In previous studies of muscle fatigue, tension was monitored from whole muscle, while action potentials were recorded from a few muscle fibers. To compare more accurately changes in these responses, an in vitro fluid electrode technique was employed to record the action potential of whole muscle simultaneously with tension during fatigue induced by nerve stimulation in the rat extensor digitorum longus (EDL), soleus, and diaphragm muscles. In each muscle, tension declined from the start of stimulation, while action potential amplitude initially increased slightly and then declined most rapidly in EDL, more slowly in diaphragm, and most slowly in soleus. Direct stimulation of the fatigued muscle produced the greatest increase in tension in EDL, next in diaphragm, and least in soleus. These results indicate that while failure of excitation-contraction coupling or of the contractile mechanism is the initial cause of fatigue in all the muscles studied, and remains the predominant cause throughout in the soleus muscle, failure of neuromuscular transmission plays an important role in fatigue after the first 15 seconds in EDL, and to a lesser extent, after the first 90 seconds in diaphragm.

Action Potentials↗

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[Dorsal occipitocervical fusion--indications and results].

STUDY DESIGN: This report will relate to our experience with the occipitocervical fusion with the y-plate, which we used in the treatment of 53 patients. METHODS: 39 of the patients had rheumatoid arthritis. Other indications demanding surgery were posttraumatic conditions, degenerative and congenital lesions, osteomyelitis, tumor and psoriasis arthritis. Before surgery, all patients suffered from pain in the neck and/or in the back of the head. On a linear scale from 0 to 10, the pain was rated as 8.0 in average (range 4 to 10). 33 patients had an instability of the atlantoaxial region and 26 patients a basilar invagination of the odontoid. A cervical myelopathy was found in 23 cases. One surgeon fused the occiput to C2 in 30 cases, to C3-C5 in 14 cases and to C7-T2 in 9 cases. In 17 patients a resection of the odontoid had to be performed before fusion to adequately decompress the spinal cord. RESULTS: 31 of the patients could be controlled with a follow-up of at average 45.9 months. 16 patients had died. At the time of follow-up, the pain was rated as 2.1 in average (range 0 to 8). The myelopathy cleared up in all cases but 3.9 patients required further operations on the cervical spine. 5 patients developed an instability at the level(s) below the fusion and an enlargement of the fusion to these levels had been performed. The fusion rate was 98.1%. The results were satisfying in 25 (80.6%) and not satisfying in 5 patients (19.4%). CONCLUSIONS: These results show the effectiveness of the occipitocervical fusion with the y-plate in a wide range of applications. It offers advantages above other techniques.

Adult↗

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Electrocardiographic changes and myocardial damage in patients with acute cerebrovascular accidents.

In 100 consecutive patients with acute cerebrovascular accident, due to cerebral thrombosis in 72, cerebral hemorrhage in 12, embolus in 6, and subarachnoid hemorrhage in 10, there were 90 who had electrocardiographic abnormalities during the first three days after admission, compared to 50% in a control group. The patients with cerebrovascular accident had a 7- to 10-fold higher incidence of ST segment depression, prolonged Q-Tc interval and atrial fibrillation, and a 2- to 4-fold higher incidence of T wave inversion, conduction defects, premature ventricular beats and left ventricular hypetrophy. Patients who died had a 2-, 3- and 5-fold higher incidence of electrocardiographic evidence of recent myocardial infarction, atrial fibrillation and conduction defects than those who survived, but these changes occurred in only 5, 21 and 14% of all patients, and other electrocardiographic changes could not be correlated with mortality. During the first three days after admission 29 patients had elevation of serum enzymes which may be derived from cardiac muscle, particularly CPK, which was increased 6-fold, compared to 2-fold increases in HBDH, GOT, and LDH. Only 5 of these patients had electrocardiographic evidence of recent myocardial infarction. Patients with elevated serum CPK had a 2-fold higher incidence of ST segment depression, T wave inversion, conduction defects and atrial fibrillation than those with normal CPK, and a mortality of 66%, compared to 30%. Of 41 patients who died, 49% had elevated serum CPK, compared to 15% of 59 patients who survived. These differences were significant (P less than 0.01). Serum CPK was more frequently helpful than the electrocardiogram in evaluating the extent of cardiac damage and in predicting mortality. Patients with acute cerebrovascular accident should have repeated evaluation of serum CPK and the ECG, and be monitored for arrhythmias.

Adult↗

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[Pain reduction by trans-articular atlanto-axial screw fixation in patients with chronic polyarthritis].

To reduce the risk of cervical myelopathy, 32 patients suffering from rheumatoid arthritis (RA) and atlanto-axial dislocation (AAD) underwent a suboccipital fusion. All patients were interviewed with a pain questionnaire after a mean postoperative follow-up of 21 months (range 2-46). The results indicate a significant postoperative pain reduction as assessed by a visual numeric analogue scale, as well as a reduction of analgesic consumption.

Adult↗

PubMedDate not supplied

Circumferential fusion of the lumbar and lumbosacral spine. Comparison of two techniques of anterior spinal fusion.

Thirty-two patients with therapy-resistant low-back pain and justified indication for fusion were divided into two groups: 16 patients were treated with anterior fusion of the lumbosacral spine, with insertion of tricortical bone grafts of the iliac crest, and 16 patients with insertion of a fibular peg. Additional dorsal fusion of the same segments was performed. Comparison of the two techniques of circumferential fusion of the lumbosacral joint reveals comparable clinical results. A marked difference in roentgenographical criteria such as disk height, retrolisthesis, and anterior osteophytes in the adjacent segment between the two techniques was noted at the time of follow-up evaluation after 89 months and motivated the authors to abandon the fibular-peg technique.

Adolescent↗