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Fig. 8 | Insights into Imaging

Fig. 8

From: Nerve entrapment syndromes of the upper limb: a pictorial review

Fig. 8

Cases of posterior interosseous nerve (PIN) pathology are illustrated: a, b Forearm ultrasound of a 58-year-old female who presented with arm pain. There is focal thickening throughout the right PIN (a, white arrows). This extends into the arcade of Frohse. This appearance can be seen with PIN syndrome. No adjacent collection or mass is identified. There was focal tenderness with transducer pressure. The left PIN is provided for comparison (b). c–e 60-year-old male who presented with progressive weakness of finger extension. Intramuscular lipoma of the supinator (blue arrow) resulted in PIN impingement at the arcade of Frohse (c). Axial T1 (c) and Axial PDFS images at the level of narrowing (d) and more distally (e), show focal thickening and hyperintensity of the PIN (c, d, white arrows). There is denervation oedema and atrophy of the extensor muscles (d, e, yellow arrows). f, g Axial PD (f) and PDFS (g) sequences with denervation oedema and atrophy of extensor muscles (white arrows) innervated by the PIN (not shown)

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