Alteration of brain functional network at rest and in response to YMCA physical stress test in concussed athletes: RsFMRI study.

There is still controversy in the literature whether a single episode of mild traumatic brain injury (mTBI) results in short- and/or long-term functional and structural deficits in the concussed brain. With the inability of traditional brain imaging techniques to properly assess the severity of brain damage induced by a concussive blow, there is hope that more advanced applications such as resting state functional magnetic resonance imaging (rsFMRI) will be more specific in accurately diagnosing mTBI. In this rsFMRI study, we examined 17 subjects 10±2 days post-sports-related mTBI and 17 age-matched normal volunteers (NVs) to investigate the possibility that the integrity of the resting state brain network is disrupted following a single concussive blow. We hypothesized that advanced brain imaging techniques may reveal subtle alterations of functional brain connections in asymptomatic mTBI subjects. There are several findings of interest. All mTBI subjects were asymptomatic based upon clinical evaluation and neuropsychological (NP) assessments prior to the MRI session. The mTBI subjects revealed a disrupted functional network both at rest and in response to the YMCA physical stress test. Specifically, interhemispheric connectivity was significantly reduced in the primary visual cortex, hippocampal and dorsolateral prefrontal cortex networks (p<0.05). The YMCA physical stress induced nonspecific and similar changes in brain network connectivity patterns in both the mTBI and NV groups. These major findings are discussed in relation to underlying mechanisms, clinical assessment of mTBI, and current debate regarding functional brain connectivity in a clinical population. Overall, our major findings clearly indicate that functional brain alterations in the acute phase of injury are overlooked when conventional clinical and neuropsychological examinations are used.

[Long-term results (6 to 17 years) of 372 mitral valve replacements using the Björk-Shiley prosthesis]. / Résultats lointains (six à dix-sept ans) sur 372 patients du remplacement valvulaire mitral par prothèse de Björk-Shiley.

From November 1970 to December 1981, an isolated mitral valve replacement was performed in 372 patients (166 males - 206 females), ranging in age from 2 months to 76 years (mean age 49 years). Eighty-nine patients (24%) had previously undergone one or two cardiac operations. Only one of the 24 hospital deaths (6.4%) was related to the prosthesis (early thrombosis). Three hundred and fourty-eight patients were discharged from the hospital, 35 were lost to follow-up, and 313 were observed with a mean follow-up of 8 years 8 months (ranging from 5 years 2 months to 16 years 3 months). Ninety-two patients (29.4%) died from 2 months to 16 years post-operatively. Thirteen late deaths were from extra cardiac causes. Cardiac failure and thromboembolic or haemorrhagic complications represent the main causes of late mortality, respectively 10 and 6.7%. Twenty-one deaths were related to the prosthesis (10 thrombo-embolic accidents, 7 haemorrhagic complications and prosthesis could be discussed in 11 cases of sudden deaths and in 12 cases of death of undetermined causes. Among the 34 thrombo-embolic complications and the 13 perivalvular leakages (6 of them related to infection), 23 patients required reoperation, for valve thrombosis (14 cases with 2 deaths) or perivalvular leakage (9 cases with 2 deaths). Four other cases of valve thrombosis were treated with fibrinolytic agents with 1 death. The actuarial survival rate, hospital mortality excluded, is 69% at 10 years and 55% at 15 years.(ABSTRACT TRUNCATED AT 250 WORDS)