[Peroneal nerve palsy after total knee arthroplasty under continuous epidural anaesthesia]. / Peronäusläsionen nach KTEP-Implantation unter Verwendung einer postoperativ fortgeführten periduralen Analgesie.

BACKGROUND: Peroneal nerve palsy is a rare but distressing complication of total knee arthroplasty (TKA). After introducing a standardised intraoperative and postoperative epidural anaesthesia protocol under otherwise unchanged perioperative management, we noted a sudden cumulation of peroneal nerve palsies after TKA. PATIENTS AND METHODS: In this retrospective study we checked the patients' histories for well-known risk factors for nerve lesions after TKA as well as for those risk factors controversially discussed in the literature. RESULTS: We found an additive harmful impact of epidural anaesthesia leading to unrecognised pressure on the peroneal nerve, which caused, in combination with a pressure lesion of the pneumatic tourniquet, an axonal lesion in terms of a double-crush syndrome. By lowering the pneumatic tourniquet pressure and carefully positioning the operated leg, we found a clearly reduced risk of nerve lesion while preserving the advantages of epidural anaesthesia for the patient. CONCLUSION: To prevent a peroneal lesion after TKA while using continuous epidural anaesthesia, we strongly recommend limiting the pneumatic tourniquet pressure to 320 mmHg while ensuring pressure-free positioning of the operated leg.

Myopathy with abnormal mitochondria, transient low electron transport capacity in the respiratory chain, and absence of energy transduction at sites 1 and 2 in vitro.

A male adult with exercise-related myalgia and weakness from the age of 17 years, developed contractions after moderate exertion which were electrically silent. Triglyceride loading or prolonged fasting provoked excessive ketosis. His isolated muscle mitochondria had severe blockade of the respiratory chain, particularly of NADH-CoQ reductase. After 1.5 years a second biopsy was performed. The electron transport capacity of the respiratory chain was much improved, but now a lesion was observed in energy transduction of sites 1 and 2 of the respiratory chain. The unexpected abolishment of respiratory chain blockade was paralleled by only mild clinical improvement.

Spontaneous progression and regression of small carotid atheroma.

A specially designed high-resolution (10 MHz) ultrasound duplex-system was used to study prospectively the appearance of 43 extracranial non-stenotic carotid plaques (less than 30% lumen narrowing) in 31 patients over 18 months. 13 presented with ipsilateral and 9 with contralateral cerebrovascular events; 9 were asymptomatic. Most carotid atheromas remained unchanged (51%) or progressed (30%), but spontaneous regression was seen in 19% at regular 3 monthly re-examination. Regression was restricted to volume reduction of soft plaques and healing of ulcerative lesions; fibrous and hard plaques remained unchanged or progressed. Intraplaque haemorrhage was only observed in 3 instances and was always associated with later progressive encroachment. Comparison of bilateral plaques in the same individual suggested a uniform advance with duration of the atherosclerotic process. None of the patients had cerebrovascular events during follow-up.

[Development of nonstenotic extracranial carotid plaques--a prospective study of its course with the Duplex system]. / Entwicklung nichtstenosierender extrakranieller Karotis-Plaques--Eine prospektive Verlaufsuntersuchung mit dem Duplexsystem.

The natural history of a prospectively investigated group of patients with small non-stenotic extracranial carotid lesions (less than 30% lumen narrowing) was studied during 18 months. Using a specially designed high resolution (10 MHz) ultrasound Duplex system, 43 lesions were followed in 31 patients. Whereas the majority of the carotid atheromas remained unchanged (51%) or deteriorated (30%), spontaneous regression could be observed in 19%. Regression was limited to volume reduction of "soft plaques" and healing of "ulcerative" lesions, while "fibrous" and "hard plaques" remained unchanged or deteriorated. None of the patients developed cerebrovascular events during follow-up.

The clinical significance of blood-flow measurements.

The validity of different non-invasive methods of detecting extracranial arterial disease is assessed in a large series of more than 20 000 patients studied using CW-Doppler (indirect and direct techniques) and more than 2000 patients studied by a newly developed ultrasound Duplex system. While CW-Doppler analysis still represents the method of choice for the evaluation of various degrees of carotid obstructions causing more than 50 per cent lumen narrowing (overall accuracy 99 per cent), the technically far more complex and expensive Duplex systems should be used for the diagnosis of normal arterial vessels versus minor plaques, and in particular for the detection of ulcerative lesions representing possible sources of cerebral embolism. Furthermore, simultaneous flow-volume and velocity-pattern analysis across the arterial lumen provides new insight into the cerebral blood flow, thus promising acquisition, for the first time, of rapid changing parameters in the cerebral circulation.

Detection of early atherosclerotic lesions by duplex scanning of the carotid artery.

A high-resolution ultrasound B-mode imaging system combined with a 16-sequential range-gated pulsed Doppler flow measuring device was used for the evaluation of nonstenotic extracranial carotid artery disease. Various types of atherosclerotic lesions were differentiated by Duplex system examinations in 54 carotid arteries examined in vitro in a postmortem study and in 51 carotid arteries examined in vivo from patients with angiographically proven cerebrovascular disease. In addition, the multigated Doppler system allowed the analysis of flow velocity profiles throughout the carotid arteries, the distinction between intraarterial flow and recent thrombus, and in particular the estimation of local flow alterations, which are diagnostic in the presence of sonolucent and shadowed plaques behind echo-dense lesions. A number of difficulties, which at present limit the application of Duplex system examination as a non-invasive "stand alone" method for detecting carotid disease, are discussed.

The superiority of combined continuous wave Doppler examination over periorbital Doppler for the detection of extracranial carotid disease.

Non-invasive examination of 431 vessels in 333 patients with cerebrovascular disease in all stages was performed in order to compare the reliability of the periorbital Doppler test alone and together with the more difficult insonation of the carotid arteries in the neck (combined Doppler). These findings were compared with those of subsequent arteriography. Extracranial obstructive (greater than 50%) carotid disease was detected with 100% sensitivity by the combined Doppler, but with only 48% sensitivity by the periorbital indirect test. The specific ability of both methods to identify non-stenotic carotid arteries (less than 50%) was similar at about 98%. Only the combined Doppler examination reliably differentiated various degrees of obstruction, comparable to that obtained with arteriography. Non-obstructive plaques could not be detected or excluded by either Doppler test. More refined methods will be necessary for their evaluation.

Multiple exercise-related mononeuropathy with abdominal colic.

Hereditary neuropathy with liability to pressure palsies (NLPP) is a rare disease characterized by recurrent sensory-motor deficits precipitated by exposure to minor pressure. This report describes a variant of this neuropathy in 5 siblings suffering from painful palsies after strenuous work with concurrent episodes of abdominal colic resembling that of acute intermittent porphyria. Electrophysiological studies of the index case showed the typical abnormalities of motor and sensory nerve conduction, including clinically non-affected nerves. Light and electron-microscopic examination showed the characteristic lesions of the NLPP with sausage-like swelling of the myelin sheaths. In addition, non-compacted, "loose" myelin lamellae were frequently observed in association with distended Schmidt-Lantermann incisures. Non-compacted myelin was a prominent finding in this type of demyelinating neuropathy. We suggest that an unknown metabolic factor may induce both demyelination of peripheral nerve fibers and functional disturbance in autonomic nerves leading to attacks of abdominal pain.