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Biomedical subjects

F M Howard

Publications and source records attributed to F M Howard.

At least 55 records · Page 3Linked to original sources
PubMed1989

Stiff-man syndrome updated.

Stiff-man syndrome, a rare disorder characterized by intermittent spasms and stiffness of the axial muscles, is associated with an electromyographic pattern of continuous motor unit activity in affected muscles. Since the initial description in 1956, the stiff-man syndrome has been reported to occur in various clinical and neurologic settings. In this study, we reviewed the current state of knowledge about this syndrome, defined diagnostic criteria, provided a long-term follow-up of the disorder, and assessed rehabilitative attempts in affected patients. Use of rigorous criteria that identify patients who have the stiff-man syndrome is important because the initial clinical manifestations are similar to those of other neuromuscular diseases. Analysis of 13 patients with stiff-man syndrome examined at the Mayo Clinic during the past 30 years revealed that treatment with diazepam decreased the muscle spasms. Because some muscle spasms usually persist, rehabilitation is an important adjunct that may further improve function when it is centered on the treatment of low-back pain and hyperlordosis, mobility problems, gait abnormalities, and muscular stiffness.

Adult↗
PubMed1988

Striational autoantibodies: quantitative detection by enzyme immunoassay in myasthenia gravis, thymoma, and recipients of D-penicillamine or allogeneic bone marrow.

Striational autoantibodies (StrAb) are a useful serologic marker of thymoma in patients with myasthenia gravis (MG). We compared a standard immunofluorescence method with a new enzyme immunoassay (EIA) for detection of StrAb. Retrospective testing of 264 stored sera by the two methods yielded well-correlated results (58 sera were positive by both assays; r = 0.8). For 104 patients with spontaneously acquired MG or thymoma, results were 100% concordant, of which 53% were positive. For 34 recipients of D-penicillamine, StrAb were found in 15% by EIA and in 6% by immunofluorescence. StrAb were detected in two of four bone marrow recipients by EIA and in one by immunofluorescence. Prospective testing of 434 fresh sera (of which 49 were positive by the two methods) yielded discordant results in only 4. Serial EIA quantitation of StrAb in two patients with MG and thymoma proved useful in monitoring immunosuppressant therapy and in a third patient predicted recurrence of the tumor. A high prevalence of StrAb was detected by both assays in elderly patients with spontaneous MG, but StrAb were more readily quantifiable by EIA. The EIA method proved to be highly sensitive and specific for detecting StrAb in patients with thymoma with and without MG, in patients treated with D-penicillamine, and in those with graft-versus-host disease after bone marrow transplantation.

Adolescent↗
PubMed1987

Serum antibodies and monoclonal antibodies secreted by thymic B-cell clones from patients with myasthenia gravis define striational antigens.

The biochemical identities of several antigens to which striational antibodies bind were determined by using serum antibodies and monoclonal antibodies from two patients with myasthenia gravis. The monoclonal antibodies were secreted by EBV-transformed B-lymphocyte clones obtained from thymus and thymoma. Serum and monoclonal antibodies reacted with discrete components of the skeletal muscle sarcomere, giving rise to several different patterns of immunofluorescence staining. Immunoblot analyses and enzyme-linked immunosorbent assays revealed three different antibody specificities: myosin, alpha-actinin, and/or actin. Individual monoclonal StrAb reacted with both muscle and nonmuscle isotypes of actin or myosin. It is noteworthy that contractile proteins (1) are associated with acetylcholine receptors (AChR) in plasma membranes, and (2) are biochemically altered in transformed cells. It is therefore conceivable that the release of neoantigenic AChR-associated contractile proteins from thymic epithelial cells undergoing neoplastic transformation may provide the immunogenic stimulus for production of StrAb. More precise definition of StrAb specificities in individual patients with MG and/or thymoma might provide a basis for diagnostic and/or prognostic classification of these diseases. Furthermore, the monoclonal antibodies will be useful in experimentally testing the potential pathogenicity of StrAb.

Actinin↗
PubMed1987

Clinical correlations of antibodies that bind, block, or modulate human acetylcholine receptors in myasthenia gravis.

Acetylcholine receptor (AChR) binding and AChR modulating antibodies were found with approximately the same frequency (86%) in 349 patients with myasthenia gravis (MG). However, the total yield of positive serological results was significantly improved (90%) by assaying AChR modulating antibodies when AChR binding antibodies were not detected, because in 27 patients (8%) only one of the two tests was positive. The immunoprecipitation test for AChR blocking antibodies yielded fewer positive results (52%), but there was a significant correlation between the degree of AChR blockade and generalization of muscle weakness. In no patient was this the only positive test, because the test for AChR modulating antibodies in this study detected both AChR blocking and modulating antibodies. Human muscle AChR was used as antigen in all tests. False positive results were rare and were attributed to unexplained antibodies to 125I-alpha-Bgt (AChR binding antibody assay) and recent general anesthesia using muscle relaxants (AChR blocking and AChR modulating antibody assays). Unexplained positive results, documented previously in 5% of patients with the Lambert-Eaton myasthenic syndrome and amyotrophic lateral sclerosis (ALS), were found in this study in two of 22 patients with ALS, but in none of 427 patients with miscellaneous neurological diseases. Patients with severe generalized MG and/or thymoma tended to have higher titers of AChR binding antibodies and greater AChR modulating antibody activity. However, some patients with severe muscle weakness had low titers of antibodies, and some patients in remission or with only ocular manifestations had high titers. These seemingly paradoxical results reflect heterogeneity in the specificities, affinities, and isotypes of anti-AChR antibodies. To effect pathogenicity, antibodies must have access in vivo to extracellular antigenic sites on the AChR. One would anticipate that antibodies with greatest pathophysiological potential would be of an IgG with greatest pathophysiological potential would be of an IgG subclass that activates complement, or of a specificity that competes for acetylcholine's binding site on the receptor or readily cross-links two AChR molecules to trigger receptor modulation (e.g., by binding to sites on the duplicated alpha-subunit). In patients with suspected MG who lack serological evidence of anti-AChR antibodies, motor endplate biopsy is required for microelectrophysiological, immunochemical, and ultrastructural studies to establish with certainty whether or not the condition is acquired MG.

Autoantibodies↗
PubMed1987

Fractures of the basal joint of the thumb.

The two important fractures of the trapeziometacarpal joint are Bennett's fracture and Rolando's fracture. Bennett's fracture is a fracture-dislocation of the joint. The preferred treatment is closed reduction and percutaneous pinning of the fracture with additional fixation through the trapeziometacarpal joint verified by anteroposterior (AP) and lateral roentgenograms. If the fracture is not reducible, and open reduction through the thenar approach with Herbert screw fixation is recommended. Rolando's fracture is a comminuted T- or Y-shaped fracture through the base of the first metacarpal. The preferred treatment is an external fixator accompanied by the tension band wiring technique.

Fractures, Bone↗
PubMed1986

Controversies in nerve entrapment syndromes in the forearm and wrist.

The five tunnels of the forearm and wrist, where nerve entrapment most frequently occurs, have been analyzed for diagnosis, treatment, anatomic variations, and prognosis. The value of a positive EMG report is to reinforce a clinical impression. If negative, it does not exclude the entrapment syndrome. When the diagnosis is accurate, the timing of surgery precise, and the surgical technique meticulous, the results from nerve entrapment surgery can be the most rewarding of all upper extremity surgery.

Carpal Tunnel Syndrome↗
PubMed1986

Compression neuropathies in the anterior forearm.

In nerve entrapment syndromes in the upper extremity, the surgeon must first become a diagnostician. When the symptoms of entrapment are bilateral, diabetes mellitus and cervical arthritis are found in a significant statistical number over the general population. These diseases can result in incomplete relief of symptoms, even after decompression of the entrapment. In Upton's double crush theory, proximal nerve impingement can cause increasing symptoms distally and this can account for some failures following carpal tunnel surgery. Bilateral carpal tunnel patients are often predisposed by anatomically small carpal tunnel canals, cervical arthritis, or diabetes mellitus. Usually, with a precise diagnosis and a careful treatment plan, excellent results can be achieved with removal of the anatomic constriction or mechanical block.

Electrodiagnosis↗
PubMed1986

The unreduced carpal dislocation. A method of treatment.

Unreduced lunate, perilunate, and transscaphoid perilunate dislocations present a difficult and challenging surgical problem. The authors feel that all efforts should be made to obtain a reduction of the old dislocation. They support a combined dorsal and palmar approach, open reduction, and internal fixation of scaphoid with a Herbert screw to obtain midcarpal stability. A carpal tunnel decompression should be performed if symptoms suggest median nerve entrapment. When the dislocation is unable to be reduced, the authors favor limited wrist arthrodesis or a proximal row carpectomy in the absence of significant arthritis.

Adolescent↗
PubMed1985

The incomplete anterior interosseous nerve syndrome.

The anterior interosseous nerve syndrome involves paralysis of the flexor pollicis longus, flexor digitorum profundus of the index and long fingers, and the pronator quadratus. We have encountered 33 cases of an incomplete syndrome in which only the flexor pollicis longus or the flexor digitorum profundus of the index finger is either paretic or paralyzed. This entity must be distinguished from flexor tendon rupture, flexor tendon adherence or adhesion, and stenosing tenosynovitis. The nerve is usually compressed by fibrous bands that most commonly originate from the deep head of the pronator teres and to the brachialis fascia. Less common causes of compression are: fibrous bands from the superficial head of the pronator teres; bands from the superficialis arcade; the nerve running deep to both heads of the pronator; and compression by a double lacertus fibrosus. Patients presenting with paresis should be observed. Most will improve spontaneously without surgery. We recommend exploration and neurolysis of the anterior interosseous nerve in patients who present with complete paralysis of either muscle-tendon unit and who have shown no improvement as determined by physical examination or repeat electromyography after 12 weeks of observation. Recovery after neurolysis is often rapid and complete.

Adolescent↗
PubMed1985

Silastic condylar arthroplasty.

Interpositional Silastic condylar arthroplasty of the first carpometacarpal joint was used in 40 patients with disabling arthritis. Limiting bone resection at the base of the thumb improves prosthetic stability. Pain was lessened and function improved in most cases. Technical modifications and their rationale are discussed.

Aged↗
PubMed1985

Diarrhoea: after rehydration, what next?

Successful management of diarrhoea depends firstly on restoring fluid and electrolyte balance. Following this, the child needs to be fed, to prevent malnutrition and morbidity. Conventionally, this is achieved by regrading onto the previous feed. In our series of 42 infants with mild gastroenteritis, six out of 12 infants had persistent diarrhoea after one week on normal infant formula. Twenty-five out of 27 infants who were given a low-lactose formula (HN25) had normal stools within 4 days. (chi2 = 18.487; P less than 0.001). Only two out of 27 infants had a recurrence of loose stools at 1 week and these became normal after regrading back on to HN25. Recovery time was shortened, while nutritional status was maintained. Short-term substitution of a low-lactose formula after rehydration speeds recovery from gastroenteritis.

Combined Modality Therapy↗
PubMed1984

Giant cell tumor of the capitate.

A case of giant cell tumor of the capitate is presented. Its recurrence and the problem of reconstruction after resection are discussed. Recommended treatment of this tumor if it occurs within the carpals is resection of the carpus with intercarpal arthrodesis if the distal row is involved or proximal row carpectomy if the scaphoid or lunate is involved.

Adolescent↗
PubMed1984

Plasmapheresis in the treatment of ventilator-dependent myasthenia gravis patients. Report of four cases.

During a 42-month period, we used plasmapheresis to treat four cases of myasthenia gravis with refractory respiratory failure. All four patients were ventilator dependent for prolonged periods and were not responding to management with cholinesterase inhibitors and corticosteroids. All four patients rapidly responded to the plasmapheresis; respiratory muscle strength returned sufficiently to allow discontinuation of assisted mechanical ventilation and removal of the artificial airway. In our experience, plasmapheresis is indicated in the treatment of the myasthenia gravis patient with respiratory failure which is refractory to conventional drug therapy.

Adult↗
PubMed1984

Postoperative respiratory care after transsternal thymectomy in myasthenia gravis. A 3-year experience in 53 patients.

During a three-year period, 53 patients with myasthenia gravis underwent transsternal thymectomy by a partial sternum-splitting technique at our institution. This procedure was carried out (1) because an x-ray film or a computed tomography scan had suggested the presence of a thymoma or (2) to manage symptoms of myasthenia gravis. In 41 patients the endotracheal tube was removed in the post-anesthesia recovery room. The remaining 12 patients were extubated in the Respiratory Care Unit--in five, after prolonged mechanical ventilation. From our experience, the only factor useful for predicting the probable need for prolonged postoperative mechanical ventilation is the degree of bulbar involvement. Patients in Osserman classification groups 3 and 4 have an extremely high incidence of postoperative respiratory failure. Consideration should be given to the use of preoperative plasmapheresis in myasthenia gravis patients who have significant bulbar symptoms.

Adolescent↗
PubMed1983

Syringomesencephalia. Report of a case.

A woman had progressive neurologic deterioration attributed to multiple sclerosis. Ophthalmologic findings were consistent with a unilateral lesion of the medial longitudinal fasciculus. Autopsy disclosed a mesencephalic syrinx and cerebellar atrophy secondary to alcoholism. Syringomesencephalia is distinctly uncommon; this is the third known case to our knowledge.

Adult↗
PubMed1983

Myasthenia gravis in children: long-term follow-up.

We report observations made on 149 patients with juvenile myasthenia gravis studied from onset of disease for as long as 40 years. Median follow-up was 17 years; minimum was 4 years. Eight other patients with congenital myasthenia gravis were studied separately. Of the juvenile myasthenic patients, 85 (57%) underwent thymectomy because of diseases severity. In juvenile myasthenia gravis, a spontaneous remission rate of 22.4 per 1,000 person-years was observed, regardless of disease duration. A remission rate of 260 per 1,000 person-years was seen during the first year after thymectomy, with a rate of 95 per 1,000 person-years during the next 2 years. Early surgery, presence of bulbar symptoms, absence of ocular signs or generalized symptoms, onset of symptoms between ages 12 and 16, and presence of other immune disease were associated with increased postoperative remission rates. Epilepsy (4 patients) and neoplasia (7 patients) were the most frequent associated nonimmune disorders; rheumatoid arthritis (5 patients), juvenile-onset diabetes mellitus (3 patients), asthma (3 patients), and thyroid disease (3 patients) were the most frequent associated immune diseases.

Adolescent↗