Abstract
Cardiovascular changes following lumbar spine surgery in a prone position are exceedingly
rare. Over the past 20 years, a total of six cases have been published where patients
experienced varying degrees of bradycardia, hypotension, and asystole, which could
be attributed to intraoperative dural manipulation. As such, there is emerging evidence
for a potential neural-mediated spinal-cardiac reflex. The authors report their experience
of negative chronotropy during an elective lumbar spine surgery that coincided with
dural manipulation and review the available literature. A 34-year-old male presented
with a long-standing history of lower back pain recently deteriorating to bilaterally
radiating leg pain, with restricted left leg raise, and numbness at the left L5 dermatomal
territory. The patient was an athletic police officer with no comorbidities or past
medical history. Magnetic resonance imaging lumbosacral spine revealed spinal stenosis
most pronounced at L4/L5 and disc bulges at L3/L4 and L5/S1. The patient opted for
lumbar decompression surgery. After an unremarkable comprehensive preoperative workup,
including cardiac evaluation (electrocardiogram, echocardiogram), the patient was
induced general anesthesia in a prone position. A lumbar incision was made from L2
to S1. When the left L4 nerve root was retracted while removing the prolapsed disc
at L4/L5, the anesthetist cautioned the surgeon of bradycardia (34 beats per minute
[bpm]), and the surgery was immediately stopped. The heart rate improved to 60 bpm
within 30 seconds. When the root was later retracted again, a second episode of bradycardia
occurred for 4 minutes with heart rate declining to 48 bpm. The surgery was stopped,
and after 4 minutes, the anesthetist administered 600 µg of atropine. The heart rate
then rose to 73 bpm within 1 minute. Other potential causes for bradycardia were excluded.
The total blood loss was estimated to be 100 mL. He remains well at his 6-month follow-up
and has returned to work as normal. Akin to previously published cases, each episode
of bradycardia coincided with dural manipulation, which may indicate a possible reflex
between the spinal dura mater and the cardiovascular system. Such a rare adverse event
may occur even in seemingly healthy, young individuals, and anesthetists should caution
the operating surgeon of bradycardias to exclude operative manipulation of the dura
as the cause. While this phenomenon is only reported in a handful of lumbar spine
surgery cases, it provides evidence for a potential spinal-cardiac physiological reflex
in the lumbar spine that may be neural mediated and should be investigated further.
Keywords
bradycardia - negative chronotropy - lumbar spine - mechanism - spinal-cardiac reflex
