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A Systematic Review of Hyperselective Neurectomy (HSN) for Management of the Spastic Upper Limb
Sam J Stuart, BS
1, Carlos R Martinez, MD, MPH
2; Joshua M Adkinson, MD
3(1)Indiana University School of Medicine - Terre Haute, Terre Haute, IN, (2)Indiana University School of Medicine, Indianapolis, IN, (3)Division of Plastic Surgery, Indiana University School of Medicine, Indianapolis, IN
Introduction: Upper limb spasticity is a common sequela of upper motor neuron lesions, especially cerebral palsy, stroke, and traumatic brain injury. When conservative measures such as botulinum toxin or orthoses fail, surgical intervention may be indicated. Hyperselective neurectomy (HSN) is a microsurgical technique whereby a precise amount of terminal motor fascicles are resected with the goal of reducing spasticity while preserving function. Although used with increasing frequency, studies reporting outcomes are limited. This systematic review assesses outcomes of HSN for upper limb spasticity, with a focus on spasticity reduction, muscle strength, and functional range of motion (ROM).
Materials and Methods: A systematic review was conducted in accordance with PRISMA guidelines across Ovid MEDLINE, Embase, and SCOPUS databases through March 2025. Included studies reported clinical outcomes of HSN performed for upper limb spasticity involving the shoulder, elbow, forearm (pronators), wrist, or fingers. Data extracted included spasticity (Modified Ashworth Scale [MAS], Tardieu T scores), strength (Medical Research Council [MRC] scale), and active/passive ROM. Studies were stratified by anatomical region.
Results: Eleven studies (n=224 patients, 290 HSNs) met inclusion criteria. Spasticity etiologies included cerebral palsy (46%), stroke (30%), and traumatic brain injury (8%). All targeted regions showed postoperative reductions in spasticity. MAS reductions were most pronounced in the elbow and forearm, with mean postoperative scores <1 in 5 of 6 elbow studies. HSN of forearm pronators achieved complete resolution of spasticity in 2 of 4 studies. Muscle strength was generally preserved or improved; transient weakness was rare and self-resolving. ROM outcomes varied, with moderate improvements observed for active elbow flexion (up to +33°) and supination (up to +43°). Slight recurrence of spasticity was frequently reported among studies with longitudinal follow-up, but this did not reach statistical significance (mean recurrence +0.2 to +0.5 MAS points). Complications were infrequent and mild, including isolated cases of wound infection and transient paresis.
Conclusions: HSN provides consistent short- and medium-term reductions in upper limb spasticity while preserving or modestly enhancing voluntary motor function. While current data supports its safety and efficacy, data interpretation is limited by small, heterogeneous case series with variable resection thresholds and outcome measures. Prospective, multicenter studies with standardized protocols are needed to define optimal fascicle selection, quantify long-term recurrence risk, and establish best practices.
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