Over the past several years, device manufacturers have introduced a number of PFO closure devices in Europe, but conducting randomized trials to gain US market approval has proven to be a much more difficult endeavor. Companies have experienced numerous delays and setbacks in both their stroke and migraine programs. The good news: setbacks for some could also boost randomized migraine studies still ongoing by other competitors in this field.

These are tough times for companies developing PFO closure devices. Various energy-based approaches have hit the rocks, and clinical trial enrollment difficulties have derailed others. Coherex Medical hopes for better results with technology that it describes as safe, user-friendly, and more effective than competing technologies. The company's FlatStent PFO closure system combines a self-expanding stent with tissue growth materials, and a design that provides multiple means to close the PFO and thus boost the chances for long-term success.

Hopes have long been high for device innovations to treat a variety of neurological conditions ranging from stroke to migraines to depression. For all the promise these therapeutic areas hold, however, neurological device applications have proven to be among the most inscrutable for entrepreneurs and investors, replete with technological and clinical challenges. Several recent announcements have done nothing but confirm how challenging the neuro space is.