Reasons to Monitor. Intraoperative Laryngeal Nerve Monitoring 10/24/2008. Cranial Nerve Monitoring. Otologic and Neurotologic surgery: the norm

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1 Head and Neck Endocrine Surgery Course October 24-25, 2008 San Francisco Cranial Nerve Monitoring Intraoperative Laryngeal Nerve Monitoring Lisa A. Orloff, M.D. Department of Otolaryngology/Head & Neck Surgery University of California, San Francisco Otologic and Neurotologic surgery: the norm Parotid Surgery: common Thyroid/parathyroid surgery: growing awareness/use Reasons to Monitor 1. Aid in identification of RLN (speed, accuracy) 2. Aid in dissection (or avoidance) of RLN 3. Neural prognostic evaluation during and at end of surgery (avoid bilateral VC paralysis) RLN (vocal fold) Paralysis Dralle et al, Surgery 2004: 29,998 nerves at risk: no SS difference in paralysis rates between visual nerve ID only vs. RLNM 0.84% permanent RLN paralysis (historically 1-3%) Visual nerve identification = gold standard For low volume surgeons (<45/year), but not for high volume surgeons, RLNM reduced permanent RLNP rate (1.06% overall) Difficult to demonstrate a difference given low overall rate of RLNP RLNM is a promising tool for nerve identification and protection 1

2 RLNM: Updated Evidence-Based Assessment Dralle et al, World J Surg 2008: 6 studies with > 100 NAR each, RLNM vs. visual ID only: permanent RLNP tended to be lower with IONM (not SS), rates ranged from 0-11% RLNP rates are so low that prohibitively large numbers of pts need to achieve statistical power No prospective multicenter trial, as no one willing to accept randomization to a non-ionm control group Intraoperative Nerve Monitoring Exploding Myths Use of laryngeal nerve monitoring does not suggest that one doesn t know how to find the nerves without it Even if one has been performing thyroid surgery successfully, adding monitoring can provide useful information Intraoperative Nerve Monitoring - Myths Whether to Monitor? Improved patient outcomes Conversely, use of nerve monitoring is not a substitute for careful dissection and a cautious approach to identifying the laryngeal nerves Surgeon and patient peace of mind In case of injury, you ve used the available safety-minded technology Question is not should we monitor,but HOW to monitor 2

3 Importance of laryngoscopy Pre- and post-op laryngeal exam goes hand-inhand with IONM and is ESSENTIAL IN ALL CASES Informs surgeon of his or her technique Represents the only objective, accurate outcome measure Well-known lack of relation between vocal symptoms and glottic function Flynn Am J Surg 1994; Levin 1992; Steurer Laryngoscope 2002 Preoperative laryngoscopy Establish baseline function Operative planning and recognition of disease aggression Patient counseling Management of the nerve found invaded depends on preop functional status Falk 95 Symptomatic assessment is unreliable due to variation in vocal cord position and contralateral cord compensation Flynn 94, Cunning 55, Huppen 56 Postoperative laryngoscopy Advantage to patient requiring future cervical surgery Informs patient re possible aspiration Those with superior results report them. Rates of VCP for expert surgeons are low, but many reports in the 6-8% exist, some as high as 23%. Tsang 98, Cohn 94,Wanebo 98, Wilson 71,Wanger 94, Samaan 83 3

4 Indications for Laryngeal Nerve Monitoring 1. Malignancy 2. Concomitant lymph node dissection 3. Graves disease and/or thyroiditis 4. Substernal goiter 5. Revision surgery 6. Surgery after XRT 7. Only one functioning RLN 8. Any case of bilateral surgery 9. All cases State-of-the-Art Noninvasive Monitoring Surface electrodes: Postcricoid PCA monitoring Endotracheal tube-based TA monitoring Passive and evoked EMG Postcricoid PCA monitoring Equally sensitive, reliable, and safe to ETT +: ease of placement, low cost, commercial availability -: does require 2 nd laryngoscopy Better to insert PCA electrodes before intubation Endotracheal tube-based monitoring Low pressure cuffed ET tube with integrated wire electrodes, insulated except for 30 mm at glottic level Left and right electrode pairs skewed anteriorly for optimal VC contact ETT cuff in lower subglottis/proximal trachea 4

5 Nerve Integrity Monitoring System EMG electrode endotracheal tube NIM 2 (Medtronic) oscilloscope with audio Ground and stimulator anode surface electrodes Hand-held pulse generator Probes and Electrodes Probe: stimulates nerves Electrodes: "listen" for a response EMG Intubation with nerve-monitoring tube Short-acting, nondepolarizing agent (succ) No long-term paralytic or local anesthetic agents Visualize electrode/vc contact If using postcricoid electrode, place it first Electromyography Measurement of Muscle Activity Audio supplement to visual EMG display on monitor 5

6 Intubation (cont.) Electrode Placement Proper Position Ground, recording, stimulator electrodes to shoulder, all electrodes to box May need to rotate tube clock/counterclockwise Position patient before taping tube Witness normal respiratory EMG activity (30-70 uv) as succ wears off Choose event threshold 100 uv Stim at ma RLN Injury during Thyroidectomy Stretch/traction, pressure, crush, electrical injury, ischemia, suction injury all without transection all invisible to the surgeon s eye RLN Injury during Thyroidectomy Surgeons significantly underestimate RLN injury Electrical testing is better than visual inspection If unilateral RLN injury is detected, bilateral surgery may be delayed Lo C-Y et al, Arch Surg 2000 : 6.6% VCP by postop lx exam; only 1.1% of injured nerves were recognized visually during surgery 6

7 Stimulation Technique Dry environment is best Place probe perpendicular to tissue Hold probe on for at least 1S Set stimulus level based on specific procedure needs Stimulus = 0.40 ma Threshold = 100 uv EMG RESPONSE 120 uv Beep Beep Rules of Thumb Prognostic Function Don t regard a negative response to stimulation as a true negative until a true positive has been identified Use lx palpation to confirm/backup EMG Repetitive passive EMG activity may indicate injury, or lightening of anesthesia At end of procedure, stim at 0.4 ma predicts normal RLN function postop Randolph, Normative Data Total pts =1086, NAR=1430, thyroid surgery EMG analysis All pts-normal larynx exam post 1 ma 7

8 Summary IONM and Thyroidectomy Can be a noisy surgery EMG Tube placement is essential Monitoring Goals: Identify the nerve(s) Control manipulation during dissection Verify integrity: Prior to other side or closing Stimulus: ma Threshold: 100µV Applications of Laryngeal Nerve Monitoring Thyroid surgery Parathyroid surgery Zenker s diverticulum surgery Carotid endarterectomy Esophagectomy Laryngotracheal stenosis surgery Anterior approach to cervical spine Skull base procedures Chest procedures Thank you Consider whether to insert videos of vcp probably not as Courey will show 8

9 World J Surg Jul;32(7): Related Articles, Links Intraoperative monitoring of the recurrent laryngeal nerve in thyroid surgery. Dralle H, Sekulla C, Lorenz K, Brauckhoff M, Machens A; German IONM Study Group.Collaborators (11) Blankenburg Ch, Ground S, Hamelmann W, Heidemann H, Koch B, Kruse E, Lehmann D, Müller N, Szelenyi A, Timmermann W, Wenner F. Department of General, Visceral and Vascular Surgery, Martin-Luther-University of Halle, Ernst-Grube-Str. 40, D Halle/Saale, Germany. henning.dralle@medizin.uni-halle.de BACKGROUND: Recurrent laryngeal nerve (RLN) palsy ranks among the leading reasons for medicolegal litigation of surgeons because of its attendant reduction in quality of life. As a risk minimization tool, intraoperative nerve monitoring (IONM) has been introduced to verify RLN function integrity intraoperatively. Nevertheless, a systematic evidence-based assessment of this novel health technology has not been performed. METHODS: The present study was based on a systematic appraisal of the literature using evidence-based criteria. RESULTS: Recurrent laryngeal nerve palsy rates (RLNPR) varied widely after thyroid surgery, ranging from 0%-7.1% for transient RLN palsy to 0%-11% for permanent RLN palsy. These rates did not differ much from those reported for visual nerve identification without the use of IONM. Six studies with more than 100 nerves at risk (NAR) each evaluated RLNPR by contrasting IONM with visual nerve identification only. Recurrent laryngeal nerve palsy rates tended to be lower with IONM than without it, but this difference was not statistically significant. Six additional studies compared IONM findings with their corresponding postoperative laryngoscopic results. Those studies revealed high negative predictive values (NPV; 92%-100%), but relatively low and variable positive predictive values (PPV; 10%-90%) for IONM, limiting its utility for intraoperative RLN management. CONCLUSIONS: Apart from navigating the surgeon through challenging anatomies, IONM may lend itself as a routine adjunct to the gold standard of visual nerve identification. To further reduce the number of false negative IONM signals, the causes underlying its relatively low PPV require additional clarification. Surgery Dec;136(6): Related Articles, Links Risk factors of paralysis and functional outcome after recurrent laryngeal nerve monitoring in thyroid surgery. Dralle H, Sekulla C, Haerting J, Timmermann W, Neumann HJ, Kruse E, Grond S, Mühlig HP, Richter C, Voss J, Thomusch O, Lippert H, Gastinger I, Brauckhoff M, Gimm O. Department of General, Visceral and Vascular Surgery, Klinikum Kröllwitz, University of Halle, Ernst-Grube-Strasse 40, D Halle, Germany. BACKGROUND: Recurrent laryngeal nerve monitoring (RLNM) has been suspected to reduce postoperative RLN paralysis (RLNP). However, functional outcome of RLNM in comparison with no nerve identification and visual nerve identification only has not been analyzed. METHODS: Analysis of 16,448 consecutive multi-institutional operations resulted in 29,998 nerves at risk. Three groups of different RLN treatment were compared: group 1, no RLN identification; group 2, visual RLN identification; and group 3, visual RLN identification and electromyographic monitoring. RLNM was performed with a bipolar needle electrode that was placed through the cricothyroid ligament into the vocal muscle. RESULTS: Risk factors for permanent RLNP were recurrent benign and malignant goiter (odds ratios, [ORs]), 4.7, and 6.7, respectively), primary surgery in thyroid malignancy (OR, 2.0), lobectomy (OR, 1.8), no nerve identification (OR, 1.4), low or medium volume hospital (OR, 1.3), and low volume surgeons (OR, 1.2). CONCLUSIONS: Based on these data, visual nerve identification was identified to be the gold standard of RLN treatment in thyroid surgery. RLNM is a promising tool for nerve identification and protection in extended thyroid resection procedures. However, because of the overall low frequency of RLNP, no statistical difference compared with visual nerve identification only was reached in the setting of this study. Langenbecks Arch Surg Nov;389(6): Epub 2004 Jan 13. Related Articles, Links Validity of intra-operative neuromonitoring signals in thyroid surgery. Thomusch O, Sekulla C, Machens A, Neumann HJ, Timmermann W, Dralle H. Department of General, Visceral and Vascular Surgery, Martin Luther University of Halle- Wittenberg, Halle, Germany. o.thomusch@gmx.de BACKGROUND: Although intra-operative neuromonitoring (IONM) is widely used in thyroid surgery, the validity of the received IONM signals are still unknown. METHOD: Prospective collection of data forms in 29 hospitals from 8,534 patients with 15,403 nerves at risk, who underwent surgery for benign and malignant goitre disorders between August 1999 and January IONM was performed by indirect stimulation via the vagal nerve and by direct recurrent laryngeal nerve (RLN) stimulation in 12,486 cases. IONM signals were compared with early (<14 days) and late (6 months) postoperative vocal cord function findings. RESULTS: The transient and permanent RLN palsy rate was 2.8% and 0.7%, respectively. Monitoring of the RLN function was significantly more reliable via the indirect IONM stimulation route than via the direct IONM stimulation route (specificity P<0.05). IONM by indirect stimulation via the vagal nerve reliably excluded postoperative, permanent, vocal cord palsy (specificity 97.6%, negative predictive value 99.6%). However, a changed IONM was insufficient to predict permanent RLN palsy (sensitivity 45.9%, positive predictive value 11.6%). IONM was not associated with increased general morbidity. CONCLUSIONS: For intra-operative neuromonitoring, indirect stimulation of the RLN is superior to direct stimulation. An intact acoustic IONM signal is highly predictive of intact postoperative RLN function. When the IONM signal is abnormal or absent, a one-stage extensive thyroid resection should be performed only if the surgeon is absolutely convinced that the first RLN is not harmed or a total thyroidectomy is mandatory. 9