Magnetic resonance imaging and clinical correlates of intellectual impairment in myotonic dystrophy

Although intellectual impairment is common in patients with myotonic dystrophy, this aspect of the disease has received relatively little research attention. We examined 41 patients with myotonic dystrophy using objective neuropsychological procedures and magnetic resonance imaging. Ten patients (24%) had severe and generalized intellectual dysfunction, while lesser or no cognitive impairment characterized the remaining patients. Degree of intellectual impairment was not related to neuromuscular status or sex. Patients with severe intellectual disturbance had significantly earlier onset of both myotonia and weakness and were more likely to inherit the disease from their mother. Magnetic resonance imaging findings indicated that while degree of cerebral atrophy was not related to severity of intellectual impairment, skull thickness, focal white matter lesions, and anterior temporal lobe abnormalities were significantly more common in patients with severely disturbed intellect. This study reports a number of previously unreported cerebral magnetic resonance imaging findings associated with intellectual impairment in myotonic dystrophy, but the etiology of these changes awaits neuropathologic examination.     

High-resolution MR of the intraparotid facial nerve and parotid duct.

PURPOSETo describe a high-resolution MR imaging technique that depicts the complex anatomy of the region of the parotid gland, focusing on the intraparotid components of the facial nerve and parotid duct.METHODSHigh-resolution T1-weighted images of the parotid gland were acquired with a prototype three-dimensional Fourier transform gradient-echo sequence that permits a very short echo time (4.2 milliseconds) by using a modified phase-encoded time-reduced acquisition scheme. The sequences were obtained at 1.5 T with a head and neck coil. Postprocessed multiplanar, curved and volumetric images were obtained. The most clinically useful images were acquired at parameters of 40/4.2 (TR/TEeff) a flip of 30 degrees, a field of view of 18 to 20 cm, a matrix of 512 x 288 or 512 x 256, an axial plane, 60 images, no gaps, and a section thickness of 1.5 mm. Eighteen healthy subjects were examined. The position of the facial nerve within the parotid gland was determined by identifying the facial nerve in the stylomastoid foramen and then following it on sequential sections through the parotid gland. Curved reformations were used to confirm the visibility of the nerve. A similar technique was used for the parotid duct.RESULTSThe image contrast obtained was similar to that of standard spin-echo T1-weighted images. The parotid gland showed intermediate signal intensity while the fat spaces showed high signal intensity. The vessels had variable signal intensity depending on saturation. The cerebrospinal fluid, nerves, muscles, and ducts had lower signal intensity. In all 18 subjects, the facial nerve from the brain stem to the parotid gland, and the parotid duct from the mouth to the hilus of the gland were seen bilaterally. The proximal intraparotid facial nerve to the level of the retromandibular vein was seen in 72% of the subjects and the main intraparotid ducts were seen in 66% of the subjects.CONCLUSIONHigh-resolution MR imaging offers simultaneous display of most of the important structures in the region of the parotid gland, including the intraparotid duct and facial nerve.     

MEASUREMENTS OF INTERFACE PRESSURE BETWEEN BODY SITES AND THE SURFACES OF FOUR SPECIALISED AIR MATTRESSES

SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.     

Radiology and the Health Policy Agenda for the American People

Eleven radiologists appointed by the major radiological societies participated for the past 5 years in the development of the Health Policy Agenda for the American People. The Agenda is an action plan to address a wide variety of serious problems in medicine. The first phase involved establishment of 159 principles, broad value statements that were the foundation of the project. Phase 2 involved the development of policy proposals on 38 urgent issues for action in medical science; education; health resources; delivery mechanisms; evaluation, assessment, and control; and payment for services. These proposals are summarized in this report. The activities and recommendations of representatives for the field of radiology are described. The Agenda has been released, and an implementation phase has begun. It will likely be of great importance to the practice of radiology over the next decade. Important issues can be addressed by acting with the coalitions that are being formed from among the more than 150 participating organizations.     

Genetic linkage of the tricho-dento-osseous syndrome to chromosome 17q21

Tricho-dento-osseous syndrome (TDO), MIM# 190320, is transmitted as a highly penetrant autosomal dominant trait that is characterized by variable clinical expression. The principal clinical features include kinky/curly hair in infancy, enamel hypoplasia, taurodontism, as well as increased thickness and density of cranial bones. Possible genetic linkage has been reported for TDO with the ABO blood group locus, but the gene defect remains unknown. We have identified four multiplex families (n = 63, 39 affected, 24 unaffected) from North Carolina segregating TDO. We previously have excluded a major locus for TDO in the ABO region for these families. Utilizing a genome-wide search strategy, we obtained conclusive evidence for linkage of the TDO syndrome locus to markers on chromosome 17q21 (D17S791, Z max = 10.54, Theta = 0.00) with no indication of genetic heterogeneity. Multipoint analysis suggests the TDO locus is located in a 7 cM chromosomal segment flanked by D17S932 and D17S941. This finding represents the first step towards isolation and cloning of the TDO gene. Identification of this gene has important implications for understanding normal and abnormal craniofacial development of hair, teeth and bone.