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Biomedical subjects

R M Braun

Publications and source records attributed to R M Braun.

At least 19 recordsLinked to original sources
PubMed1998

Vacuum ultraviolet single photon versus femtosecond multiphoton ionization of sputtered germanium clusters.

Neutral atoms and clusters desorbed from a solid germanium surface by ion bombardment are detected by laser postionization and time-of-flight mass spectrometry. Two different photoionization schemes are compared which are generally believed to be candidates for the 'soft' ionization of polyatomic species without significant photon induced fragmentation. First, a single photon ionization process is employed using an F2 laser as an intense VUV source with a photon energy in excess of all relevant ionization potentials. It is shown that the available laser pulse energy is sufficient to saturate the ionization of Ge atoms and all detected Ge(n) clusters. The resulting mass spectra are compared to those obtained with a non-resonant multiphoton ionization process using a high intensity laser delivering pulses of 250 femtoseconds duration at a wavelength of 267 nm. Also in this case, the ionization process can apparently be driven into saturation. The mass spectra measured under these conditions are found to be almost identical to those obtained using single photon ionization. We take this as an indication that the results obtained with both postionization techniques closely reflect the true cluster sputtering yields and, in particular, are not dominated by photon induced fragmentation.

Absorptiometry, Photon↗
PubMed1998

Performance characteristics of a chemical imaging time-of-flight mass spectrometer.

A chemical imaging time-of-flight secondary ion mass spectrometer is described. It consists of a liquid metal ion gun, medium energy resolution reflectron mass analyzer, liquid nitrogen cooled sample stage, preparation chamber and dual stage entry port. Unique features include compatibility with laser postionization experiments, large field of view, cryogenic sample handling capability and high incident ion beam current. Instrument performance is illustrated by the characterization of scanning electron microscopy grids, silver and functionalized polystyrene beads and the postionization of an organic overlayer on a gold substrate.

Diagnostic Imaging↗
PubMed1998

Postionization of molecules desorbed from surfaces by keV Ion bombardment with femtosecond laser pulses.

We report the use of femtosecond laser photoionization of sputtered neutral molecules to enhance the sensitivity of detection and to improve the prospects for molecule-specific imaging experiments. Results are presented for patterned metal oxides, polycyclic aromatic hydrocarbons and several amino acids. In addition to increased signal levels, we find that is photoionization generally yields simpler mass spectra than the corresponding SIMS spectra, although considerable fragmentation is observed in both cases.

Amino Acids↗
PubMed1997

Dynamic MR imaging of carpal tunnel syndrome.

OBJECTIVE: To evaluate the diagnostic value of the MR imaging syndrome before and after performance of provocative exercises in patients with dynamic carpal tunnel syndrome. DESIGN: Fat-suppressed proton-density and T2-weighted spin-echo images of the wrist were obtained prior to and after provocative, standardized exercises. Images were interpreted in masked fashion with regard to six MR criteria of carpal tunnel syndrome: (a) bowing of the transverse ligament, (b) and (c) deformation of the median nerve at the pisiform and hamate levels respectively, (d) signal abnormality of the median nerve, (e) presence of fluid in the wrist joints and/or carpal tunnel, and (f) presence of synovial swelling. PATIENTS: Twenty-one wrists in 20 patients with subjective complaints of carpal tunnel syndrome and equivocal or negative clinical findings and negative electrodiagnostic examinations were included (age range 21-61 years, mean 37 years, 2 men and 18 women). The diagnosis of dynamic carpal tunnel syndrome was made and confirmed by surgery in 18 of the 21 symptomatic wrists. The control group consisted of 15 asymptomatic wrists in volunteers (age range 22-60 years, mean 35 years, 8 men and 7 women). RESULTS AND CONCLUSIONS: Sensitivities and specificities of the six MR criteria were 90.5-100%, and 6.7-86.7%, respectively, both before and after exercise. Likelihood ratios proved statistically significant differences between the symptomatic and asymptomatic wrists (P < 0.0001-0.0002) for the prevalence of all MR criteria with the exception of fluid within the carpal joints and/or carpal tunnel. Changes of the MR appearance after exercise had a low sensitivity (4.8-71.4%) but high specificity (86.7-100%) for dynamic carpal tunnel syndrome. In conclusion, MR imaging contributes to the diagnosis of carpal tunnel syndrome when clinical signs are confusing and electrodiagnostic studies are negative. Dynamic examinations improve specificity of MR imaging for such diagnosis.

Adult↗
PubMed1997

Bilateral thenar hammer syndrome as a result of cumulative trauma: a case report.

This report describes an unusual case of bilateral radial artery thrombosis associated with multiple weblike stenoses and pseudoaneurysms secondary to cumulative trauma in a manual laborer who used both hands for impacting at both the thenar and hypothenar aspects of the hand. In this case, thenar hammer syndrome was associated with acute ischemia of the long finger. The condition was treated surgically with arterial resection and reestablishment of blood flow to the hand. Noted improvement occurred with restoration of arterial competence.

Aneurysm, False↗
PubMed1995

The retrograde radial fascial forearm flap: surgical rationale, technique, and clinical application.

The retrograde radial fascial forearm flap may be used to provide appropriate tissue coverage for nerve, tendon, or soft tissue defects in the forearm and hand. The procedure is differentiated from the standard radial forearm flap in that the radial artery remains intact when the retrograde radial fascial flap is designed. The rationale, technique, and clinical application of the flap are presented in order to allow surgeons to maintain the radial arterial trunk in continuity while obtaining the advantage of appropriate soft tissue cover in this critical area.

Adult↗
PubMed1994

Electrical studies as a prognostic factor in the surgical treatment of carpal tunnel syndrome.

We attempted to determine if a prognostic value could be associated with preoperative electrodiagnostic testing in patients with carpal tunnel syndrome. Three groups of patients were included in the study of 151 workers whose symptoms were thought to be causally related to their jobs. A clinical diagnosis was made without electrical testing in 26 of the 151 patients. Normal electrical test values were present in 50 of the 125 patients tested, and abnormal values were noted in 75 patients. Pinch, power, and static grasp function were recorded monthly. Similar recovery patterns after operation were seen between the groups and within each group. Return to work time correlated well with measured functional recovery to preoperative levels, but some workers returned to their jobs before they had regained full function. Electrodiagnostic test results did not provide significant data for prediction of functional recovery or re-employment after carpal tunnel release.

Adult↗
PubMed1994

Dorsal pin placement and external fixation for correction of dorsal tilt in fractures of the distal radius.

Insertion of a dorsal fixation pin was performed in 10 patients treated for distal radius fractures associated with dorsal angulation of the distal fragment. These fractures did not improve position with direct traction. Reduction was achieved with the use of a dorsal pin, used as a lever, to correct dorsal tilt of the fracture and to reestablish anterior angulation of 10 degrees in the distal joint surface of the radius. The dorsal pin was then fixed to an external fixator bar. All of these fractures healed in good position with appropriate alignment and without complications.

Adult↗
PubMed1992

The distal joint of the radius and ulna. Diagnostic studies and treatment rationale.

Three areas of functional anatomy are present in the distal ulna. Each of these has a specific function in load bearing of the wrist, rotation of the forearm, and maintenance of the relationship between the radius and ulna. The distal portion of the ulna serves as a suspensory post for ligaments that stabilize the ulnar border of the wrist. The midportion of the distal ulna contains the load-bearing triangular fibrocartilage complex. The proximal portion of the distal ulna articulates with the radius at the sigmoid notch and participates in forearm rotation. Each of these areas is assessed in problems related to ligament instability, load bearing, and range of motion. Mechanical problems that affect the distal joint of the radius and ulna include the affects of trauma, degenerative change, and inflammatory disease. Each of these requires evaluation in the treatment of joint derangement. Diagnostic studies that relate to problems in the distal radioulnar joint area include standard roentgenographs, arthrograms, magnetic resonance (MR) scanning, and arthroscopy. Each of these studies has particular advantages and disadvantages in providing data for analysis of joint malfunction. A medical history, physical examination, and use of proper diagnostic studies will assist in an appropriate diagnosis of problems in the distal joint of the radius and ulna.

Adult↗
PubMed1991

Spontaneous bilateral median nerve compressions in the distal arm.

A case of bilateral median nerve compressions in the distal arm is described. The patient was seen initially with the spontaneous onset of paresis of the anterior interosseous nerve innervated muscles, as well as more proximal median nerve innervated muscles. There was no shoulder-girdle weakness or sensory abnormality. No systemic symptoms were identified. Surgical exploration in each extremity revealed enlarged communicating veins directly compressing the median nerve in the distal arms. Clinical improvement began 6 months after operation and was complete by 18 months.

Adult↗
PubMed1989

Provocative testing in the diagnosis of dynamic carpal tunnel syndrome.

This study measures the effects of provocative testing on a series of patients with latent symptoms of carpal tunnel syndrome. Forty patients were studied for change in hand volume and loss of sensibility after stress. Thirty-four patients demonstrated significant measurable increase in hand volume after a 7-minute stress test. In 17 of 34 patients impaired sensibility associated with swelling developed and they were considered to have dynamic carpal tunnel syndrome. Surgical treatment was effective in correcting symptoms and sensory defects in these 17 individuals despite postoperative hand swelling that continued after the operation when the hand was subjected to stress.

Adult↗
PubMed1989

Carpal tunnel syndrome: morphologic changes after release of the transverse carpal ligament.

We describe the morphologic changes that follow division of the transverse carpal ligament in patients with carpal tunnel syndrome. Fifteen hands in 12 patients with carpal tunnel syndrome were studied with magnetic resonance imaging before operation and for 6 weeks after operation. Eight hands were studied at 8 months after operation. Carpal arch width, anterior displacement of the carpal canal contents, and carpal canal volume were measured by use of multiplanar reformation and three-dimensional reconstruction of magnetic resonance images. There was a 24.2 +/- 11.6% increase in carpal canal volume 6 weeks after carpal tunnel release (p less than 0.001). This difference persisted at 8-month follow-up. There was an anterior displacement of carpal canal contents 3.5 +/- 1.9 mm from its original position 6 weeks after operation (p less than 0.001). This palmar displacement persisted at the 8-month follow-up. There was no statistically significant increase in carpal arch width 8 months after carpal tunnel release. We believe that division of the transverse carpal ligament restores median nerve function by increasing the volume of the carpal canal. This volumetric increase results from an anterior displacement of the newly formed transverse carpal ligament and not from a widening of the bony carpal arch.

Carpal Bones↗
PubMed1986

Distal interphalangeal joint involvement in rheumatoid arthritis.

Sixty-two patients with seropositive rheumatoid arthritis (RA) were evaluated radiographically for distal interphalangeal (DIP) joint involvement and were compared with 50 age- and sex-matched control subjects. The frequency of DIP erosions was 37% in the patients versus 14% in the controls; these erosions were mild and were not related to disease duration. Erosions elsewhere in the hand and wrist were of all degrees of severity and were related in part to disease duration. Osteophytes occurred frequently in both the RA group (71%) and the control group (60%). However, joint space narrowing occurred more frequently in RA patients (77%) than in the controls (46%) (P less than 0.009). The findings from this study suggest that in RA patients, DIP erosions occur frequently, do not occur in isolation, and are not simply a marker for severe global erosive disease in the hand and wrist. The high frequency of osteophytosis and joint space narrowing in both groups probably represents the overlap of osteoarthritis and RA that occurs in many patients.

Arthritis, Rheumatoid↗
PubMed1985

Dynamic compression for small bone arthrodesis.

A technique providing dynamic compression for arthrodesis of the small joints in the hand uses a longitudinal wire for alignment and two 0.045 Kirschner wires and methyl methacrylate cement for continuous dynamic compression. Thirty-one joints, 12 metacarpophalangeal and 19 interphalangeal, were arthrodesed by this method. There were no angular malunions or nonunions. The technique is recommended as an alternative to current fixation methods in the hand for small joint arthrodesis.

Arthrodesis↗
PubMed1985

Total joint arthroplasty at the carpometacarpal joint of the thumb.

A series of 50 cases of total joint arthroplasty at the carpometacarpal joint of the thumb demonstrate surgical procedure and cement technique. Most patients showed a full range of motion within four weeks of suture removal and continue to demonstrate good long-term results. Less motion is anticipated in patients with contractures or systemic disease. Five patients showed clinical or radiographic evidence of loosening. Revision procedures document the retrieval potential of a failed implant. The author's ten-year experience with this system indicates that the concept is viable. Future modifications are discussed.

Carpal Bones↗