There are two CPT codes for CDP. 92548 is for the "sensory tests", and 92549 is for both the "Sensory tests", and "motor control tests" (MCT).The 92549 code was introduced recently (i.e. about 2020). The "Sensory tests" can be (sort of) done by the "Foam and Dome" type low-budget equipment, but the MCT cannot be done without a rather expensive and complex machine. So perhaps the reason for the 92549 is to encourage use of the "real" CDP machine.
CDP is not uniformly covered by health insurance in the United States. Medicare covers it in some areas but not in others. In Illinois, Medicare does cover CDP 100% of the time. Rather peculiarly, in Illinois, Blue Cross Blue Shield generally doesn't cover posturography (about 19% of claims are paid -- depending on the type of BCBS). Cigna covers about 27% of the time, United Healthcare Medicare 100%, United Healthcare 0%.
This seems mainly to be due to purposeful omissions of coverage by these insurances, although when questioned, Insurances sometimes claim that it is "not medically necessary'. It is difficult to see why Medicare thinks CDP is medically necessary, but on the other hand, different plans within BCBS consider CDP medically necessary and others do not. It would seem more likely to us that some insurance simply covers more testing than others. The claim that it is not "medically necessary", seems to us to be a strategy to avoid coverage as well as "push back" from patients who thought they were buying full coverage health insurance. . Medicare advantage plans, often claim cover all of Medicare, usually this is just not true, and there is no insurance coverage. A type of medicare fraud, carried out by insurance companies rather than medical providers.
In our opinion, dynamic CDP (namely Equitest and very close relatives, that explicitly include motorized visual surround and platform movement, such as "Smart Balance-Master" ) should have uniform coverage by health insurance. CDP is FDA approved and has two CPT codes. It has one well documented diagnostic indication - detection of malingering (Cevette et al. 1995; Goebel et al. 1997; Krempl et al. 1998; Morgan et al. 2002). Dynamic CDP data can be pivotal in medicolegal situations as it can strongly suggest that individuals are feigning imbalance. Recently it has also become useful in identifying PPPD, a dizziness condition often combining imbalance and visual sensitivity - -the CDP machine quantifies both.
Thoughts about why insurance coverage for CDP is so sketchy.
On the other side of the issue, the use of CDP in diagnostic contexts outside that of malingering is not well established. El-Kashlan and others found CDP to be more sensitive than physical examination in distinguishing patients with vestibular disturbances from normals (El-Kashlan et al. 1998). Stewart and others suggested that CDP is as cost-effective as audiometry and ENG testing for the evaluation of vertigo (Stewart et al. 1999). However, in the authors' opinion, this conclusion differs from that of most specialists that evaluate vertigo. Dimitri and associates (Dimitri et al. 2001) found CDP of no utility in distinguishing migraine associated vertigo from Meniere's disease. Baloh and associates (Baloh et al. 1998) found CDP unable to distinguish between cerebellar and bilateral vestibular patients, a task that most neurology dizziness specialists would find quite simple.To summarize, there is presently only a small amount of data about broader diagnostic usefulness of CDP, and it is conflicted.
Another potential indication for CDP is to guide physical therapy or to document the outcome of physical therapy. While several authors suggests that it is useful in this context, (Mirka et al. 1990; Shepard 1996; El-Kashlan et al. 1998), others find it of no use in documenting functional status (O'Neill et al. 1998). Outcome studies in which therapy guided by CDP is compared to therapy without CDP are presently lacking. We would like to see more work done here.