Single photon emission computerized tomography (SPECT) in detecting neurodegeneration in Huntington's disease.

Single photon emission computerized tomography (SPECT) studies were performed on 34 manifest Huntington's disease (HD) patients at various stages of clinical pathology ranging from early chorea to late dystonia with or without signs of dementia and 12 pre-symptomatic patients with abnormal terminal CAG expansions. Thirty HD patients with obvious clinical signs and seven pre-symptomatic patients without signs or symptoms of HD displayed selective caudate hypoperfusion by direct visual inspection. Such qualitative, selective striatal hypoperfusion patterns can be indicative of early and persistent metabolic changes in striatal neuropathology. SPECT studies can be useful in documenting early pre-clinical changes in patients with abnormal terminal CAG expansions and in confirming the presence of caudate pathology in patients with clinical signs of HD.

Too many treatments for Parkinson's disease: how should they be used?

Surgical ablation for Parkinson's disease was abandoned in the 1970s after successful clinical trials of L-DOPA and L-DOPA/decarboxylase inhibitor combinations and early dopamine receptor agonists were added to prolong a viable therapeutic window beyond 5 years. The development of newer agonists with variations in receptor subtype specificity and new enzyme inhibitors with combinations of central and peripheral effects have continued to attract attention as therapeutic alternatives. Treatment options are now coming full circle with a rebirth of stereotactic neurosurgical alternatives to a wide variety of pharmacologic paradigms. The authors propose a rationale for selecting differing treatment options within historical perspective and modern treatment goals using both medical and surgical alternatives.

Rosai-Dorman disease causing cervical myelopathy.

STUDY DESIGN: A case report of a rare disease entity and review of the literature. OBJECTIVES: To illustrate the occurrence of an unusual disease affecting the spine and spinal canal. SUMMARY OF BACKGROUND DATA: Rosai-Dorman disease is considered an idiopathic benign lymphoproliferative disease that typically occurs in the earlier decades of life. The usual manifestation is painless massive cervical lymphadenopathy, although involvement of many extra nodal sites is common. This case illustrates Rosai-Dorman disease occurring in an elderly man with myelopathy and mass lesions of the cervical, thoracic, and lumbar spinal canal without typical lymphadenopathy.- METHODS: Case report illustrating clinical presentation as well as radiographic and pathologic findings, including comparisons to cases previously reported. RESULTS: Surgical decompression with incomplete resection of the lesion was performed, providing diagnosis and treatment guidance. The patient experienced significant neurologic improvement of myelopathy. CONCLUSIONS: Recognizing clinical and laboratory features of this disease may permit earlier diagnosis and limit or avoid surgical intervention in some cases.

Spin-lock magnetic resonance imaging of muscle in patients with autosomal recessive limb girdle muscular dystrophy.

Spin-lock imaging is a new magnetic resonance imaging (MRI) technique used to reflect the microstructural integrity of muscle. The purpose of this study was to characterize spin-lock contrast (SLC) of calf muscles in limb girdle muscular dystrophy (LGMD). The calf muscles of 5 patients with LGMD and 10 healthy volunteers were imaged with an off-resonance magnetic resonance (MR) spin-lock suppression pulse. Spin-lock suppression ratios were calculated for anterior tibialis, posterior tibialis, soleus, and gastrocnemius muscles. Clinical assessments of muscle strength were compared to the spin-lock suppression ratios in the LGMD group. Strong SLC was observed in healthy muscles, with mean (+/- SD) suppression ratios ranging from 51.2% (+/- 3.6%) to 56.3% (+/- 1.3%). In diseased muscle, spin-lock signal suppression was reduced by 8%-70%, demonstrating an inverse correlation between symptom duration and suppression ratios. Spin-lock contrast in the patients with LGMD, as a reflection of tissue integrity, was best preserved in posterior tibialis, anterior tibialis, soleus, and gastrocnemius muscles in descending order. Clinical assessments did a poorer job of differentiating than SLC did and were in poor agreement with spin-lock suppression ratios. Spin-lock MRI can quantify microstructural changes in LGMD and appears to provide information not obtainable from clinical evaluations. This suggests that this noninvasive technique may be useful in evaluating the extent, progression, and response to therapy of LGMD.

Magnetization transfer imaging of skeletal muscle in autosomal recessive limb girdle muscular dystrophy.

PURPOSE: The purpose of this work was to characterize magnetization transfer (MT) contrast of skeletal muscles in limb girdle muscular dystrophy (LGMD). METHOD: The calf muscles of five LGMD patients and 10 normal volunteers were imaged with an off-resonance MT suppression pulse applied to T1-weighted images. MT suppression ratios were calculated for anterior tibialis, posterior tibialis, soleus, and gastrocnemius muscles in the LGMD and control groups. The relationship between MT of individual muscles and the duration of LGMD symptoms was determined. RESULTS: Strong MT contrast was observed in normal calf muscles, with mean (+/-SD) suppression ratios ranging from 37.9% (+/-3.0) to 41.1% (+/-2.1). In diseased muscle, MT signal suppression ranged from 11 to 38%, demonstrating an inverse relationship between symptom duration and suppression ratios. MT contrast in the LGMD patients, as a reflection of muscle tissue integrity, was preserved in posterior or anterior tibialis, soleus, and gastrocnemius muscles, respectively. Suppression ratios were dramatically reduced in muscles with gross fatty infiltration but also were reduced in muscle tissues without visual evidence of fatty infiltration. CONCLUSION: MT imaging provides a quantitative measure of pathologic changes occurring within the skeletal muscles of patients with LGMD relative to normal and may be useful in evaluating disease extent, progression, and response to new therapies as they become available.

Acoustic echoplanar scanner noise and pure tone hearing thresholds: the effects of sequence repetition times and acoustic noise rates.

PURPOSE: Our goal was to determine the effects of acoustic echoplanar scanner noise on pure tone hearing thresholds in normal volunteers and to determine the influence of echoplanar sequence repetition time on threshold effects. METHOD: With use of a calibrated audiometer, pure tones ranging from 125 to 8,000 Hz were delivered monaurally to 10 normal-hearing volunteers in a quiet MR scanner suite and in the presence of acoustic scanner noise produced by three separate single shot blipped echoplanar pulse sequences varying only in repetition time (TR = 1,000, 2,000, or 3,000 ms), with all other parameters including the number of slices held constant. The magnitude of noise-induced threshold changes and the slopes of the threshold curves produced by each of the three echoplanar pulse sequences were then analyzed using multiple comparisons and a least significant difference method. The shapes of the threshold curves produced in each background state were best fit using a quadratic effect for frequency in a mixed effects linear model and compared using F test statistics. RESULTS: All of the volunteers demonstrated entirely normal hearing thresholds throughout the full range of tonal frequencies tested (< 25 dB) when no acoustic scanner noise was present in the scanner suite. Pure tone hearing thresholds significantly increased (p < 0.01) in the presence of acoustic scanner noise, with the magnitude of change inversely proportional to the repetition time and therefore the rate of periodic noise production by the echoplanar sequence used. The shape of the threshold curve in the presence of noise produced by the 1,000 ms TR sequence was not equivalent across the frequency spectrum tested but had a quadratic distribution with peak effects at 750-2,000 Hz. As the repetition time was increased and the periodic noise rate decreased, the magnitude of the noise-induced threshold changes significantly lessened (p < 0.01) and the quadratic distributions of the threshold curves changed significantly (p < 0.01), tending toward a more planar configuration. CONCLUSION: Background acoustic echoplanar scanner noise can significantly increase pure tone thresholds in the optimal frequency hearing range (125-8,000 Hz). However, the threshold effects are not equivalent across the frequency spectrum, and the magnitude of threshold changes is dependent on the rate at which periodic acoustic scanner noises are produced for a given sequence repetition time.

Near-resonance saturation pulse imaging of the extraocular muscles in thyroid-related ophthalmopathy.

PURPOSE: We examined the utility of near-resonance saturation pulse imaging (magnetization transfer [MT] and spin lock) in characterizing microstructural changes occurring in the extraocular muscles of patients with thyroid-related ophthalmopathy (TRO). METHODS: Eight healthy volunteers and 10 patients with TRO were imaged using an off-resonance saturation pulse in conjunction with conventional spin-echo T1-weighted imaging at frequency offsets of 500, 1000, 1500, and 2000 Hz from water resonance. The relative contributions of MT and spin-lock excitation to image contrast at each frequency offset were estimated using a computer simulation model. Suppression ratios were calculated for the control and TRO groups from measurements obtained on two successive coronal sections in the widest portion of the inferior and medial rectus muscles bilaterally. A repeated measures analysis of variance and a parametric correlation analysis were performed to evaluate maximum cross-sectional area, MR-generated signal, and suppression ratios for the extraocular muscles examined. RESULTS: Our computer model suggested that saturation of extraocular muscles was due to pure MT effects with our off-resonance pulse at 2000 and 1500 Hz, to a combination of MT and spin lock at 1000 Hz frequency offset, and, primarily, to spin-lock excitation at 500 Hz frequency offset. Suppression ratios for the extraocular muscles of the TRO patients were significantly lower than that observed for the control subjects at 1500, 1000, and 500 Hz frequency offset. This differential saturation effect was maximal at 500 Hz frequency offset, with mean suppression ratios for the inferior and medial rectus muscles of 27% for the healthy subjects and 20% for the TRO group. CONCLUSION: Both MT and spin-lock contrast of the extraocular muscles in patients with TRO differ significantly from that observed in control subjects. Near-resonance saturation pulse imaging may enhance our understanding of the microstructural changes occurring in the extraocular muscles of these patients.

Understanding the brain stem.

This article highlights features of brain anatomy that are important to know in interpreting magnetic resonance images. This article concentrates on the names of some brain stem structures, the three-dimensional appearance of six important tracts, and the location of cranial nerve nuclei.

Cortical activation response to acoustic echo planar scanner noise.

PURPOSE: Our goal was to determine the distribution of auditory and language cortex activation in response to acoustic echo planar scanner noise with functional MRI (fMRI). METHOD: Acoustic scanner noise and spoken text, reproduced on high output cassette tape, were separately delivered at equivalent intensities to six normal hearing adult volunteers through earphones during fMRI data acquisition. In nine other subjects, taped scanner noise was delivered in five successive iterations of the task to assess the consistency of cortical activation to the noise stimulus. Gyri of the auditory and language system were divided into 10 different subregions for analysis of cortical activation. The number of activated pixels and proportion of volunteers activating each cortical subregion were determined using a cross-correlation analysis. RESULTS: Cortical activation to taped acoustic scanner noise was present within the transverse temporal gyrus (primary auditory cortex) in all subjects, but activation was highly variable between subjects in auditory association and language relevant cortex. Auditory association cortex activation was seen in the planum polari, planum temporali, and middle temporal gyrus/superior temporal sulcus regions in one-half to two-thirds of the volunteers. There was no significant difference in the distribution of cortical activation within individual subjects across five successive iterations of the scanner noise task. Listening to spoken text consistently activated primary and association auditory cortex bilaterally as well as language relevant cortex in some cases. The mean number of activated pixels was significantly greater for text listening than acoustic scanner noise in auditory association and language relevant cortical subregions (p < 0.01), although the distribution of activity was similar between the two tasks. CONCLUSION: This preliminary investigation suggests that the complex sounds produced by the echo planar pulse sequence can activate relatively large regions of auditory and language cortex bilaterally, with the extent of activation outside the primary auditory cortex being variable between subjects. However, the distribution of activation within individual subjects was relatively constant across several iterations of the scanner noise stimulus.

Recent advances in MR spectroscopy expand its applications in neurologic disease.

MRS extends the diagnostic power of MRI by displaying the biochemical composition of a selected tissue or region. When MR imaging shows a lesion, the evaluation of the chemical composition by MRS can help determine whether biopsy, observation or medical treatment is indicated. It can save some patients from biopsy prior to radiation or chemotherapy. In the future, both the image information and the spatial distribution of chemical constituents throughout the brain will be displayed with techniques such as chemical shift imaging (CSI). MRS improves the accuracy of MRI diagnosis and prognosis. MRS is performed at many sites in the country and is reimbursed by many insurers. MRS has been approved by the AMA for a CPT-4 code for reimbursement.

MR imaging of lumbar spondylolysis: the importance of ancillary observations.

OBJECTIVE: The purpose of this study was to determine the frequency of characteristic ancillary MR findings in patients with lumbar spondylolysis. MATERIALS AND METHODS: The radiology reports and clinical records of 64 patients (16 female, 48 male; 12-77 years old) with 66 levels of lumbar spondylolysis who had undergone MR imaging were retrospectively reviewed. Spondylolysis was established by conventional radiography in all 64 patients and by CT in 18 patients. The proportion of patients with spondylolysis in whom sagittal MR images showed ancillary findings of an increased sagittal diameter of the spinal canal, reactive marrow changes in the pedicle, or abnormal wedging of the posterior aspect of the vertebral body was retrospectively determined. This proportion was then compared with the proportion of patients in whom spondylolysis was correctly diagnosed by the initial interpreters of the MR images, who used only direct visualization of defects of the pars interarticularis to make the diagnosis. RESULTS: Twenty (30%) of 66 levels of lumbar spondylolysis were misdiagnosed when the MR images were initially interpreted using direct visualization of defects of the pars interarticularis. An increased sagittal diameter of the spinal canal was the most common ancillary observation, occurring at 60 of 66 levels of lumbar spondylolysis. This finding was present in all patients with grade II, III, or IV spondylolisthesis, in 95% of patients with grade I spondylolisthesis; and in 77% of patients with no anterolisthesis. Thirty-two (48%) of 66 lumbar levels showed wedging of the posterior aspect of the vertebral body, which correlated significantly with the grade of spondylolisthesis. Reactive marrow changes in the pedicle distinct from normal adjacent levels were seen on MR images in 24(36%) of 66 levels of lumbar spondylolysis. On MR images, 97% of all levels of lumbar spondylolysis yielded one or more ancillary observations, including all 20 of the cases originally misdiagnosed. CONCLUSION: The combined use of ancillary observations and direct visualization of pars interarticularis defects makes MR imaging effective in revealing lumbar spondylolysis.

Anatomic relationship of the oculomotor nuclear complex and medial longitudinal fasciculus in the midbrain.

PURPOSE: To compare the MR characteristics of the oculomotor nucleus with its appearance on anatomic images. METHODS: Specimens of cadaveric brains were imaged in a 3.0-T MR imager equipped with a 3.0-cm solenoid coil. The specimens were sectioned, stained, and examined histologically. On anatomic sections, the oculomotor nuclei, medial longitudinal fasciculus, red nuclei, and oculomotor nerve were identified. The MR images were then compared with the anatomic sections. RESULTS: The oculomotor nuclei, medial longitudinal fasciculus, red nuclei, and oculomotor nerve could be identified on MR images by their size, shape, signal intensity, and location. CONCLUSION: MR images show the anatomic relationship of the oculomotor nerve complex, medial longitudinal fasciculus, and related structures in the brain stem.