BACKGROUND: The surgical treatment of spontaneous posterior interosseous nerve (PIN) palsy with hourglass-like fascicular constriction (HLFC) remains controversial.
OBJECTIVE: To review 41 patients with complete spontaneous PIN palsy with HLFC to clarify the necessity and choice of surgery.
METHODS: Interfascicular neurolysis (NY), neurorrhaphy, and autografting were performed on 10, 8, and 6 patients, respectively. The thinning extent of a nerve fasciculus ≤0.25, 0.25 to 0.75, and ≥0.75 was defined as mild, moderate, and severe constriction, respectively. Final British Medical Research Council muscle power grade ≥4 was defined as good recovery.
RESULTS: Ultrasound showed the number, location, and thinning extent of HLFC of PIN well, with results that were highly consistent with intraoperative measurements. Of the 17 conservatively treated patients, 13 recovered well. Of the 24 surgically treated patients, 20 recovered well. For NY, 8 patients with mild to moderate PIN constriction recovered well, but 2 patients with severe PIN constriction recovered poorly. For 16 patients with severe HLFC, 12 of 14 patients who underwent neurorrhaphy or autografting recovered well; the surgical effects were much better than those of 2 patients who had undergone NY.
CONCLUSION: Ultrasound is a helpful diagnostic technique for spontaneous PIN palsy with HLFC. Surgery is necessary for PIN constriction if conservative treatments fail. Surgical choices depend largely on the thinning extent of the PIN constriction and the age of the patients. The outcomes of patients aged ≥50 years were much worse. We suggest NY for mild to moderate, and neurorrhaphy or autografting for severe PIN constriction.
ABBREVIATIONS: APL, abductor pollicis longus
CMAP, compound muscle action potential
EDC, extensor digitorum communis
EPL, extensor pollicis longus
HLFC, hourglass-like fascicular constriction
MRC, Medical Research Council muscle power grade
MUP, motor unit potential
NAP, nerve action potential
PIN, posterior interosseous nerve