Magnetic resonance imaging in the evaluation of cerebrospinal fluid flow abnormalities

Phase contrast magnetic resonance imaging techniques can be used to evaluate the to-and-fro motion of cerebrospinal fluid (CSF) throughout the ventricles and subarachnoid space of the brain and spine. This CSF motion is due to transmitted cardiac pulsations from systolic expansion of the cerebral hemispheres. To cover the entire cardiac cycle, retrospective cardiac gating (rather than electrocardiographic triggering) must be used. Using this technique, it is possible to quantify CSF motion over a cardiac cycle and to distinguish normal aqueductal CSF "stroke volumes" from those seen in atrophy and shunt-responsive communicating hydrocephalus. Arachnoid cysts and other loculated CSF collections can be diagnosed using a "rebound sign" in which the motion of the CSF within the cyst is 90 degrees phase advanced over the CSF flowing around it.

Flow dynamics of cerebrospinal fluid: assessment with phase-contrast velocity MR imaging performed with retrospective cardiac gating

To visualize the flow of cerebrospinal fluid (CSF) throughout the ventricles and subarachnoid space, measure mean and maximum CSF velocities, and quantitate CSF flow through the aqueduct of Sylvius, magnetic resonance (MR) imaging was performed with a sagittal technique that is flow-sensitive in the craniocaudal direction (along the readout axis) and a high-resolution axial technique sensitive to through-plane flow in three healthy subjects and 19 patients with known or suspected disorders of the CSF circulation. In both techniques, retrospective cardiac gating was used to cover the complete cardiac cycle. The sagittal technique was superior in overall assessment of CSF flow dynamics, including the motion of adjacent brain parenchyma. The high-resolution axial technique provided an accurate measurement of the rate of CSF flow through the aqueduct; only this technique provided sufficient accuracy to enable distinction between normal and hyperdynamic CSF flow. It is concluded that assessment of CSF flow dynamics is a useful adjunct to routine MR imaging in communicating and obstructive hydrocephalus.

Quantitative P-31 MR spectroscopy of the liver in alcoholic cirrhosis

To determine the cause of reduced urea synthesis in cirrhosis, absolute concentrations of phosphorus metabolites in the human liver have been measured in vivo with magnetic resonance (MR) spectroscopy. One-dimensional chemical shift imaging was used to obtain phosphorus-31 spectra from five healthy volunteers and five patients with alcoholic cirrhosis. A reference standard included in all studies enabled the calculation of absolute concentrations. In contrast to hepatic metabolite ratios, absolute concentrations reveal that in the cirrhotic patients, concentrations of adenosine triphosphate (ATP) were significantly reduced and concentrations of phosphomonoesters slightly reduced. Intracellular pH was unchanged. Histologic evidence suggests that the amount of ATP per cell was unchanged and could not account for the reduced urea production. Instead, urea synthesis depends on the functional liver cell mass, which was reduced by 31% in alcoholic cirrhosis. Quantitative in vivo P-31 MR spectroscopy of liver has potential clinical applications and can supplement the more generally used P-31 metabolite ratios.

Clinical safety and efficacy of gadoteridol: a study in 411 patients with suspected intracranial and spinal disease

In this phase III study, 411 adult patients with suspected intracranial or spinal disease underwent magnetic resonance (MR) imaging before and after intravenous injection of 0.1 mmol/kg gadoteridol (gadolinium 1,4,7-tris [carboxymethyl]-10-[2'-hydroxypropyl]-1,4,7,10-tetraazacyclododecane+ ++). MR images were evaluated by a single unblinded reader at each of 27 sites; the diagnosis was confirmed with one of nine imaging or surgical procedures within 8 weeks before or after MR imaging. After injection, no clinically significant changes were noted in laboratory values, physical examination, or vital signs. Adverse clinical events possibly or probably associated with injection of gadoteridol were seen in 18 of 411 patients (4.4%); the most common were dysgeusia and mild nausea, and all abated without residual effects. MR images enhanced with gadoteridol in patients with confirmed disease provided more diagnostic information than unenhanced images in 128 of 175 brain examinations (73.1%) and 93 of 137 spinal examinations (67.9%). A change in diagnosis because of additional information from contrast-enhanced images was considered likely in 63 of 214 cranial and 54 of 161 spinal studies.

Multicenter study of gadodiamide injection as a contrast agent in MR imaging of the brain and spine

To evaluate the safety and efficacy of gadodiamide injection, a nonionic gadolinium chelate complex, in magnetic resonance (MR) imaging of the head and spine, a phase II-III trial was conducted in 439 patients with known or suspected lesions in the central nervous system. All patients received gadodiamide injection in a dosage of 0.1 mmol/kg and were monitored; MR images were evaluated for contrast material enhancement. No serious adverse events or clinically important trends in vital signs, laboratory values, or neurologic status were observed. Gadodiamide injection enhanced or facilitated the visualization of lesions in 266 or 353 patients (75.4%) in whom lesions were shown on unenhanced images, enhanced images, or both; in these 266 patients, the diagnosis was changed in 76 patients (28.6%) and facilitated in 190 patients (71.4%). It is concluded that gadodiamide injection is safe and effective for MR imaging of the head and spine in patients with suspected abnormalities of the central nervous system.

The effects of long-term non-fatiguing resistance exercise in subjects with post-polio syndrome

Measures of torque were used to evaluate changes in muscle strength and endurance in 17 patients with post-polio syndrome who did prescribed resistance exercise for up to 2 years. Exercise compliance averaged 75%, with 16 subjects increasing the weight lifted in training. Maximum torque was significantly increased in the exercised muscle compared to the control muscle; no difference was seen in muscle endurance. Individuals with post-polio syndrome can increase muscle strength by doing non-fatiguing resistance exercise, but they should undergo quantitative testing of muscle strength a minimum of every 3 months to guard against overwork weakness.

Effect of arm rotation on MR imaging of the rotator cuff

The effect of humeral rotation on the appearance of the rotator cuff tendon in oblique coronal magnetic resonance images was evaluated in 70 such images. Internal rotation produced overlap of the supraspinatus and infraspinatus tendons with soft-tissue interposition or apparent discontinuity of the tendon in 22 cases, including 14 of 15 shoulders positioned in the first 30 degrees between extreme internal and external rotation. Imaging in internal rotation makes assessment of the tendon difficult and should be avoided.

Cervical spine hyperextension injuries: MR findings

Cervical hyperextension injuries are common and often show minimal radiographic abnormalities, even with severe or unstable lesions. Fourteen patients, nine with acceleration hyperextension "whiplash" injuries and five injured by direct frontal head trauma, underwent magnetic resonance (MR) imaging within 4 months of injury. Five of seven patients with anterior spinal column injuries showed characteristic separation of the disk from the vertebral end plate, lesions still evident as late as 9 months after injury. The demonstration of this type of lesion and its delayed resolution may have prognostic and surgical implications. These lesions, anterior longitudinal ligament injuries, anterior annular tears, and occult anterior vertebral end-plate fractures usually occurred at multiple levels except when preexistent degenerative disk narrowing reduced spine mobility. Seven patients had acute cervical disk herniations causing cord impingement. Radiographically occult injuries are well demonstrated with MR imaging, and findings correspond to previously described surgical and anatomical pathologic conditions.

Inclusion body myositis with cricopharyngeus muscle involvement and severe dysphagia

A patient with inclusion body myositis (IBM) is presented. Unusual aspects of this case include a myopathy of 36 years duration, severe dysphagia due to cricopharyngeus muscle dysfunction, improvement with cricopharyngeus myotomy, and a diagnostic cricopharyngeus muscle biopsy.

A soluble factor induced by an extract from Pinus parviflora Sieb et Zucc can inhibit the replication of human immunodeficiency virus in vitro

We showed that an extract (PC6) from cones of Pinus parviflora Sieb et Zucc induced the human T-cell line CEM to produce a pepsin-sensitive soluble factor(s) that could inhibit the replication of the type 1 human immunodeficiency virus (HIV-1) in CEM T cells, in U-937 histocytes, in THP-1 monocytes, and in mitogen-activated human tonsillar mononuclear cells. Indirect immunofluorescence staining and polymerase chain reaction analysis of the PC6-induced CEM cells revealed the absence of known lymphokines/cytokines except granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), transforming growth factor beta 1 (TGF-beta 1), and tumor necrosis factor alpha (TNF-alpha). However, functional studies with recombinant IL-3, TNF-alpha, and TGF-beta 1 showed that these three factors did not inhibit HIV-1 replication in CEM cells. Neutralization of the PC6-induced HIV-1-inhibiting factor(s) with commercially available neutralizing antibodies to GM-CSF and TNF-alpha also did not abrogate the anti-HIV-1 impact. Thus, the anti-HIV-1 factor induced by PC6 may be novel. Molecular sieve separation showed that the anti-HIV-1 factor(s) is smaller than 30 kDa. Affinity chromatography using a DEAE-cellulose column enriched the factor that inhibited HIV-1.

Marked cerebrospinal fluid void: indicator of successful shunt in patients with suspected normal-pressure hydrocephalus

The authors blindly reviewed the charts of 20 patients with normal-pressure hydrocephalus (a disease of unknown cause characterized radiologically as chronic communicating hydrocephalus and clinically by gait apraxia, dementia, and incontinence) who had undergone creation of a ventriculoperitoneal shunt. The initial clinical response to surgery was graded excellent, good, fair, or poor; 5-year follow-up was available in 55% of cases. The magnetic resonance (MR) images obtained in these patients were also blindly reviewed for the magnitude of cerebrospinal fluid (CSF) flow void (graded on the basis of extent rather than degree of signal loss) in the cerebral aqueduct. A significant (P less than .003) correlation existed between good or excellent response to surgery and an increased CSF flow void. The presence of associated deep white matter infarction on MR images did not correlate with a poor response to surgery. On the basis of these findings, it is suggested that patients who fulfill the clinical criteria of NPH and have an increased CSF flow void undergo creation of a shunt.

Association of deep white matter infarction with chronic communicating hydrocephalus: implications regarding the possible origin of normal-pressure hydrocephalus

The coexistence of cerebrovascular disease leading to deep white matter infarction and normal-pressure hydrocephalus has been noted previously in clinical studies, as both diseases can present with the triad of gait disturbance, dementia, and incontinence. The purpose of this MR study was to determine if the two diseases demonstrated a statistical association. Evidence of patchy periventricular hyperintensity representing presumed deep white matter infarction was sought in 20 patients shunted for normal-pressure hydrocephalus and in 35 additional consecutive patients with clinical symptoms and MR findings consistent with normal-pressure hydrocephalus. Deep white matter infarction was also sought in 62 consecutive age-matched control subjects. There was a statistically significant (p less than .001) higher association (58%) of marked infarction in the 55 patients with normal-pressure hydrocephalus than in the age-matched controls (24%). MR findings of communicating hydrocephalus (ventriculomegaly and increased aqueductal CSF flow void) were sought in 78 consecutive patients with presumed deep white matter infarction, and the degree of severity of the two diseases was also found to be statistically significant (p less than .05). In view of this association, the possibility that the two diseases are related was considered. A potential mechanism is discussed whereby deep white matter infarction leading to decreased periventricular tensile strength could result in communicating hydrocephalus. It is plausible that normal-pressure hydrocephalus may result from a number of different insults to the brain.

Congenital monomelic hypertrophy with progressive myopathy

We describe a patient with congenital monomelic hypertrophy who later developed progressive footdrop due to a degenerative myopathy. The clinical, electrophysiologic, and pathologic features of the case are described and compared with those of a previously reported case.

Cytokine regulation of the human immunodeficiency virus (HIV)

The remarkable ability of HIV to insinuate itself into the working of the immune system is the key of its success as an infectious agent. Given that the cytokine network regulates the immune responses, it is not surprising that cytokines can modulate HIV infection. GM-CSF, IL6 and TNF-alpha enhance HIV, but TGF-beta and HIF inhibits the virus. However, the anti-HIV activity of TGF-beta is restricted to myeloid cells, while HIF inhibits HIV in myeloid cells and in T-lymphocytes. HIF is produced by CEM cells after induction by an extract from pine cones. It is not an interferon and is likely a novel cytokine. It is pepsin-sensitive but trypsin-resistant and has an apparent molecular weight of 7-12 KDa. Apart from having anti-HIV activity, crude preparations of HIF also inhibit HTLV-1 virus but not HSV virus replication.

The "notch" sign: meniscal contour deformities as indicators of tear in MR imaging of the knee

Conventional magnetic resonance (MR) criteria for meniscal tearing emphasize intrameniscal signal and its communication with the articular surface. In this retrospective study, the value of a focal contour deformity of the meniscal articular surface, termed a "notch," as an additional MR sign of meniscal tearing was assessed. One hundred fifty-four menisci were evaluated. Twenty-three of 24 notches correlated with the site of tear at arthroscopy. Seven notches improved the reading confidence from possible to definite tear; in eight notches, the diagnosis of tear would otherwise not have been considered. Five tears occurred without intrameniscal signal, four following recent trauma. The notch sign improved the sensitivity from 79.8 to 87.8%. Notches are useful additional signs of meniscal tearing, increasing the confidence of a reading when occurring near grade 1 or 2 meniscal signal, and are the only MR sign present in some tears.

Critical review of gangliosides and thyrotropin-releasing hormone in peripheral neuromuscular diseases

The lack of effective therapy for many of the chronic neuromuscular diseases such as amyotrophic lateral sclerosis, hereditary motor sensory neuropathy (Charcot-Marie-Tooth disease), spinocerebellar degenerations and idiopathic polyneuropathy has led to a search for substances that may stimulate peripheral nerve regeneration. Two such agents that have been proposed are gangliosides (mixed purified bovine brain gangliosides, Cronassial) and thyrotropin releasing factor (TRH). Studies on both of these agents were initially reported with enthusiasm to be successful, but later double-blind controlled studies have failed to confirm these findings. This review provides critical analysis of the designs of studies of potentially effective agents in chronic neuromuscular diseases, and emphasizes the power of the placebo response, and the importance of designing placebos which are indistinguishable from the trial medication other than in the active effect.

Progressive myopathy in hyperkalemic periodic paralysis

A progressive degenerative myopathy has been well described in hypokalemic periodic paralysis but is not as widely recognized in hyperkalemic periodic paralysis. We studied four families with the latter disease in which some members developed a progressive myopathy. Episodes of paralysis were prolonged, lasting for months in some cases, and in one case paralysis was sufficiently severe to require ventilatory support. The progressive myopathy tended to develop at a time when attacks of paralysis were decreasing in frequency. Muscle biopsy specimens showed variability in fiber size, internal nuclei, and fibers with vacuoles. Electron microscopy showed myofibrillary degeneration and tubular aggregates. An abnormal biopsy specimen was more common in older patients. Our experience suggests that a progressive myopathy is as common in hyperkalemic periodic paralysis as it is in the hypokalemic disorder.

Focal neuropathy preceding chronic inflammatory demyelinating polyradiculoneuropathy by several years

We report three patients who exhibited an unusual clinical course of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) in which mononeuropathic limb weakness developed 2, 11 and 23 years, respectively, before the development of generalized polyradiculoneuropathy. The eventual diagnosis remained uncertain until other causes of neuropathy were excluded, and the clinical disorder progressed to involve the other limbs. Focal or regional variants of CIDP suggest that the pathologic, and perhaps the immunologic, abnormalities can be localized and selective for prolonged periods of time. Although this clinical variant seems to account for a small number of CIDP cases, its recognition may aid in making an early diagnosis.

Gradient-echo MR imaging of the lumbar spine: comparison with spin-echo technique

Gradient-echo (GRE) magnetic resonance (MR) imaging has been advocated as the imaging modality of choice for evaluating radiculopathy in the cervical spine. Axial GRE images of the lumbar spine in 50 patients were compared with similar images obtained using spin-echo (SE) technique on a 1.5 T MR system. The SE images were superior to GRE images in the evaluation of the neural foramina, epidural fat, and disk herniation. The GRE images obtained were inadequate for lumbar spine imaging due to an unacceptable level of chemical shift artifacts. The GRE technique does provide the advantages of rapid acquisition of T2* images and decreased motion artifact. Axial GRE images may play an increasingly important role in lumbar spine imaging with continued changes in software and improvements in technology.

Acute hematomas: effects of deoxygenation, hematocrit, and fibrin-clot formation and retraction on T2 shortening

Acute hematomas can appear hypointense on T2-weighted magnetic resonance (MR) images at field strengths as low as 0.35 T. Using Raman spectroscopy to measure blood oxygenation and taking T2 measurements at 2.1 and 9.4 T, the authors examined the relaxation mechanisms acting during deoxygenation, increases in hematocrit, and fibrin-clot formation and retraction. Individual contributions to overall T2 from deoxyhemoglobin and the interactions of water with protein hydration layers in hemoglobin, plasma proteins, and fibrin were measured. Overall T2 values estimated by summing individual relaxation rates were in reasonable agreement with the T2 values of clotted blood. Results suggest that deoxygenation may be most important in T2 shortening, followed by increased hematocrit. T2 shortening from fibrin polymerization was minimal at the field strengths used. Effects of deoxygenation and increasing hematocrit are more sensitive to field strength than fibrin T2 shortening. Effects of fibrin may be more significant at middle and low field strengths.

Chronic segmental spinal muscular atrophy of upper extremities in identical twins

We present the 1st report of chronic segmental spinal muscular atrophy confined to the upper extremities in identical male twins. This occurrence in identical twins, together with reports of siblings and parent-child pairs of a disorder phenotypically similar to the more common sporadic form in the literature, suggests a genetic etiology in some cases.