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Biomedical subjects

D W Chakeres

Publications and source records attributed to D W Chakeres.

At least 19 recordsLinked to original sources
PubMed2001

Functional MRI evidence of cortical reorganization in upper-limb stroke hemiplegia treated with constraint-induced movement therapy.

OBJECTIVE: The purpose of this pilot study was to test constraint-induced movement therapy for chronic upper-limb stroke hemiparesis and to investigate the neural correlates of recovery with functional magnetic resonance imaging (MRI) in two subjects. Both subjects had been discharged from traditional therapy because no further improvement was anticipated. DESIGN: Constraint-induced movement therapy consisted of 6 hr of daily upper-limb training for 2 wk; a restrictive mitt was worn on the nonparetic limb during waking hours. Functional MRI was performed on a 1.5-T MRI with echo-planar imaging; at the same time, the subjects attempted sequential finger-tapping. RESULTS: Compared with baseline, performance time improved an average of 24% immediately after training and also continued to improve up to 33% 3 mo after training. Lift, grip strength, and Motor Activity Log scores likewise improved. Initially, on functional MRI, subject 1 activated scattered regions in the ipsilateral posterior parietal and occipital cortices. Subject 2 showed almost no areas of significant activation. After training, subject 1 showed activity bordering the lesion, bilateral activation in the association motor cortices, and ipsilateral activation in the primary motor cortex. Subject 2 showed activation near the lesion site. CONCLUSION: Constraint-induced movement therapy produced significant functional improvement and resulted in plasticity as demonstrated by functional MRI.

Exercise Therapy↗
PubMed2000

Tumor growth and audiometric change in vestibular schwannomas managed conservatively.

OBJECTIVE: To prospectively define the correlation between changes in tumor volume and audiometric function in vestibular schwannomas managed conservatively. STUDY DESIGN: Prospective longitudinal study. METHODS: Twenty-one patients (age range, 15-84 y; mean age, 63.3 y) with newly diagnosed vestibular schwannomas were enrolled between 1994 and 1999 in a protocol at The Ohio State University Hospital (Columbus, OH) to evaluate the correlation between tumor volume and audiometric change during a period of observation. Patients were evaluated yearly by clinical examination, a standardized internal auditory canal magnetic resonance imaging scan with gadolinium contrast for volumetric analysis, and audiometric function testing. Demographic data, historical features, neurofibromatosis type 2 (NF2) status, initial testing results, and serial testing results were recorded. RESULTS: An increase in tumor volume occurred in 14 of the 21 patients (66%). The pattern of volumetric change was found to be extremely variable. Multiple regression analysis revealed significant correlations of changes in tumor volume with changes in pure-tone average and speech discrimination score (P < .0001 and P = .0021, respectively). Change in tumor volume had greater effect on pure-tone average and speech discrimination score in patients initially with class D audiometric function when compared with those initially in class A (P = .0083 and P = .0245, respectively). The presence of NF2 had an independent protective effect against deterioration of the pure-tone average when compared with patients without NF2 (P = .0125). CONCLUSIONS: This study demonstrated a significant correlation between a change in volume and auditory deterioration in vestibular schwannomas being managed with a trial of observation. A given change in tumor volume appeared to have a greater effect on pure-tone average and speech discrimination score as initial auditory classification declined.

Adolescent↗
PubMed1999

Brain tumors: complications of cerebral angiography accompanied by intraarterial chemotherapy.

PURPOSE: To evaluate the rate of complications associated with diagnostic cerebral angiography accompanied by intraarterial chemotherapy for the treatment of primary and metastatic brain tumors. MATERIALS AND METHODS: Three hundred ninety-two consecutive transfemoral cerebral angiographic procedures accompanied by intraarterial chemotherapy were performed in 48 patients (28 men, 20 women), and complications were evaluated. RESULTS: The most common local complications were groin hematomas, which occurred in 10 (2.6%) of the 392 procedures and none of which required therapy. Two carotid arterial dissections (0.5%) were reported in two patients who were asymptomatic and did not require further treatment. Both improved at follow-up examinations. Only one patient required surgery for a delayed popliteal embolus. Systemic transient complications occurred five times (1.3%). There were seven (1.8%) transient neurologic events, which were paresis and visual disturbances. Six (1.5%) transient seizure events were recorded. There were no permanent neurologic complications. CONCLUSION: Intraarterial chemotherapy for brain tumors is a safe procedure with a low complication rate.

Adolescent↗
PubMed1999

Assessment of internal auditory canal tumors: a comparison of contrast-enhanced T1-weighted and steady-state T2-weighted gradient-echo MR imaging.

BACKGROUND AND PURPOSE: Although contrast-enhanced T1-weighted MR imaging is the standard of reference for diagnosing tumor in the cerebellopontine angle, high-resolution T2-weighted imaging may show more details of the seventh and eighth cranial nerve branches, resulting in more accurate tumor volume measurements. The purpose of this study was to compare two MR sequences for their ability to delineate internal auditory canal tumors. METHODS: Twenty-seven ears in 21 patients with 16 confirmed schwannomas were studied with the 3D T2-weighted prototype segment-interleaved motion-compensated acquisition in steady state (SIMCAST) and the T1-weighted contrast-enhanced spoiled gradient-echo (SPGR) techniques. Twenty-eight axial sections were acquired using parameters of 17/3.3 (TR/TE), a 40 degrees flip angle, a 20 x 15-cm or 22 x 16-cm field of view (FOV), a 512 x 256 matrix, and a 0.4- or 1.2-mm section thickness for the SIMCAST technique, and 30/4.2, a 30 degrees flip angle, a 20 x 20-cm FOV, a 512 x 288 matrix, and a 1.5-mm section thickness for the SPGR technique. Tumor appearance and depiction of surrounding anatomy, including the cranial nerves, were evaluated. Tumor volumes were measured by manual tracing. RESULTS: Both sequences clearly identified tumors that ranged in size from 0.06 to 3.0 cm3. Measurements on both sequences agreed, on average, within 14%. The information from both sequences was complementary. SIMCAST usually delineated the CSF spaces better, whereas SPGR more clearly showed the tumor/brain boundary. CONCLUSION: SIMCAST and SPGR are suitable for tumor detection and volume measurements. SPGR has somewhat better contrast, but SIMCAST excels at depicting the surrounding anatomy and tumor involvement of the seventh and eighth cranial nerves.

Adolescent↗
PubMed1998

High-resolution MR imaging of the auditory pathway.

MR imaging is a valuable tool in the evaluation of the auditory pathway. The current techniques in high-resolution MR imaging of the temporal bone are presented followed by a review of normal anatomy. Several diseases involving the middle ear, inner ear, internal auditory canal, and cerebellopontine angle are then presented. A radiologic-pathologic approach is used to illustrate the nature of these diseases and their appearance on MR imaging.

Auditory Diseases, Central↗
PubMed1997

Assessment of the lingual nerve in the third molar region using magnetic resonance imaging.

PURPOSE: The purpose of this study was to determine the precise in situ location of the lingual nerve in the third molar region using high-resolution magnetic resonance imaging. PATIENTS AND METHODS: Ten healthy volunteers (20 sides) with mandibular third molars underwent bilateral axial and coronal high-resolution magnetic resonance imaging (MRI) examinations of the posterior mandible and floor of the mouth from the lingula to the mental foramen. Three trained individuals made measurements of each image to determine the vertical and horizontal position of the lingual nerve in the third molar region. RESULTS: The mean vertical (2.75 +/- 0.97 mm [range, 1.52-4.61]) and horizontal (2.53 +/- 0.67 mm [range, 0.00-4.35]) distances to the lingual crest and lingual plate of the mandible were determined. In the third molar region, there were only 2 of 20 cases (10%) in which the nerve was above the lingual crest, and there were 5 of 20 instances (25%) in which the nerve was in direct contact with the lingual plate. CONCLUSIONS: This study precisely documents the in situ location of the lingual nerve in the third molar region, and reconfirms the relative vulnerable position of this structure during third molar surgery.

Adult↗
PubMed1996

Submillimeter magnetic resonance imaging of the temporal bone in Meniere's disease.

The pathoetiology of Meniere's disease remains elusive. Histopathologic and imaging studies have implicated congenital or developmental abnormality of the endolymphatic duct as a likely predisposing factor to the development of endolymphatic hydrops and clinical Meniere's disease. Recently, improved high-resolution magnetic resonance imaging (MRI) protocols have allowed better demonstration of the soft tissues of the endolymphatic duct and sac. This study is a prospective evaluation of the ability of submillimeter MRI to detect the endolymphatic duct in Meniere's disease patients and control subjects. In addition, the development of the temporal bone in the region of the endolymphatic sac and duct is evaluated by measurements of the distance from the posterior semicircular canal to the subarachnoid space and the distance from the vestibule to the subarachnoid space. Visualization of the endolymphatic duct was found to be significantly less frequent in the Meniere's disease patients (29%) than in the control subjects (91%). Temporal bone measurements in the region of the endolymphatic duct showed patients with Meniere's disease to have smaller dimensions than control subjects.

Adult↗
PubMed1996

Submillimeter-resolution MR of the endolymphatic sac in healthy subjects and patients with Menière disease.

PURPOSE: To evaluate the utility of submillimeter resolution MR imaging for direct depiction of functional soft-tissue components of the intraosseous endolymphatic duct and sac in healthy subjects and in patients with Menière disease. METHODS: Axial MR images were acquired of 14 patients with Menière disease and 14 healthy volunteers at 1.5 T with a short-echo-time steady-state 3-D gradient-echo sequence. Seven volunteers and eight patients were also studied with a T1-weighted 3-D spoiled gradient-echo sequence. T1/T2 relaxation times were estimated from studies with multiple flip angles. RESULTS: Independent of the acquisition method, intraosseous endolymphatic ducts and sacs were seen unambiguously in the ears of 20 of 21 healthy subjects but in only four of 12 asymptomatic and two of 10 symptomatic ears of patients with Menière disease. Other labyrinthine structures were well depicted in all subjects. Furthermore, shorter relaxation times were measured for the contents of the vestibular aqueduct than for other labyrinthine structures. CONCLUSION: In our high-resolution study, the intraosseous portions of the endolymphatic ducts and sacs were depicted in most of the healthy subjects. They were frequently not seen in either ear of patients with unilateral Menière disease, presumably because of their small size.

Adult↗
PubMed1995

Reformatted planar 'Christmas tree' MR appearance of the endolymphatic sac.

A high-resolution three-dimensional Fourier transform technique and prototype bilateral dual phased-array surface coil technique was used to make inner ear structures visible on MR. Multiplanar reformatted images, parallel to the plane of the vestibular aqueduct, allowed viewing of the entire endolymphatic sac/vestibular aqueduct on one section, producing a "Christmas tree" shape. The reformation was obtained using a double oblique angle, 45 degrees from true sagittal and 70 degrees from the orbital-meatal axis.

Adolescent↗
PubMed1993

Fibrosing pseudotumor of the sella and parasellar area producing hypopituitarism and multiple cranial nerve palsies.

We present an unusual patient with a medical history of a fibrosing pseudotumor of the left orbit that had been stable for 8 years who presented with acute anterior hypophyseal failure. During the next 10-month period, sequential magnetic resonance scans showed a rapid growth of a plaque-like sellar and parasellar mass extending into the right cavernous sinus, right Meckel's cave, along the dural surfaces of the clivus, dens, and body of the second cervical vertebra. A transsphenoidal biopsy revealed sphenoid and intrasellar pseudotumor that invaded the adenohypophysis and had microscopic features identical to those of the previously excised orbital pseudotumor. Rapid growth of the pseudotumor continued despite a course of radiotherapy. Palsies of cranial nerves V and VI and of the sensory root of the cranial nerve VII developed on the right side. Steroid therapy was associated with improvement of the cranial nerve palsies. This is the first report of the sellar fibrosing pseudotumor producing not only anterior hypophyseal failure, but also cranial nerve dysfunction secondary to plaque-like extension into the cavernous sinus, Meckel's cave, and cranial base dura. This intracranial plaque-like extension of a fibrous pseudotumor corresponds to a hypertrophic intracranial pachymeningitis, which is a rare, previously described phenomenon associated to the syndrome of multifocal fibrosclerosis.

Biopsy↗
PubMed1992

Magnetic resonance imaging of trauma to the thoracic and lumbar spine. The importance of the posterior longitudinal ligament.

Magnetic resonance imaging was used to evaluate 24 patients with injuries to the thoracic, thoracolumbar (T12-L1), or lumbar spine. Correlation of the magnetic resonance imaging findings to surgical therapy and outcome was evaluated, with particular attention to the longitudinal ligaments. The ability of the magnetic resonance imaging to detect the extent of trauma to the spinal cord parenchyma and to the anterior and posterior longitudinal ligaments was found to be important in guiding the surgical approach to these spine fractures.

Adolescent↗
PubMed1992

Magnetic resonance imaging correlates of neuropsychological impairment in multiple sclerosis.

The authors examined whether specific neuropsychological abnormalities in multiple sclerosis (MS) are associated with focal lesion areas detected by MRI. Lesion area, regardless of distribution, correlated with performance on the vast majority of neuropsychological procedures. No significant difference appeared between groups with normal/mild and moderate overall cognitive impairment on any of the MRI measures. However, patients with severe cognitive impairment had greater lesion area, regardless of location, and had significant atrophy of the corpus callosum compared with the other two groups. These results suggest that severe atrophy of the corpus callosum reflects global disease and provides a relatively focal morphological marker of severe cognitive impairment in MS.

Adult↗
PubMed1991

Cerebellorubral degeneration after resection of cerebellar dentate nucleus neoplasms: evaluation with MR imaging.

The authors describe the magnetic resonance (MR) findings in seven patients who developed severe cerebellar symptoms and atrophy of the contralateral red nucleus following removal of unilateral neoplasms in the deep nuclei of the cerebellum. For most patients, pre- and postoperative spin-echo MR images were obtained with long repetition times (TRs) at 1.5 T. The long TR images obtained before surgery demonstrated unilateral masses involving the dentate nucleus. Long TR images obtained after surgical resection of the dentate nucleus showed increased signal intensity in all of seven contralateral red nuclei, three of seven ipsilateral superior cerebellar peduncles, and two of seven contralateral inferior olivary nuclei. Three other patients who underwent surgery for cerebellar neoplasms without resection of the dentate nuclei showed no postoperative brain stem changes on MR images. The authors speculate that the changes in the contralateral red nuclei are due to cerebellorubral degeneration (since well-described neural tracts interconnect the dentate nucleus and the contralateral red nucleus). Injury of the dentate nucleus may result in degeneration of distant neural connections.

Adolescent↗
PubMed1991

Normal venous anatomy of the brain: demonstration with gadopentetate dimeglumine in enhanced 3-D MR angiography.

This investigation evaluates whether gadopentetate dimeglumine enhancement of three-dimensional (3-D) acquisition MR angiography can generate clinically useful images of the normal venous anatomy of the brain. 3-D MR angiography of normal cerebral arterial anatomy has made rapid progress, although demonstration of detailed venous anatomy with similar techniques has been much less revealing. To overcome the limitation of slow venous flow, IV gadopentetate dimeglumine contrast enhancement was used to alter the relaxation times of blood, thus augmenting the venous signal. Several groups of patients were evaluated: we studied eight patients both with and without contrast enhancement, 20 patients and volunteers with multiple techniques to determine optimal technical parameters, and seven patients in whom enhanced MR studies were compared with standard selective biplane cut-film arterial angiograms. Only the large dural sinuses (such as the transverse sinus) could be seen on unenhanced studies owing to the saturation of slowly flowing venous spins. With contrast enhancement, many of the important small and large cerebral venous structures were routinely seen with reasonable scanning times (7 min). The venous anatomy was well seen for approximately one-half hour after injection and correlated well with angiograms. There are several important limitations to this technique, including a limited field of view, variable visibility of specific veins owing to technical and physiologic factors, confusion of enhancing non-flow-related structures, and lack of detailed physiologic information. Single excitation 3-D MR angiograms are insensitive in the evaluation of cerebral venous structures. Enhancement with gadopentetate dimeglumine affords rapid scanning and excellent visualization of the pertinent venous anatomy. The best image quality was obtained with a sequence of 50/7/30 degrees (TR/TE/flip angle).

Adolescent↗
PubMed1990

Magnetic resonance imaging in Parkinson's disease.

Magnetic resonance imaging was utilized to examine changes in the pars compacta associated with Parkinson's disease. We found a reduction in average width of the pars compacta in advanced- but not early-stage patients. Conversely, a significant difference in width (right minus left) was observed in early- but not late-stage patients. Width asymmetry may be a sensitive magnetic resonance imaging indicator for the early detection of Parkinson's disease when there is a predominance of unilateral clinical symptoms.

Adult↗
PubMed1990

Volume MR angiography: methods to achieve very short echo times.

Angiographic displays of cerebral vessels can be generated with single-excitation three-dimensional magnetic resonance imaging. Differentiation of true stenosis from artifactual signal loss, due to dephasing effects from fast or nonconstant blood flow and field inhomogeneities, poses a significant clinical problem that can be largely resolved with the use of very short echo times (TEs). A three-dimensional imaging technique was developed that allows TEs of 3.1 msec without and 4.5 msec with first-order flow compensation gradients. The short TEs were achieved with short asymmetric radio-frequency pulses, gradients of minimal duration, and fractional echoes. Significantly improved images of normal tortuous vessels with fast flow were obtained. With this method, accuracy in depicting the vessel lumen and confidence in the findings were markedly increased.

Cerebral Arteries↗