RESUMO
Knowledge about biological rhythms of diseases may not only help in understanding the pathophysiology of diseases but can also help health service policy makers and emergency department directors to allocate resources efficiently. Aneurysmal subarachnoid haemorrhage (SAH) has high rates of morbidity and mortality. The incidence of SAH has been attributed to patient-related factors such as characteristics of aneurysms, smoking, and hypertension. There are studies showing that the incidence of aneurysmal SAH appears to behave in periodic fashions over long time periods. However, there are inconsistencies in the literature regarding the impact of chronobiological factors such as circadian, seasonal, and lunar cycle factors on the occurrence of SAH. In this study, we focused on the analysis of a temporal pattern of SAH (infradian rhythms) with a novel approach using circular statistical methods. We aimed to see whether there is a circular pattern for the occurrence of SAH at all and if so, whether it can be related to known temporal patterns based on available literature. Our study did not support the notion that aneurysmal subarachnoid haemorrhages occur on any specific day in a cycle with specific lengths up to 365 days including specific weekdays, full moon, equinoxes, and solstices. Hence, we found no relationship between SAH incidence and timing. Study in larger populations using similar circular statistical methods is suggested.
RESUMO
OBJECTIVES: To review previous reports as well as our institutional experience to address the issues regarding patient management and also to assess the predisposing factors that might influence outcome and survival. METHODS: We undertook a 20-year (1989-2009) retrospective study of a series of eight patients diagnosed with intramedullary spinal cord metastases (ISCMs) in our institute. We further reviewed 293 cases of ISCMs reported in the English literature since 1960. Characteristics regarding the site of the primary cancer, location of ISCM, the presence of other metastases, presenting neurological symptoms/signs, duration of symptoms, and the time interval from diagnosis of the primary tumor to ISCM were pooled. We analyzed the different treatment approaches, the functional outcome, and the factors influencing survival. RESULTS: Lung and breast cancers appear to be the most frequent source of ISCM with cervical, thoracic, and lumbar spine being equally affected. Motor weakness predominates as the commonest symptom at presentation, followed by pain and sensory disturbance. At diagnosis, most patients with ISCM have a known primary cancer often associated with cerebral and other systemic metastases. Overall survival of ISCM is poor (median: 4 months from the time of diagnosis). Survival in surgical patients is 6 months, compared with 5 months in those conservatively managed. Clinical improvement was observed in more than one-half of those treated surgically, whereas neurological status was maintained in most patients treated conservatively. CONCLUSION: ISCM is an unusual site for metastasis. Regardless of the treatment, its prognosis is generally poor as its presence often signifies end-stage cancer. However, with early diagnosis and appropriate treatment, selected patients may benefit from improved neurological outcome and quality of life.