Postpartum reverse-Takotsubo from pheochromocytoma diagnosed by bedside point-of-care ultrasound: A case report.

Point-of-care ultrasound is invaluable in the setting of obstetric anesthesia, where the differential diagnosis for dyspnea, hypoxemia and/or hemodynamic abnormalities is broad. This report describes a previously apparently healthy parturient with an uncomplicated pregnancy at 35-weeks gestation who underwent an emergency cesarean section under general anesthesia due to severe acute abdominal pain and fetal bradycardia. Intraoperatively, she presented with severe hypertension and tachycardia that were difficult to control and associated with ischemic ECG changes. In the immediate postoperative period, she developed retrosternal tightness and dyspnea, and a bedside point-of-care ultrasound scan revealed a grossly dilated and hypokinetic left ventricle, as well as diffuse B-lines throughout all lung fields - consistent with cardiogenic pulmonary edema. She was admitted to the intensive care unit, where she recovered over several days. Pheochromocytoma was subsequently diagnosed, and she eventually underwent uneventful elective adrenalectomy after appropriate endocrine and hemodynamic optimization.

Applying functional MRI to the spinal cord and brainstem.

Functional magnetic resonance imaging of the spinal cord (spinal fMRI) has facilitated the noninvasive visualization of neural activity in the spinal cord (SC) and brainstem of both animals and humans. This technique has yet to gain the widespread usage of brain fMRI, due in part to the intrinsic technical challenges spinal fMRI presents and to the narrower scope of applications it fulfills. Nonetheless, methodological progress has been considerable and rapid. To date, spinal fMRI studies have investigated SC function during sensory or motor task paradigms in spinal cord injury (SCI), multiple sclerosis (MS) and neuropathic pain (NP) patient populations, all of which have yielded consistent and sensitive results. The most recent study in our laboratory has successfully used spinal fMRI to examine cervical SC activity in a SCI patient with a metallic fixation device spanning the C(4) to C(6) vertebrae, a critical step in realizing the clinical utility of the technique. The literature reviewed in this article suggests that spinal fMRI is poised for usage in a wide range of patient populations, as multiple groups have observed intriguing, yet consistent, results using standard, readily available MR systems and hardware. The next step is the implementation of this technique in the clinic to supplement standard qualitative behavioral assessments of SCI. Spinal fMRI may offer insight into the subtleties of function in the injured and diseased SC, and support the development of new methods for treatment and monitoring.

In contrast to BOLD: signal enhancement by extravascular water protons as an alternative mechanism of endogenous fMRI signal change.

Despite the popularity and widespread application of functional magnetic resonance imaging (fMRI) in recent years, the physiological bases of signal change are not yet fully understood. Blood oxygen level-dependant (BOLD) contrast - attributed to local changes in blood flow and oxygenation, and therefore magnetic susceptibility - has become the most prevalent means of functional neuroimaging. However, at short echo times, spin-echo sequences show considerable deviations from the BOLD model, implying a second, non-BOLD component of signal change. This has been dubbed "signal enhancement by extravascular water protons" (SEEP) and is proposed to result from proton-density changes associated with cellular swelling. Given that such changes are independent of magnetic susceptibility, SEEP may offer new and improved opportunities for carrying out fMRI in regions with close proximity to air-tissue and/or bone-tissue interfaces (e.g., the prefrontal cortex and spinal cord), as well as regions close to large blood vessels, which may not be ideally suited for BOLD imaging. However, because of the interdisciplinary nature of the literature, there has yet to be a thorough synthesis, tying together the various and sometimes disparate aspects of SEEP theory. As such, we aim to provide a concise yet comprehensive overview of SEEP, including recent and compelling evidence for its validity, its current applications and its future relevance to the rapidly expanding field of functional neuroimaging. Before presenting the evidence for a non-BOLD component of endogenous functional contrast, and to enable a more critical review for the nonexpert reader, we begin by reviewing the fundamental principles underlying BOLD theory.