Description of Event or Problem · 1
AN ARTICLE TITLED ¿VAGUS NERVE STIMULATION AFTER LEAD REVISION¿ WAS RECEIVED AND REVIEWED BY THE MANUFACTURER. THE AUTHORS REVIEWED ALL VNS LEAD REVISIONS PERFORMED BETWEEN OCTOBER 2001 AND AUGUST 2011 AT THE UNIVERSITY OF HOSPITALS AND CLINICS. TWENTY-FOUR PATIENTS UNDERWENT 25 LEAD REVISIONS. IN ALL CASES, THE HELICAL ELECTRODES WERE REMOVED, AND A NEW LEAD WAS PLACED ON THE PREVIOUSLY USED SEGMENT OF VAGUS NERVE. ALL INPATIENT AND OUTPATIENT RECORDS OF THE 25 LEAD REVISIONS WERE RETROSPECTIVELY REVIEWED. ALL PATIENTS WERE TREATED BY A SINGLE NEUROSURGEON. TWENTY-FOUR PATIENTS UNDERWENT 25 VNS REVISIONS BETWEEN OCTOBER 2001 AND AUGUST 2011. OF THESE 25 REVISIONS, 4 WERE SECOND AND 21 WERE FIRST LEAD REVISIONS. ¿THE PATIENTS IN 18 CASES (72%) PRESENTED WITH HIGH IMPEDANCE AT THE TIME OF REVISION, 2 CASES (8%) INVOLVED A SHORT CIRCUIT WITHIN THE SYSTEM, 4 CASES (16%) DEMONSTRATED NORMAL IMPEDANCE, AND 1 CASE (4%) HAD NO IMPLANTED VNS SYSTEM AND THEREFORE NO IMPEDANCE READING SINCE THE SYSTEM HAD BEEN PREVIOUSLY REMOVED AT ANOTHER INSTITUTION BECAUSE OF INFECTION.¿ ¿SIXTEEN (64%) OF THE 18 CASES WITH HIGH IMPEDANCE AT THE TIME OF REVISION HAD NO VISIBLE DAMAGE OR FRACTURE WITHIN THE LEAD AND/OR CABLE, SUGGESTING AN INTRINSIC LESION WITHIN THE LEAD AND/OR CABLE. OTHER CAUSES OF LEAD FAILURE INCLUDED VISIBLE FRACTURES OF THE LEAD IN 3 CASES (12%), INCREASING SEIZURE FREQUENCY AND AN IMPEDANCE INDICATING A SHORT CIRCUIT IN 2 CASES (8%), NORMAL IMPEDANCE BUT PAIN AND SHOCK-LIKE SENSATIONS SUSPECT FOR DEVICE MALFUNCTION IN 2 CASES (8%), ELECTRODE COIL DISLOCATION FROM THE VAGUS NERVE IN 1 CASE (4%), AND A PREVIOUS HARDWARE INFECTION AND VNS SYSTEM REMOVAL IN 1 CASE (4%).¿ SYMPTOMS VARIED DEPENDING ON THE ETIOLOGY OF LEAD FAILURE. THE PATIENTS IN 18 CASES (72%) PRESENTED WITH INCREASED SEIZURE FREQUENCY; IN 4 CASES (16%), WITH NECK AND/OR CHEST PAIN, PARESTHESIAS, OR SHOCK-LIKE SENSATIONS¿ ALL PROBABLY THE RESULT OF A SHORT CIRCUIT WITHIN THE SYSTEM; AND IN 6 CASES (24%), WITH NO NEW SYMPTOMS. ADDITIONALLY, 3 CASES (12%) HAD A HISTORY OF VNS-RELATED INFECTION, AND 3 CASES (12%) HAD A RECENT HISTORY OF HEAD AND/OR NECK TRAUMA.¿ DURING LEAD REVISION SURGERY IN ALL CASES, THE VAGUS NERVE WAS FOUND ENCASED IN FIBROUS SCAR TISSUE WHICH WAS SURGICALLY DISSECTED. THERE WERE NO POSTOPERATIVE INFECTIONS. ¿ONLY 1 PATIENT EXPERIENCED A COMPLICATION REQUIRING ADDITIONAL SURGERY; IN THIS PATIENT THE LEAD CABLE WAS TAUT, CREATING A PULLING SENSATION ON NECK TURNING." IN CONCLUSION, THE AUTHORS ¿FOUND THAT LEAD FAILURE OCCURS FOR A VARIETY OF REASONS AND IN OUR SERIES WAS MOST COMMONLY OBSERVED IN CASES OF HIGH IMPEDANCE WITHIN THE VNS LEAD, WHICH WAS FOUND IN 72% OF [THE] LEAD REVISIONS. THE MAJORITY OF PATIENTS (89%) WHO PRESENTED WITH HIGH IMPEDANCE HAD NO VISIBLE DAMAGE OR GROSS FRACTURE OF THE LEAD OR CABLE. THE ETIOLOGY OF HIGH IMPEDANCE AND LEAD FAILURE IS NOT ENTIRELY CLEAR IN THESE CASES.¿ IT WAS FOUND THAT THE ¿PLACEMENT OF A NEW VNS LEAD AT THE PREVIOUSLY USED SEGMENT OF VAGUS NERVE PROVIDED A PROPER CONTACT IN ALL 16 SUCH CASES AS WELL AS NORMAL IMPEDANCE, IMPLYING THAT THE PRESENCE OF DENSE SCAR TISSUE WAS PROBABLY NOT THE CAUSE OF LEAD FAILURE.¿ ¿IN ADDITION TO AN INTRINSIC INCREASE IN LEAD IMPEDANCE AND DEVICE FAILURE, [IT WAS] OBSERVED OTHER FACTORS RESULTING IN LEAD FAILURE.¿ ¿VNS LEAD FAILURE MOST COMMONLY RESULTED IN AN INCREASED SEIZURE FREQUENCY. IN SOME CASES, A VERY DRAMATIC INCREASE IN SEIZURE INTENSITY AND FREQUENCY WAS OBSERVED. HOWEVER, OTHER SYMPTOMS ALERTED PATIENTS TO DEVICE MALFUNCTION AND INCLUDED NECK AND CHEST PAIN, SHOCK-LIKE SENSATIONS, AND PARESTHESIAS. SHORT CIRCUITS WITHIN THE SYSTEM MAY CAUSE THESE TYPES OF SYMPTOMS.¿ THE SHOCK-LIKE SENSATIONS, PAIN, AND PARESTHESIAS RESOLVED AFTER REVISION. THE ARTICLE ALSO NOTED THAT ¿OTHER CONFOUNDING VARIABLES INCLUDE THE CHANGING ANTIEPILEPSY DRUGS PATIENTS POTENTIALLY RECEIVED OVER THE FOLLOW-UP PERIOD. FURTHERMORE, THE CLINICAL ABSENCE OF DYSPHONIA OR ASPIRATION DOES NOT PRECLUDE THE POSSIBILITY OF VAGUS NERVE INJURY, AND THEREFORE UNDERREPORTING OF ACTUAL INJURY MAY BE PRESENT.¿ ATTEMPTS FOR ADDITIONAL INFORMATION, INCLUDING PATIENT INFORMATION, HAVE BEEN UNSUCCESSFUL TO DATE. THIS REPORT CAPTURES A PATIENT'S LEAD REVISION AS A RESULT OF INCREASED SEIZURES AND NECK/CHEST PAIN. THE PATIENT'S INFECTION IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01454. THE EVENTS OF HIGH IMPEDANCE ACCOMPANIED WITH INCREASED SEIZURES ARE CAPTURED IN MFG REPORT NUMBERS: 1644487-2013-01426, 1644487-2013-01428, 1644487-2013-01431, 1644487-2013-01432, 1644487-2013-01434, 1644487-2013-01435, 1644487-2013-01436, 1644487-2013-01443, 1644487-2013-01445, 1644487-2013-01448, AND 1644487-2013-01451. THE EVENTS OF LEAD FRACTURE ACCOMPANIED WITH INCREASED SEIZURES ARE CAPTURED IN MFG REPORT NUMBERS: 1644487-2013-01427 AND 1644487-2013-01438. THE EVENTS OF HIGH IMPEDANCE WITH NO REPORTED PATIENT ADVERSE EVENTS ARE CAPTURED IN MFG REPORT NUMBERS: 1644487-2013-01429, 1644487-2013-01430, 1644487-2013-01441, AND 1644487-2013-01456. THE EVENT OF HIGH IMPEDANCE DUE TO ELECTRODE DETACHED/DISLOCATED FROM THE VAGUS NERVE IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01440. THE EVENT OF HIGH IMPEDANCE ACCOMPANIED WITH INCREASED SEIZURES AND SHOCK SENSATION IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01433. THE EVENT OF POSTOPERATIVE ¿BOWSTRING COMPLICATION REQUIRING SURGERY 1 MONTH LATER¿ IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01465. THE EVENT OF LEAD FRACTURE (WITH NORMAL LEAD IMPEDANCE VALUE) WITH NO REPORTED PATIENT ADVERSE EVENTS IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01458. THE EVENTS OF SHORT CIRCUIT ACCOMPANIED WITH INCREASED SEIZURES ARE CAPTURED IN MFG REPORT NUMBERS: 1644487-2013-01442 AND 1644487-2013-01455. THE OTHER EVENTS OF INFECTION ARE CAPTURED IN MFG REPORT NUMBERS: 1644487-2013-01437 AND 1644487-2013-01457. THE EVENT OF INCREASED SEIZURES WITH SHOCK SENSATION IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01446. THE EVENT OF AN UNKNOWN OF AMOUNT OF PATIENTS WITH INCREASE IN SEIZURE INTENSITY IS CAPTURED IN MFG REPORT NUMBER: 1644487-2013-01466.