Non-Invasive Detection of Large Vessel Occlusion in
Setting of Acute Ischemic Stroke
Francisco Gomez, MD; Jessy Walla, MD; and Fawaz Al-Mufti, MD
The authors have no actual or potential conflict of interest in relation to
the topics discussed in this column. This article may discuss non-FDA
approved devices and “off-label” uses. NCS and Currents do not endorse
any particular device.
With the recent expansion in the endovascular treatment window
for ischemic stroke, the need for improved triaging on all levels
has become most apparent. In order to maximize benefit for
our patients, the utmost celerity and accuracy must be sought.
While the stroke neurologist or neurointensivist can deftly assess
acute cerebrovascular diseases, our services are not universally
available. Furthermore, the initial evaluation is often conducted by
emergency department or emergency medical services personnel,
with an estimated 70 percent of stroke patients being initially
evaluated by EMS.
Several scales have been developed for the recognition of stroke
and have been reviewed in this column previously. However,
instruments such as the Cincinnati Prehospital Stroke Scale,
Los Angeles Motor Score, Rapid Arterial Occlusion Evaluation,
NIHSS and the Field Assessment for Emergency Destination
are not without limitations. Some may prove burdensome or
time-consuming in the field, yet others make compromises in
sensitivity or specificity. Several cohort studies concur in finding
that stroke is generally over-diagnosed in the pre-hospital setting.
The necessity for an instrument capable of delivering rapid and
highly accurate determinations becomes apparent, which this
emerging technology seeks to address.
The Cerebrotech Visor utilizes a low power electromagnetic
transceiver in a non-invasive wearable apparatus, and it detects
brain impendance changes. In short, the device generates
electromagnetic waves and measures the composition of the
intervening tissues between emitter and receiver, a process termed
volumetric electromagnetic phase-shift spectroscopy.
As fluid and brain tissue have different impedances, a
determination is made concerning fluid changes in the brain by
measuring changes in electromagnetic conductance and edema
can be measured. Early prototypes of this device were deployed in
Mexico, aiming to provide rapid triage in remote locations with no
immediate access to imaging.
The first multi-center trial, named Volumetric Integral Phaseshift
Spectroscopy for Noninvasive Detection of Hemispheric
Bioimpedance Asymmetry in Acute Brain Pathology (VITAL), is set
to conclude this coming March. Initial testing for the apparatus
showed a 93 percent sensitivity and 92 percent specificity for
stroke, with an acquisition time nearing 30 seconds. Notably, the
device was also capable of discerning small from large ischemic
strokes during testing, as noted by interhemispheric fluid
differentials, averaging 8 percent in the former, 16.5 percent in the
latter and 5 percent in the control group
Jessy Walla, MD Fawaz Al-Mufti, MD
CPSS 83% 69%
FAST 85% 68%
LAPSS-2000 49% 97%
MASS 63% 94%
NIHSS 90% 45%
VEPS 93% 92%