The EEG-inclusive home sleep test now reports on spindles per minute during nonREM sleep.
By Sree Roy
Compumedics has added a spindle density metric to the auto-generated sleep study reports of its Somfit home sleep test (HST), a frontal electroencephalography (EEG)-inclusive HST, expanding the information that sleep physicians can gain about patients’ sleep health.
In the Somfit report, the new metric appears as a single line in the sleep time statistics column—”NREM sleep spindle density”—expressed as spindles per minute during nonREM sleep. It appears alongside more common metrics like total recording time, total sleep time, REM latency, sleep latency, and wake during sleep period.
Quantifying Sleep Spindles
While the appearance of sleep spindles has typically only served as an EEG landmark for identifying N2 and N3 sleep stages, quantifying spindle density could provide sleep physicians with new insights.
Generally, higher spindle densities correlate with better sleep quality, memory consolidation, and cognitive function. Conversely, reduced spindle density may signal disorders affecting neural signal processing. Spindle density declines with age.
“It gives you a window into the nervous system in a noninvasive and relatively affordable way,” says Chris Tedor, RPSGT, Compumedics USA’s key account manager of home sleep testing (Midwest).
Potential Clinical Significance
It’s too early to know exactly how sleep physicians will incorporate the new metric into their care, if at all. However, Tedor emphasizes that a key lies in contextualizing the findings.
For example, if a patient’s study shows an apnea-hypopnea index of more than 5, and the Somfit report also reveals unexpectedly low spindle density, the added metric may provide a clue that another disorder is lurking beneath. In this case, perhaps the physician should expedite in-lab polysomnography followed by a multiple sleep latency test, or the patient should be referred to a neurologist for further evaluation.
“Consider what you’re missing right now in your patients,” Tedor says, noting that disorders ranging from depression to Alzheimer’s disease have been linked to low spindle density. “This gives you a much deeper window into flagging people in major disease states.”
Availability of Somfit Spindle Density Reporting
This week, Compumedics began launching spindle density reporting at scale in the United States. Physicians who already use Somfit and are interested in adding this capability should contact their Compumedics representative for training and activation. New purchases of Somfit will arrive with the feature already turned on.
