title: Sensory nerve cross-anastomosis and electrical muscle stimulation synergistically enhance functional recovery of chronically denervated muscle.
abstract: BACKGROUND
  Long-term muscle denervation leads to severe and irreversible atrophy coupled with loss of force and motor function. These factors contribute to poor functional recovery following delayed reinnervation. The authors' previous work demonstrated that temporarily suturing a sensory nerve to the distal motor stump (called sensory protection) significantly reduces muscle atrophy and improves function following reinnervation. The authors have also shown that 1 month of electrical stimulation of denervated muscle significantly improves function and reduces atrophy. In this study, the authors tested whether a combination of sensory protection and electrical stimulation would enhance functional recovery more than either treatment alone.
  
  
  METHODS
  Rat gastrocnemius muscles were denervated by cutting the tibial nerve. The peroneal nerve was then sutured to the distal tibial stump following 3 months of treatment (i.e., electrical stimulation, sensory protection, or both). Three months after peroneal repair, functional and histologic measurements were taken.
  
  
  RESULTS
  All treatment groups had significantly higher muscle weight (p<0.05) and twitch force (p<0.001) compared with the untreated group (denervated), but fiber type composition did not differ between groups. Importantly, muscle weight and force were significantly greater in the combined treatment group (p<0.05) compared with stimulation or sensory protection alone. The combined treatment also produced motor unit counts significantly greater than sensory protection alone (p<0.05).
  
  
  CONCLUSIONS
  The combination treatment synergistically reduces atrophy and improves reinnervation and functional measures following delayed nerve repair, suggesting that these approaches work through different mechanisms. The authors' research supports the clinical use of both modalities together following peripheral nerve injury.
authors.affiliation: Hamilton, Ontario, Canada From the School of Biomedical Engineering, the Department of Psychiatry and Behavioural Neurosciences, and the Department of Surgery, Division of Plastic Surgery, McMaster University.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Willand
authors.forename: Michael
authors.initials: M
authors.lastname: Holmes
authors.forename: James R
authors.initials: JR
authors.lastname: Bain
authors.forename: Hubert
authors.initials: H
authors.lastname: de Bruin
authors.forename: Margaret
authors.initials: M
authors.lastname: Fahnestock
mesh_terms: D000704:Analysis of Variance; D000714:Anastomosis, Surgical / Q000379:methods; D000818:Animals; D001707:Biopsy, Needle; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods; D005835:Genitalia; D007150:Immunohistochemistry; D008297:Male; D009121:Muscle Denervation / Q000379:methods; D009133:Muscular Atrophy / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D009416:Nerve Regeneration / Q000502:physiology*; D010543:Peroneal Nerve / Q000473:pathology / Q000601:surgery*; D011897:Random Allocation; D051381:Rats; D011917:Rats, Inbred Lew; D020127:Recovery of Function; D013979:Tibial Nerve / Q000473:pathology / Q000601:surgery*