Objective:

To identify variables in Transcranial Doppler (TCD) that may predict sleep disordered breathing.

Background:

Sleep-related breathing disorders, such as obstructive sleep apnea (OSA), are common after acute ischemic stroke. The presence and severity of this disorder is associated with poorer outcomes in the stroke population. Several questionnaire-based screening tools for OSA exist but have many limitations. Clinical observation suggests that a sawtooth pattern of velocity fluctuations seen on transcranial dopplers (TCD) of the middle cerebral artery (MCA) may be associated with clinical correlates of sleep apnea, such as hypercarbia during apnea.

Design/Methods:

We retrospectively reviewed a prospectively collected cohort of 26 subjects (19 confirmed stroke, 3 TIA, 4 other), who received TCD with emboli monitoring of the bilateral MCAs for 20 minutes, as part of an embolic stroke of unknown source (ESUS) evaluation. Each patient had been flagged for suggestive features of sleep apnea, such as sawtooth patterns showing increased velocity fluctuations. We collected baseline demographic data and the velocity differences between nadir and apex above a threshold of 10 cm/sec. These were compared to 50 control subjects who also underwent TCD emboli monitoring.

Results:

Only one of the 26 patients had been previously diagnosed with OSA per polysomnography. When compared to controls, TCDs of patients with suspected OSA appear to show greater velocity fluctuations. Data evaluation is ongoing.

Conclusions:

Measurement of TCD wave frequency and amplitude is feasible when sawtooth patterns are present. This suggests a more dynamic vasomotor response, possibly relating to increased hypercarbia during apnea and hypopnea. Further research may demonstrate increased utility of TCD for targeted screening for sleep apnea.