The Ultrasound pattern sum score - UPSS. A new method to differentiate acute and subacute neuropathies using ultrasound of the peripheral nerves

•The recently described ultrasound findings in several neuropathies of heterogeneous origin make classification with pattern analysis necessary.•The ultrasound pattern sum score (UPSS) and its sub-scores UPS-A, -B and -C enable a differentiation of several acute and subacute axonal and demyelinating neuropathies.•Enlarged cervical nerve roots and/or the vagus without or with only slight enlargement of the peripheral nerves enable a differentiation from GBS and subacute onset CIDP.

ObjectiveUltrasound differentiation of neuropathies is a great challenge. We, therefore, suggest a standardized score to operationalize differentiation between several acute and subacute onset neuropathies.MethodWe retrospectively analyzed the ultrasound data of 61 patients with acute or subacute neuropathies, e.g. chronic immune-mediated neuropathies, Guillain-Barré syndrome (GBS), and axonal/vasculitic neuropathies. We compared these data to 28 healthy controls. Based on these results an ultrasound pattern sum score (UPSS) with three sub-scores (UPS-A for the sensorimotor nerves, UPS-B for the cervical roots and the vagal nerve and UPS-C for the sural nerve) was developed. Afterwards, the applicability of the score was prospectively validated in 10 patients with chronic neuropathies and in 14 patients with unknown acute and subacute PNP before performing additional tests.ResultsUPS-A and UPSS were significantly higher in CIDP than in other neuropathies and controls (p < 0.001). UPS-B was significantly more often pathologic in GBS than in CIDP and other neuropathies (p < 0.001). Using receiver operation characteristics curve analysis boundary values for each score were defined. Positive predictive value (PPV) of these scores for CIDP and GBS was >85%. Vasculitic neuropathies showed an intermediate type of UPSS compared to other axonal neuropathies (p < 0.001). In the prospective application the pattern score could be used with good accuracy in several types of neuropathy.ConclusionUPS-A and UPSS operationalize to diagnose acute and subacute-onset CIDP and its variants with high sensitivity, specificity, and PPV. An increased UPS-B with normal UPSS and other sub scores may point to the diagnosis of GBS with high PPV and enables the differentiation from CIDP.SignificanceUsing the UPSS and its sub-scores gives a new diagnostic power to the method of the peripheral nerve ultrasound.