Patient (No. 1–11) and volunteer data (No. 12–23) with detailed clinical and electrophysiological findings.

<p>Hypothenar includes the following muscles: abductor digiti minimi muscle, flexor digiti minimi muscle and opponens digiti minimi muscle.</p><p>DML¹: distal-motor-latency to IOD I.</p><p>DML²: distal-motor-latency to abductor digiti minimi muscle.</p

Correlation between deep motor branch T2-signal (y-axis) and its electrical conduction time in ms (x-axis).

<p>Electrical conduction time through the deep motor branch was measured as distal motor latency to its most distal target muscle which is the first dorsal interosseus muscle (IOD I). Note how the empirical data (black dots) strongly correlate (R² = −0.8; p<0.001) in a non-linear fashion (non-linear fit of asymptotic growth, red dashed line). This finding indicates that nerve T2-signal and electrical nerve conduction show a distinctive behavior under physiological and pathological condition, in that the former exhibits its largest dynamic range near the normative reference value of dml IOD I (which is given in the literature at 3–5 ms), and that electrical conduction exhibits its largest dynamic range in severe pathological states (>5 ms). This may point toward a strong diagnostic value of nerve T2-signal as a novel marker for the early detection of nerve injury.</p

ROC plots of sensitivity versus specificity for the discrimination between GCS and healthy status.

<p>Nerve T2-signal was evaluated for its performance of diagnostic classification, empirical and fitted values are plotted. High diagnostic performance (AUC = 0.94) for nerve T2-signal of the deep motor branch was observed, while diagnostic of the ulnar nerve trunk (AUC = 0.70) and the superficial branch were significantly inferior (AUC 0.69).</p

Representative findings of nerve T2-signal increase on single subject level.

<p>one GCS patient with isolated motor symptoms (left column), another with combined motor and sensory symptoms (middle column), both compared to one asymptomatic control (right column). Three image sections from distal (A) to proximal (C) are given and image positions indicated on the anatomical schematic drawing on the left (with permission from The Journal of Bone and Joint Surgery, Volume 51, pages 1095–1103). The deep motor branch at the level of the hook of the hamate is encircled in red and found in the upper image row (A = slice position 10). Just distal to the bifurcation of the ulnar nerve motor and sensory branches are encircled in red and green, respectively (middle image row, B, slice position +3). Just proximal to the bifurction the ulnar nerve trunk is encircled in yellow (lower image row, B = slice position -3). In GCS with isolated motor symptoms (left column, GCS motor only) increased nerve T2-signal was most noticeable within the deep motor branch (red arrow) and extended over a short distance proximally into the ulnar nerve trunk (yellow circle in C), while the T2-signal was normal within the superficial sensory branch (green arrow). In case of combined motor and sensory symptoms both distal ulnar nerve branches clearly show an incresed nerve branch T2-signal (red and green circle without arrows in level B, middle column, GCS motor+sensory).</p

Patient demographics, clinical data, quantitative and qualitative imaging findings.

<p>Patient data, including age (in years), sex, time since HRS (in months), clinically and electrophysiologically affected nerve, muscle strength of affected muscles according to the MRC scale, ratio of T2- signal intensity of the peroneal and tibial nerve related to normal appearing musculature (SR), denervation pattern of target muscles at thigh and calf level, and conclusive imaging diagnosis. F: female, M; male, n.a.: not available, SR: nerve-to-muscle T2- signal intensity ratio. <b>Abbreviations:</b> atm: anterior tibialis muscle; bfm: biceps femoris muscle; edbm:extensor digitorum brevis muscle; edlm: extensor digitorum longus muscle; gm: gastrocnemius muscle; p: peroneal portion of the sciatic nerve or peroneal nerve; pbm: peroneus brevis muscle; plm: peroneus longus muscle; pom: popliteus muscle; sem: semimembranosus muscle; sn: sciatic nerve; t: tibial portion of the sciatic nerve or tibial nerve; ptm: posterior tibialis muscle.</p

Results for patients regarding the three endpoints of (i) presence of other subclinical nerve lesions, (ii) previous elbow surgery, and (iii) results of clinical follow-up.

<p>Results for patients regarding the three endpoints of (i) presence of other subclinical nerve lesions, (ii) previous elbow surgery, and (iii) results of clinical follow-up.</p

Spectrum of proximal ulnar nerve lesions.

<p>T2-w cross-sections through upper arm with ulnar nerve magnifications. [A] shows a restricted lesion involving only one individual fascicle, [B] shows multiple fascicular lesions (arrowheads) not to be confused with adjacent small vessels (v), [C] shows a whole-nerve lesion with severe caliber increase.</p

Localization and fascicular distribution of T2-nerve lesion, and denervation pattern of target muscles.

<p>siMRN in patient 5 (a, b, c: transversally orientated T2-weighted TSE with fat-suppression) and patient 7 (d: coronally orientated T2 STIR; e, f: transversally orientated T2-weighted TSE with fat-suppression). Depending on the extent of implant-related artifacts, evaluation of the sciatic nerve may be impaired or even impossible for a certain region (d). Regular depiction of the nerve roots and lumbar pexus in patient 7 (d), but the subtrochanteric sciatic nerve exhibits a peroneally accentuated T2-lesion (e), and the peroneally innervated muscles of the proximal lower leg show signs of denervation (f). In patient 5 the proximal sciatic nerve showed a T2-lesion in proximity of the ischial tuberosity (a), affecting all fascicles of the nerve at level of the hip (a) and thigh (b). Furthermore the denervation of the biceps femoris and semimembranosus muscle of the thigh (b), and the anterior tibialis, extensor digitorum, peroneus longus, popliteus and gastrocnemius muscle of the lower leg (c) indicate affection of the tibial and peroneal division of the sciatic nerve. <b>Abbreviations:</b> atm: anterior tibialis muscle; bfm: biceps femoris muscle; edlm: extensor digitorum longus muscle; gm: gastrocnemius muscle; p: peroneal portion of the sciatic nerve or peroneal nerve; plm: peroneus longus muscle; pom: popliteus muscle; sem: semimembranosus muscle; sn: sciatic nerve; t: tibial portion of the sciatic nerve or tibial nerve.</p

Typical imaging findings in healthy control, UNE and proximal ulnar nerve lesion.

<p>Upper row shows T2-w cross sections through upper arm, lower row through elbow. The first column [A and B] represents a healthy control with only slight ulnar nerve signal increase at the elbow. The second column is a typical UNE with inconspicuous ulnar nerve at upper arm level [C] and clear increase of signal and cross-sectional area at the elbow [D] (arrowheads). The third column shows a patient with atypical proximal lesion at upper arm level [E] as well as the elbow [F].</p

Constriction of the sciatic nerve by surgical material, and denervation of target muscles in patient 2.

<p>siMRN revealed compression of the peroneal portion of the left sciatic nerve by a small susceptibility prone foreign body (arrow in a). Besides denervation of the peroneally innervated muscles at the lower leg (c), denervation of the long head of the biceps femoris muscle (b) and slight denervation of the posterior tibialis muscle and the gastrocnemius muscle (c) indicated accompanying affection of the tibial nerve as well. <b>Abbreviations:</b> atm: anterior tibialis muscle; bfm: biceps femoris muscle; edlm: extensor digitorum longus muscle; gm: gastrocnemius muscle; p: peroneal portion of the sciatic nerve or peroneal nerve; plm: peroneus longus muscle; ptm: posterior tibialis muscle; sn: sciatic nerve; t: tibial portion of the sciatic nerve or tibial nerve.</p