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Helen Triantafyllidi, MD, PhD
Hypertension Specialist
Chief of Hypertension Unit
2nd Department of Cardiology, Medical School,
University of Athens, ΑΤΤΙΚΟΝ Hospital
Intervational therapies for hypertension:
Bilateral sphenopalatine ganglion blockade
There is no conflict of interest
54% of strokes and 47% of IHDattributable to hypertension
Comment: This surgical intervention
was highly effective in reducing BP and
mortality, however, at the cost of very
severe complications in particular
orthostatic hypotension and a high
morbidity and mortality (1935-1960).
In terms of Efficacy: Better BP reduction with RDN
than sham-control group by all measures, HOWEVER
▪ not better than changes expected from a single
added antihypertensive pill
▪ considerable variability
▪ long-term efficacy is lacking
▪ possibility of nerve regrowth still exists
In terms of Safety: Results of recent sham-control studies indicate that RDN is
safe, HOWEVER
▪ renal artery stenosis has been reported post-RDN
▪ atherosclerotic lesions after endothelial injury can progress slowly and may
take years to become clinically apparent.
The sphenopalatine ganglion (SPG) is the largest
collection of neurons in the head outside of the brain,
located in the pterygopalatine fossa, posterior to the
middle nasal turbinate, under a 1–1.5 mm layer of
connective tissue and mucus membrane.
It has rich autonomic sympathetic and
parasympathetic components from the superior cervical
ganglion and it is connected with the brain stem and the
central nervous system (CNS).
SPG block by lidocaine is currently indicated in the
management of 1. medically resistant cluster headaches,
2. migraine, 3. trigeminal autonomic neuralgias as well
as 4. intractable orofacial pain syndromes.
The analgesic effect typically lasts beyond the
duration of anesthesia caused by the nerve blockade,
providing some patients with pain relief for several
weeks or even months. This prolonged analgesia may be
due to an effect on central pain modulation.
Sphenopalatine ganglion
G. Sluder. The role of the sphenopalatine
ganglion in nasal headache, N. Y. State J.
Med. 27 (1908) 8–13.
Responders: 24h SBP reduced by >5 mmHg
n=11/22 (50%)
Controls under sham
procedure with water for
injection instead of
lidocaine
Responders: 24h SBP reduced by >5 mmHg
n=12/33 (33%)
Responders:
24h SBP reduced by 9 mmHg
24h DBP reduced by 6.5 mmHg
➢Who responds: Responders presented with higher SBP at baseline (24 h,
daytime and night-time) compared with the non responders.
➢Safety: We did not notice any acute PR interval, BP or heart rate (HR)
alterations. Subsequently, it seems that there is no direct interaction between SPG
block and the cardiovascular SNS, instead a gradual decrease of BP levels for
the next 20–30 days after the SPG block was noticed.
➢Minor side-effects: Total destruction of the SPG by radiofrequency treatment
might lead to dryness of the eye (unusual), an “open nose” because the mucosa has
less inclination to swell, and hypesthesia or dysesthesia of the soft palate, maxilla,
or posterior pharynx. Numbness of the soft palate is usually temporary, and
sometimes loss of taste can be permanent. Subsequently, applying a long-term
deletion of the SPG block in antihypertensive treatment instead of SPG anesthesia
might affect the quality of life in a hypertensive population.
➢However, using lidocaine none of our patients suffered such a complication.
Sphenopalatine ganglion
block
• Our results indicate that SPG block might be a promising, non-invasive, safe,
painless and easy to perform therapeutic option of BP decrease without any
subsequent complications.
• It resembles to renal denervation as to the need of a bilateral application and the
unknown immediate effect since no drop in blood pressure is seen just after the procedure.
However, as SPG block just causes an anesthetic effect instead of destroying the nerve
fibers, a lot of questions emerge as for the long term BP decrease and when the
procedure has to be repeated as well as which is its impact in patients with more
severe arterial hypertension or even resistant hypertension.
• Finally, as with renal denervation, SPG should be effective in those hypertensive
patients with an activated SNS, so a period of patient selection should precede the
application of this procedure. On the other hand, SPG block might work as a selection
test for RDN procedure. We believe that the responders to SPG block hypertensive
patients might be the true responders to SNS modulation that RDN procedure seeks with a
subsequent long-standing BP decrease.
Sphenopalatine ganglion
block
Consequently, brain is connected with SPG through pretectum (midbrain),
ciliospinal center (spinal cord), SCG (cervical sympathetic trunk), internal carotid
artery and deep petrosal nerve (PPF).
Neural routesThe preganglionic sympathetic neurons
1. start from the ciliospinal center, a
structure which receives input from
the pretectum (midbrain structure)
and is located at the intermediate
horn of grey matter of the spinal cord
between the C8 and T1 regions, then
2. they ascend the cervical sympathetic
trunk to the superior cervical
ganglion (SCG) to synapse with the
postganglionic neurons (SCG input).
3. The postganglionic fibers follow
along the internal carotid artery
and enter the skull and the PPF as the
deep petrosal nerve which passes
through the SPG.
Sympathetic fibers under anesthesia (SPG) should transmit fewer neural
signals to the superior cervical ganglion:
1. Suppressed superior cervical ganglion sends fewer signals directly to CNS
resulting to BP decrease.
2. It seems likely that sympathetic excitation induces a sympathetic reflex causing
internal carotid and vertebrobasilar insufficiency and eventually resulting to
hypertensive response while the sympathetic withdrawal should lead to increased
blood flow and subsequent BP levels decrease.
3. The superior cervical ganglion and the carotid sinus of the internal carotid
artery are connected directly. It is suggested that the superior cervical ganglion
controls, at least partially, the state of contraction of the carotid sinus arterial wall and
thus has a role in the reflex homeostasis of blood pressure (fewer signals to carotid
sinus). On the other hand, increased blood flow due to sympathetic withdrawal after
SPG block should trigger a hypotensive response through carotid sinus pressure
receptors.
Proposed mechanisms of action
and BP lowering
✓ Impaired patient's compliance is one of the main reasons of the failure of any
antihypertensive medical treatment. Invasive methods should improve patient's
compliance to treatment due to the decreased number of antihypertensive
drugs needed.
✓ Renal artery nerves mapping, renal denervation, arterio-venous iliac fistula,
carotid barostimulation offer a new insight in arterial hypertension. Subsequently,
invasive methods of arterial hypertension management work but it is not known
yet who is the perfect candidate for their success.
✓ We feel that SPG block, a non-invasive method, might work either as a
therapeutic option after repeated blocks or as a selection test for RDN
procedure since responders to SPG block might be the right candidates for RDN
procedure.
✓ We will continue our research project in groups of ESRD patients as well as in
hypertensive patients with resistant hypertension while we are going to try a new
catheter for SPG blockade, the Tx 360.
Take home messages