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Biomedical subjects

P D Cussons

Publications and source records attributed to P D Cussons.

11 recordsLinked to original sources
PubMed2004

Reconstruction of the temporomandibular joint by the transfer of the free vascularised second metatarsal.

We present our experience of a series of patients who presented for salvage reconstruction of the temporomandibular joint (TMJ) for relief of pain. Reconstruction was achieved by transfer of the free vascularised second metatarsal. This technique has been used for a total of seven TMJ reconstructions in five patients. We describe the surgical anatomy, technique and results during the last 18 years. One joint failed but the other six surviving joints continue to provide adequate pain-free function. We advocate this technique for autogenous salvage reconstruction in joints that have been previously operated on unsuccessfully.

Adolescent↗
PubMed1996

Skin storage.

Explore the source record for details and available documents.

Cryopreservation↗
PubMed1993

A panel based assessment of early versus no nasal correction of the cleft lip nose.

There is a need to be able to assess the overall result in a significant series of cases of a method of management of the cleft lip and nose deformity in order to avoid "best case" reporting often used to introduce new techniques. The present study was performed by a panel placing standardised base view photographs in rank order. The photographs were of 10-year-old subjects of whom 15 were normal controls, 22 were from the Rikshospitalet, Oslo, all of whom had no primary nasal correction and 25 from Frenchay Hospital, Bristol, who all had radical primary nasal correction. Ranking was performed for upper nasal perimeter symmetry, nostril outline symmetry and for overall aesthetic appearance. Analysis of the results showed a significant difference between the three groups, with the corrected noses showing better symmetry. Inter and intraobserver correlations were very close. The limitations of a ranking and marking method of panel assessment are discussed, and a computerised method is presented in subsequent papers.

Child↗
PubMed1989

Comparison of the value of emergency mesenteric angiography and intraoperative colonoscopy with antegrade colonic irrigation in massive rectal haemorrhage.

The investigation of massive rectal haemorrhage has routinely included emergency mesenteric angiography to identify the site of bleeding in preparation for surgery. Nine cases over 18 months were identified from the angiography register and reviewed retrospectively. Angiography demonstrated the bleeding point in only one case, rendering colonoscopy unnecessary. However, that patient became shocked, requiring six units of blood during angiography. A second patient suffered cardiac arrest during angiography. The mean time taken was 1 1/2 h constituting a considerable delay before proceeding to surgery. On-table colonoscopy with antegrade lavage showed the bleeding site in seven out of nine cases and the mean time for operation was 3 h. One patient stopped bleeding spontaneously and there was one postoperative death from an unrelated cause. We conclude that there is no place for emergency mesenteric angiography in massive acute large bowel haemorrhage and that early surgery with antegrade colonic lavage and on-table colonoscopy is the treatment of choice.

Acute Disease↗
PubMed1980

Enhancement by agonist or antagonist muscle vibration of tremor at the elastically loaded human elbow.

1. Human subjects attempted to maintain a constant force by flexing their elbow against a spring which was attached to a force transducer at one end and the subject's wrist at the other. The tremor at 8-12 Hz which develops in this situation was enhanced in amplitude with negligible change of frequency by applying vibration at 100 Hz to the tendon either of an agonist muscle (biceps brachii) or of the antagonist (triceps brachii). The tremor was assessed by spectral analysis of the force records and measurement of the peaks in the spectra. The compliance of the spring was normally 2.8 N/mm and target forces of 40-120 N were used. 2. The percentage increase in the tremor on applying vibration was relatively independent of target force, although the absolute amounts of tremor increased markedly with increasing target force. The average increase was greater for vibration of triceps than for biceps (70% as opposed to 37%, averaged between subjects and over a range of forces). 3. When the spring was replaced by a rigid connexion there was usually no clear tremor peak either in the presence or absence of vibration. Vibration, however, tended to increase the general noisiness of the force signal. 4. Qualitatively similar effects were seen when the elbow exerted an extending force so that triceps became the agonist and biceps the antagonist. 5. The tremor peak present in the spectrum of the demodulated electromyogram during vigorous tremor increased in size when vibration made the tremor larger. 6. The effect of a rhythmic afferent input was studied by modulating the amplitude of the vibration at 8-9 Hz, to correspond to the tremor frequency, while the subject pulled against a rigid attachment. Both the e.m.g. and the tension spectra contained peaks at the modulation frequency. The raw force records showed that, with reference to the modulation, the effects of biceps and of triceps vibration were approximately 180 degrees out of phase with each other, as would occur if vibration of one were having an excitatory action, and vibration of the other an inhibitory action. Moreover, in each case the effect on force (whether excitatory or inhibitory) lagged about half a cycle on the vibration envelope, as required for such reflexes to help in the generation of tremor. 7. It is suggested that vibration increases the modulation of Ia firing elicited by a given movement tremor and this, by means of the stretch reflex arc, enhanced the tremor. The powerful action of vibration of the antagonist illustrates, it would seem, the functional effectiveness under normal conditions of a spinal inhibitory pathway, most probably the Ia disynaptic route. The findings are also discussed in relation to the increase in stretch reflex gain that occurs in association with increasing strength of voluntary contraction.

Adolescent↗
PubMed1979

Tremor in the tension developed isometrically by soleus during the tonic vibration reflex in the decerebrate cat.

1. Irregularities in the development of tension during the tonic vibration reflex of the soleus muscle of the decerebrate cat have been analysed into their frequency components. The reflex was recorded isometrically and elicited by longitudinal vibration, normally at 150 Hz. The amplitude of vibration was set so as to elicit a maximal reflex response, suggesting 1:1 driving of the majority of the Ia afferents at the frequency of vibration. 2. The resulting power spectrum regularly showed a well marked tremor peak separated by a trough from any slow irregularities. The predominant frequency of this tremor varied from 4 to 11 Hz in different preparations, with a mean of 7.4 Hz; on average, frequencies within 1.7 Hz on either side contained over half the power of the predominant frequency. Altering the frequency of vibration did not alter the distribution of tremor frequencies. 3. The root mean square value of the tension irregularities, over the range 4-14 Hz, varied from 12 to 110 mN in different preparations (median value, 23 mN); this was superimposed on mean active reflex tensions varying from 2 to 10 N. 4. The 'tremor' due to a single motor unit was estimated from spectral analysis of tetanic contractions of the whole muscle and decreased with increasing frequency of activation. Comparison of the single unit values with the tremor seen during vibration in the same preparations showed that equivalent amounts of tremor to the latter could typically have been produced by the continued synchronous contraction of about five 'average' motor units firing at the predominant tremor frequency. 5. When a tonic stretch reflex was present its tremor frequencies did not differ consistently from those of the tonic vibration reflex. On average, the tremor was smaller for the stretch reflex than for the tonic vibration reflex; the difference was usually slight and might have been related to the stretch refex tension being smaller. 6. Evidence was obtained that the tremor was not due to any insecurity of 1:1 driving of the Ia afferents by the vibration. First, the tremor did not increase when the amplitude of vibration was decreased sufficiently to ensure that the degree of 1:1 driving must have been reduced. Secondly, the introduction of a comparable 'artificial tremor' by sinusoidally oscillating the muscle at low frequency did not produce the e.m.g. response that would have been expected if the applied 'tremor' had been modulating the firing of the Ia or any other group of afferents. 7. It is concluded that the observed tremor cannot be attributed to 'oscillation in the stretch reflex arc', though without prejudice to the role of this mechanism under other conditions and especially when the recording is not isometric. However, the genesis of the tremor has not been established and much of it might result simply from the chance synchronization of motor units that are firing below their tetanic fusion frequency.

Action Potentials↗
PubMed1977

Effects of fusimotor stimulation on the response of the secondary ending of the muscle spindle to sinusoidal stretching.

1. The responsiveness of the spindle secondary ending to sinusoidal stretching has been studied using the soleus muscle of the anaesthetized cat. The sensitivity (impulses/sec firing per mm stretching) and the phase of the response were determined by computer averaging. The small linear range was studied at frequencies of 0.5-500 Hz, and also the larger non-linear range at 1 Hz.2. In the linear range, stimulation of single fusimotor fibres (which were presumed to be static axons) approximately halved the sensitivity of the ending to low frequency stretching (up to 30 Hz), but did not produce any change in the phase of the response. Thus, from the point of view of motor function, fusimotor activity provides control of gain and a biasing signal, but not control of the relative sensitivity of the secondary ending to length and velocity.3. In contrast, such stimulation slightly increased the responsiveness of the secondary ending to high-frequency stretching (100-500 Hz) and slightly advanced the phase of the response above that of the passive ending.4. The results are discussed in relation to the effect of static fusimotor stimulation on the primary ending, and to findings on secondary endings in the decerebrate cat.

Action Potentials↗