogram correlations, 42 underwent posterior circulation angiography to evaluate 64 vertebral arteries and 42 basilar arteries during the period of risk for vasospasm and had technically adequate transcranial Doppler examinations within 24 hours of the angiogram. A mean flow velocity of 60 cm/s and above was indicative of both vertebral and basilar artery vasospasm. For the vertebral artery, there were 7 true-positive test results, 42 true-negatives, 6 false-positives (unknown cause in 3, increased collateral flow in 1, adjacent vessel vasospasm in 1, hyperperfusion in 1), and 9 false-negatives (anatomic in 7, operator error in 2). Sensitivity was 44% and specificity was 87.5%. For the basilar artery, there were 10 true-positives, 23 true-negatives, 6 false-positives (unknown cause in 4, hyperemia/hyperperfusion in 1, increased collateral flow in 1), and 3 false-negatives (operator error in 2, tortuous vessel course in 1). Sensitivity was 76.9% and specificity was 79.3%. When the diagnostic criterion was changed to > or = 80 cm/s (vertebral artery) and > or = 95 cm/s (basilar artery), all false-positive results were eliminated (specificity and positive predictive value, 100%). CONCLUSIONS: Our data suggest that transcranial Doppler has good specificity for the detection of vertebral artery vasospasm and good sensitivity and specificity for the detection of basilar artery vasospasm. Transcranial Doppler is highly specific (100%) for vertebral and basilar artery vasospasm when flow velocities are > or = 80 and > or = 95 cm/s, respectively.

Adult↗

PubMed1994

The natural history of familial cavernous malformations: results of an ongoing study.

Cavernous malformations are congenital abnormalities of the cerebral vessels that affect 0.5% to 0.7% of the population. They occur in two forms: a sporadic form characterized by isolated lesions, and a familial form characterized by multiple lesions with an autosomal dominant mode of inheritance. The management of patients with cavernous malformations, particularly those with the familial form of the disease, remains a challenge because little is known regarding the natural history. The authors report the results of an ongoing study in which six families afflicted by familial cavernous malformations have been prospectively followed with serial interviews, physical examinations, and magnetic resonance (MR) imaging at 6- to 12-month intervals. A total of 59 members of these six families were screened for protocol enrollment; 31 (53%) had MR evidence of familial cavernous malformations. Nineteen (61%) of these 31 patients were symptomatic, with seizures in 12 (39%), recurrent headaches in 16 (52%), focal sensory/motor deficits in three (10%), and visual field deficits in two (6%). Twenty-one of these 31 patients underwent at least two serial clinical and MR imaging examinations. A total of 128 individual cavernous malformations (mean 6.5 +/- 3.8 lesions/patient) were identified and followed radiographically. During a mean follow-up period of 2.2 years (range 1 to 5.5 years), serial MR images demonstrated 17 new lesions in six (29%) of the 21 patients; 13 lesions (10%) showed changes in signal characteristics, and five lesions (3.9%) changed significantly in size. The incidence of symptomatic hemorrhage was 1.1% per lesion per year. The results of this study demonstrate that the familial form of cavernous malformations is a dynamic disease; serial MR images revealed changes in the number, size, and imaging characteristics of lesions consistent with acute or resolving hemorrhage. It is believed that the de novo development of new lesions in this disease has not been previously reported. These findings suggest that patients with familial cavernous malformations require careful follow-up monitoring, and that significant changes in neurological symptoms warrant repeat MR imaging. Surgery should be considered only for lesions that produce repetitive or progressive symptoms. Prophylactic resection of asymptomatic lesions does not appear to be indicated.

Adolescent↗

PubMed1994

Fourth ventricular hemangioblastoma associated with pheochromocytoma and renal medullary fibroma.

Intraventricular hemangioblastomas are exceptionally rare. Of the cases described in the literature, very few were associated with von Hippel-Lindau disease. We present a highly unusual case of a fourth ventricular hemangioblastoma associated with a pheochromocytoma and a renal medullary fibroma. This may represent a forme fruste of the von Hippel-Lindau complex. A workup for papilledema resulted in the discovery of this rare finding.

Adrenal Gland Neoplasms↗

PubMed1994

Thoracic epidural abscess.

Twenty-one cases of thoracic spinal epidural abscess occurring over a 10-year period were retrospectively reviewed. Diagnosis was made by MRI or myelography and confirmed in the operative cases. A bacterial agent was isolated in 18 of the cases (86%). When measured, the erythrocyte sedimentation rate was elevated in all cases. Four patients who presented without neurologic deficits remained intact. All patients who presented with neurological deficits underwent surgical intervention in addition to intravenous antibiotics. Of the 15 patients who presented with a paraparesis of less than antigravity strength, five eventually were independent ambulators and continent. A good outcome resulted in 80% of those who underwent decompression within 24 h, as opposed to only 10% of the patients decompressed after 24 h. Good results can be obtained despite severe neurologic compromise when treated by rapid diagnosis and decompression of the spinal canal.

Abscess↗

PubMed1994

Epidural abscess in the cervical spine.

A ten-year retrospective review of 23 cases of documented spinal epidural abscess in the cervical spine was undertaken to define the clinical features and establish current diagnostic and therapeutic criteria. Diagnosis was made by magnetic resonance imaging or myelography. Risk factors included intravenous drug abuse, diabetes mellitus, previous trauma, and a positive serologic test for the human immunodeficiency virus. A bacterial agent was isolated in 21 cases (91%). Neurologic deficits were present in 20 of the cases (87%) at the time of diagnosis. Erythrocyte sedimentation rate was elevated in all patients in whom it was measured. All patients were treated with appropriate antibiotics, usually for 6 to 8 weeks. Twenty-one patients underwent operative procedures using percutaneous aspiration (1 patient), the anterior approach (14 patients) or the posterior approach (4 patients), or a combination of the two approaches (2 patients). Four of ten patients who initially had less than antigravity strength were eventually ambulatory and continent; in each case, operative decompression was performed within 36 hours of initial consultation. Three patients who had no initial neurologic deficits remained intact.

Abscess↗

PubMed1993

Spinal epidural abscess: evaluation with gadolinium-enhanced MR imaging.

Magnetic resonance (MR) imaging with gadopentetate dimeglumine was performed in 25 patients with spinal epidural abscess (SEA). Seventeen of 25 patients underwent follow-up MR imaging. The studies were retrospectively reviewed. In 20 patients, diskitis was the primary infectious foci; however, five patients developed diffuse SEA without diskitis. The two most common MR appearances were (a) homogeneous or heterogeneous enhancement of the solid portion of the SEA and (b) thin or thick enhancement around the liquefied collections of pus. Dural enhancement was frequently seen in patients with lengthy vertebral involvement of SEA. Engorgement of the epidural venous plexus or basivertebral veins was occasionally observed. The changes in abscess size noted on follow-up studies correlated well with clinical improvement or deterioration in most patients. Persistent contrast enhancement, however, was frequently noted at the site of diskitis, osteomyelitis, or surgical drainage sites despite clinical improvement. Careful correlation of MR imaging findings with clinical findings and laboratory data is important in predicting prognosis for these patients.

Abscess↗