Incidence, recovery, and management of serratus anterior muscle palsy after axillary node dissection.
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The purposes of this study were to determine the occurrence of serratus anterior muscle weakness after axillary node dissection, to monitor the recovery of serratus anterior muscle strength, and to compare shoulder range of motion in palsied and nonpalsied groups. Thirty-six patients were studied who had 40 axillary node dissections for breast carcinoma or malignant melanoma. Range of motion and manual muscle tests were done preoperatively and at specific postoperative intervals by two observers. To regain range of motion, all subjects were treated daily while hospitalized and as needed when outpatients. Twelve of the 40 dissections (30%) resulted in serratus anterior muscle palsy after surgery. Strength was normal in all the palsied shoulders by the sixth month after surgery. Both the palsied and nonpalsied groups had comparable range of motion at each assessment. The mechanism of long thoracic nerve injury and the clinical significance of serratus anterior muscle palsy are discussed as well as the rationale for early detection and proper physical therapy management. This study suggests that serratus anterior muscle palsy is a frequent but reversible event after axillary node dissection. (+info)
Variations in the time course of the synchronization of intercostal motoneurones in the cat.
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1. Synchronization of intercostal motoneurones was studied by the construction of cross-correlation histograms which related the firing times of paired groups of efferent inspiratory or expiratory discharges recorded from filaments of the external or internal nerves of anaesthetized or decerebrate cats.2. The principal feature of the histograms was always a central peak but the time course of the central peak showed considerable variation. Three forms of synchronization were defined on the basis of the time course of the central peak: (i) short-term synchronization (Sears & Stagg, 1976), where the peak was narrow, extending over about +/-3 ms but sometimes with weak shoulders to about +/-5 ms; (ii) broad-peak synchronization where the peak was wider than this (often +/-20 ms or more) but where there were no strong periodicities; (iii) high-frequency oscillation (h.f.o) synchronization, which was named from the related phenomena in medullary and phrenic recordings (Cohen, 1979), where there were periodic peaks on either side of the central peak with a frequency in the range 60-120 Hz. Combinations of these forms of synchronization were seen in some histograms.3. When different animals were compared, broad peak synchronization was seen in association with light anaesthesia and with polysynaptic excitation of the motoneurones from muscle spindle afferents.4. In individual animals, additional anaesthesia depressed both broad peak and h.f.o. synchronization.5. Raising P(A, CO2), which increased the respiratory drive to the motoneurones, favoured short-term or h.f.o. synchronization at the expense of broad-peak synchronization.6. In three decerebrate animals only short-term or h.f.o. synchronization was seen.7. Spinal cord lesions above or below the segments of interest promoted broad-peak synchronization, even with high P(A, CO2) or deep anaesthesia.8. We conclude: (i) that short-term synchronization, due mainly to the branching of presynaptic axons, is generated mainly by those axons which transmit the respiratory drive, that drive providing most of the excitation of the motoneurones in moderately deep anaesthesia; (ii) that h.f.o. synchronization arises from the periodic synchronization of the discharges in these same presynaptic axons; (iii) that broad-peak synchronization is generated by the activity of other presynaptic neurones whose discharges are also synchronized, but aperiodically, these neurones most likely including spinal cord interneurones which are active in light anaesthesia or when released by spinal cord lesions.9. These conclusions are supported by comparisons between intracellular recordings from inspiratory motoneurones in animals showing different forms of motoneurone synchronization, the comparison including the measurements of ;average common excitation' (a.c.e.) potentials (Kirkwood & Sears, 1978). (+info)
The spatial distribution of synchronization of intercostal motoneurones in the cat.
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1. The three different types of synchronization of intercostal motoneurones which were described in the preceding paper (Kirkwood, Sears, Tuck & Westgaard, 1982) were studied for motoneurones of the same segment or for different segmental separations (up to five segments) and for motoneurones on opposite sides of the same segment.2. The strength of synchronization declined with segmental separation for all three categories, although the rate of decline was more variable for broad-peak synchronization than for the two other types. Short-term synchronization was undetectable for separations greater than three or four segments but clear peaks were still visible in the cross correlation histograms for high-frequency oscillation (h.f.o.) or broad-peak synchronization at a segmental separation of five. Synchronization between motoneurones on opposite sides of the cord was generally weak although less so for broad-peak or h.f.o. components.3. The decline in strength of short-term synchronization with segmental separation could not be explained by temporal dispersion of impulses in presynaptic axons.4. A time shift was observed in the position of the cross-correlation histogram peak which was dependent on segmental separation and equivalent to a mean descending conduction velocity of 28 m/s in the assumed common input. This figure is similar to the mean conduction velocity of bulbospinal respiratory neurones derived from published values.5. We conclude that the short-term synchronization in these preparations is generated by the bulbospinal respiratory neurones and that the majority of their axons do not branch to make strong synaptic connexions to motoneurones over more than three to four segments.6. Interpretations of the different distributions of the other types of synchronization are discussed. (+info)
Recurrent inhibition of intercostal motoneurones in the cat.
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1. The external and internal intercostal nerves of a single intercostal space were stimulated in anaesthetized paralysed cats with dorsal roots cut in the corresponding spinal cord segment. 2. Extracellular recording in the ventral horn revealed single units which fired short high frequency bursts of spikes at short latency to stimulation of either or both of the two nerves at stimulus strengths appropriate to the activation of alpha motor axons. These units were deduced to be Renshaw cells. 3. Small (0.1-0.2 mV) hyperpolarizing potentials of duration up to 50 msec were recorded intracellularly in both inspiratory and expiratory motoneurones of the same segment. Latencies and thresholds were appropriate for disynaptic i.p.s.p.s evoked by collaterals of alpha motor axons. 4. The changes in probability of firing following the stimuli were examined for inspiratory alpha motoneurones by constructing post-stimulus histograms of efferent discharges recorded from filaments of the external intercostal nerve of the segment stimulated and from other segments. 5. A period of reduced probability of firing of up to 24 msec duration, corresponding in all respects to disynaptic inhibition from alpha motor axon collaterals, was seen in the segment stimulated and up to three segments distant, though declining in intensity with distance. Either nerve could evoke such inhibition although that evoked from the internal intercostal nerve was stronger, as were the intensities of the Renshaw cell discharges. 6. We conclude that recurrent inhibition, via Renshaw cells which have axons up to 30 mm in length, is present for intercostal motoneurones. Arguments are adduced to show that although the effects from stimulating any one segmental nerve may be relatively weak, the over-all effect resulting from the widely spread projections of the Renshaw cells concerned is an inhibition comparable intensity with that seen in many hind limb motor nuclei. (+info)
Electrodiagnostic confirmation of long thoracic nerve palsy.
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Long thoracic nerve latencies were measured in 25 normal subjects. The nerve was stimulated at Erb's point. Monopolar electrodes were used to record the motor evoked response from the serratus anterior muscle. The mean long thoracic nerve latency was 3.9 +/- 0.6 ms. Four athletes with unilateral, isolated long thoracic nerve palsies were compared with the control group and with the uninvolved extremities. Long thoracic nerve latency examinations may help confirm the presence of long thoracic nerve palsy and test proximal nerve conduction. (+info)
Winging of the scapula: an unusual complication of chest tube placement.
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Chest tube insertion is generally considered a safe procedure. We describe a patient who developed winging of the scapula following chest tube insertion. This complication has not been documented before. (+info)
The dorsal scapular nerve and long thoracic nerve of 10 cadavers (20 sides) and 36 patients with dorsal scapular nerve compression were studied anatomically. The origin of the dorsal scapular nerve of a section frequently shared a common trunk with the long thoracic nerve, and went through the scalenus medius anterointernally and posterolaterally with the presence of some tendinous tissues. Leaving the long thoracic nerve, it might give branches to the shoulder and the subaxillary region and finally have the branches join the long thoracic nerve again. The compression of the section near the origin caused discomfort and sourness of the neck, shoulder and back region. Clinically, the severance of the scalenus anterior and medius ameliorated or relieved the compression of the dorsal scapular nerve. Complete decompression required cutting of the scalenus medius and its tendinous tissue superficial to the dorsal scapular nerve. Among 24 sides of 22 patients undergoing surgery, the symptoms of 20 sides of 19 patients were completely or partially relieved. (+info)
Tracheal anaesthesia for transthoracic endoscopic sympathectomy: an alternative to endobronchial anaesthesia.
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When using endobronchial anaesthesia for the management of transthoracic endoscopic sympathectomy (TES), excessive insufflation of carbon dioxide into the pleural space may cause haemodynamic instability, hypoxaemia and tension pneumothorax. We prospectively studied an alternative technique using a tracheal tube, i.v. fentanyl, propofol, atracurium and nitrous oxide in 82 consecutive healthy patients (31 male, 51 female; mean age 26.48 (range 14-50) yr, weight 61.26 (33-100)kg.) They were suffering from severe palmar hyperhidrosis and they underwent bilateral TES (mean duration of operation 34.57 (15-90) min). After being placed in a 30-40 degree head-up position, three patients required ephedrine to treat arterial hypotension. A capnograph was used to confirm correct placement of the Verres needle in the pleural space. In two groups of 13 patients undergoing ventilation with an FlO2 of either 0.3 or 0.4, during partial collapse of the operative lung, PaO2 and the PaO2:FlO2 ratio decreased significantly (P < 0.001). TES was unsuccessful in three patients because of pleural adhesions. After operation five patients required chest drains; two for haemothorax and three for pneumothorax. Seventy-seven patients without complications were discharged from hospital within 24 h. (+info)