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1.8.2. Deaths
A total of 524 deaths were reported to the FDA during the period from July
1, 1997 through October 8, 2004. By the end of the period, there were
32,065 VNS Therapy device implants and 80,144 device-years of implant
experience. Of the 524 deaths, 102 (20%) were of an “unknown cause,”
including 24 deaths of unknown cause that occurred during sleep (5% of
total deaths). Of those deaths with a reported cause, the following were the
most common etiologies:
�� Seizure disorder (152 reports; 29% of total deaths), including sudden
unexplained death in epilepsy and status epilepticus
�� Respiratory events (99 reports; 19% of total deaths), including
pneumonia, pulmonary edema, and hypoxia
�� Cardiac events (51 reports; 10% of total deaths), including
cardiopulmonary arrest, infarction, and arrhythmias
�� Neurovascular events (24 reports; 5% of total deaths), including stroke
and cerebral hemorrhage
�� Malignancy (19 reports; 3% of total deaths), including brain and colon
�� Suicide (9 reports; 2% of total deaths)

1.8.3. Serious Injuries
A total of 1,644 serious injuries were reported to the FDA during the
period from July 1, 1997 through October 8, 2004. By the end of the
period, there were 32,065 VNS Therapy device implants and 80,144
device-years of implant experience. The most frequently reported serious
injury was infection (525 reports). Approximately 40% of these were
known to have required device explantation. The second most common
serious injury reported was increased seizure activity (324 reports). Others
included:
�� Vagus nerve injury (181 reports), including vocal cord paralysis (109)
and hoarseness (71)
�� Respiratory injuries (141 reports), including sleep apnea (33), dyspnea
(50), and aspiration (14)
�� Cardiac events (123 reports), including tachycardia, bradycardia,
palpitations, hypertension, hypotension, syncope, and asystole
�� Pain (81 reports), including chest and neck pain
�� Gastrointestinal events (60 reports), including dysphagia (24) and
weight loss (24)
�� Depression (21 reports)
Of the 1,644 reports of serious injury, 694 (42%) were associated with
subsequent device explantation in that subject.

1.8.4. Device Malfunctions
A total of 708 device malfunctions were reported to the FDA during the
period from July 1, 1997 through October 8, 2004. By the end of the
period, there were 32,065 VNS Therapy device implants and 80,144
device-years of implant experience. Some of the most common
malfunctions reported were high lead impedance (351), lead breakage
(116), device failure (44), and device migration (20).


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