Changes in heart rate and R-wave amplitude with posture.

BACKGROUND: Effect of gravity on heart rate and blood pressure are well documented but the effect of posture on R-wave amplitude has not been studied. AIM: To investigate the effect of posture on the heart rate (HR) and R-wave amplitude (RWA). METHODS: The electrocardiograph (ECG) was recorded in 20 young subjects on two occasions. A 5 minute recording of resting ECG was taken with the subject adopting the following postural cycle: lying, sitting, standing, sitting and lying positions. RESULTS: The standing HR was significantly higher than that in sitting and lying positions, but the RWA was significantly lower in standing compared to the sitting and lying postures. The HR significantly increased at the initial phase of postural changes, irrespective of the position. For example, the HR increased from lying to sitting (66.6+/-2.3 to 85.0+/-10.9 beat x min(-1)) but also increased when changed from sitting to lying (70.6+/-10.6 to 85.2+/-8.7 beat x min(-1)). CONCLUSION: Body posture has an effect on HR and RWA. The changes are probably related to orthostatic haemodynamic stress as well as changes in cardiac electrical axis. Whether the cause of the initial increase in the HR during postural change was attributed to skeletal muscle reflex or venous return requires further investigation.

Sensory impairment after resection of the mandible: a case report of 10 cases.

PURPOSE: In patients who have undergone mandibular resection for benign tumors involving the inferior alveolar nerve, some recovery of the neurosensory impairment in the lower lip and chin region may occur. This study investigated the extent of the residual neurosensory impairment to the lower lip and chin on the resected side. PATIENTS AND METHODS: Ten patients who underwent resection of ameloblastoma of the mandible involving the inferior alveolar nerve but not crossing the midline were evaluated by questionnaire and neurosensory testing for the extent of residual neurosensory impairment. RESULTS: Neurosensory tests showed that there was moderate recovery, especially in the sensation of light touch and temperature. Two-point discrimination and brush directional discrimination showed the poorest recovery. CONCLUSION: All patients suffered some degree of neurosensory deficit, but there was definitely some recovery, especially in patients younger than 16 years. Most of the patients had adapted well and had minimal physical and social problems as a result of the neurosensory deficit.

Odontogenic keratocyst: a clinical experience in Singapore.

The odontogenic keratocyst has been well documented and extensively studied. It is of particular interest because of its high recurrence rate and aggressive nature. The material for this study consisted of 70 cases of odontogenic keratocysts in predominantly ethnic Chinese patients who were treated from 1981 to 1996. The cases were retrospectively studied to compare characteristics of the lesion in this population with those in previous reports. Most of the patients in this series were 21 to 30 years of age. Association with an impacted mandibular third molar was found in more than 50% of the cases. The recurrence rate was 20% for 35 patients with a follow-up period of at least 5 years. The follow-up period for the whole series ranged from 1 to 16 years. Treatment was surgical enucleation with peripheral ostectomy. There were no significant differences in characteristics with respect to presentation and prognosis between this series and those described in previous publications.