SLAD-R (Selective Laryngeal Adductor Denervation-Reinnervation)

MS ENT University Exam Answer - 10 Marks

Definition / Introduction

• Developed by Dr. Gerald Berke at UCLA in the late 1990s
• First reported in 1999 (Berke GS et al., Annals of Otology, Rhinology & Laryngology)
• Provides long-term, potentially permanent relief from the voice breaks of ADSD

Background: Why SLAD-R was Developed

• A focal laryngeal dystonia causing involuntary hyperadduction of the vocal folds during phonation
• Results in strained, strangled voice with characteristic voice breaks (especially on voiced consonants)
• The RLN drives hyperadductory activity via the thyroarytenoid (TA) and lateral cricoarytenoid (LCA) muscles

Anatomy Relevant to the Procedure

• Anterior (adductor) branch - supplies TA and LCA muscles (main targets)
• Posterior (abductor) branch - supplies posterior cricoarytenoid (PCA), left untouched

Surgical Technique (Step-by-step)

• General anesthesia with EMG-enabled endotracheal tube (NIM-Response System) to monitor RLN activity intraoperatively
• Neck extended with shoulder roll; surgeon stands at head of bed
• IV dexamethasone (10 mg) + prophylactic antibiotics given before incision

1. Skin incision - horizontal neck incision in a skin crease (similar to thyroid surgery approach)
2. Exposure - subplatysmal flaps raised; strap muscles retracted to expose the thyroid cartilage and trachea
3. Identification of the RLN - traced in the tracheoesophageal groove to the point where it branches near the cricothyroid joint
4. Selective identification of the adductor branch - the anterior (adductor) branch supplying TA and LCA is identified under magnification, confirmed by EMG monitoring
5. Denervation - the adductor branches of the RLN are transected bilaterally; the abductor branch (to PCA) is carefully preserved to maintain normal breathing/abduction
6. LCA myotomy - a partial myotomy of the lateral cricoarytenoid muscle may be performed (conservative LCA myotomy has been shown to reduce postoperative breathiness)
7. Reinnervation - a branch of the ansa cervicalis nerve is harvested and anastomosed (sutured) to the distal cut stump of the adductor branch of the RLN
   • This prevents muscle atrophy
   • Provides passive, non-voluntary muscle tone
   • Critically, prevents spontaneous reinnervation by the proximal dystonic RLN stump
8. Wound closure in layers

Rationale for Bilateral Surgery

• Adductor SD involves bilateral hyperadduction
• Unilateral RLN section alone (Dedo) gave temporary benefit but bilateral dystonia returns
• Bilateral selective denervation + ansa reinnervation addresses both vocal folds simultaneously
• The ansa cervicalis restores resting tone without re-establishing the dystonic reflex arc

Postoperative Course

• Patients must be counseled that a breathy voice lasting 3+ months is expected and normal
• This is the most important and challenging aspect of patient counseling

Results / Outcomes

• Initial series (21 patients, 1999): 19/21 patients had absent to mild voice breaks postoperatively; only 1 required subsequent Botox
• Long-term follow-up (81 patients, mean 49 months):
  • 83% had significantly improved Vocal Handicap Index-10 (VHI-10) scores
  • 91% said their post-surgical voice was more fluent than their best post-Botox voice
  • 82% would recommend the surgery to others
• Outcomes with SLAD-R are comparable to Botox when performed by experienced surgeons (Cummings Otolaryngology)

Complications

Comparison: SLAD-R vs. Botox (Examiner's Favorite Table)

Patient Selection / Indications

• Confirmed diagnosis of Adductor Spasmodic Dysphonia (ADSD)
• Failed or intolerant of repeated Botox injections
• Motivated patient willing to accept 3-6 month period of breathy voice
• Younger patients who find repeated injections difficult to manage
• Normal laryngeal anatomy (no structural abnormality)

• Abductor SD (different pathophysiology)
• Patient unable to tolerate general anesthesia
• Unrealistic voice expectations

Key Points to Remember for Exam

1. SLAD-R = Selective adductor denervation (RLN anterior branch) + Reinnervation with ansa cervicalis
2. Introduced by Berke et al., 1999, UCLA
3. Addresses the problem of spontaneous reinnervation that caused Dedo's RLN section to fail
4. The ansa cervicalis provides passive tone without dystonic impulses
5. Bilateral procedure; posterior branch (PCA) is preserved
6. Post-op breathiness for 3+ months is expected - not a complication
7. 83-91% long-term success rates
8. Recurrence rate ~11%; responds to Botox
9. Only a few centers worldwide perform this surgery