Fig 2. The surgical scope included the supraorbital hole and painful
parts of the forehead and the top of the head. After local anesthesia
with 1% lidocaine, the puncture needle was inserted into the skin.
Every 0.5cm was an ablation point, and the ablation time at each point
is electric cutting for 5S and electric coagulation for 5S.
After the initial operation, the interval between the onset of pain was
prolonged to 3-4 hours, the duration was reduced to 1.5-2 minutes, and
the forehead pain disappeared at the onset; After the second operation,
the interval of pain attack was further extended to 5-6 hours, the
duration was still 1.5-2 minutes, and the pain range was reduced to
about 4.5 * 5cm at the top.The trigeminal ganglion lateral approach was
blocked once on the second and third day after operation. During the
treatment, the patient took the supine position and turned his head to
the healthy side. The lateral approach of trigeminal nerve semilunar
ganglion through temporomandibular point was used. Disinfect the skin,
spread sterile towel, and ask the patient to open the mouth slightly.
The puncture point was the upper edge of the mandibular notch about 1cm
from the midpoint of the lower edge of the temporal arch to the tail.
For local anesthesia with 1% lidocaine, uses a 5ml syringe needle from
the puncture point close to the upper edge of the mandibular notch to
pierce in the direction of 15 ° - 20 ° backward and 15 ° - 30 ° upward.
The needle can reach about 4.5cm, and radiation pain can occur near the
foramen ovale. Then withdraw the needle slightly and inject drugs
(ketochromate aminobutanol, ribavirin injection, 2% lidocaine,0.9%
normal saline mixture) 2ml. On the morning of the fourth day after
operation, the patient complained that the pain of the previous night
had not occurred, and the ocular photophobia symptoms were significantly
improved. There was no recurrence of pain after 3 days in hospital, VAS
score: 0. After 30 days of follow-up, no pain occurred, VAS score: 0,
SF-36 score: physiological function (PF): 70, physiological function
(RF): 100, Body pain (BP): 72, general health status (GH): 67, energy
(VT): 70, social function (SF): 100, emotional function (RE): 100,
mental health (MH): 76, health change (HT): 50; Pittsburgh sleep quality
index: 7.
3 | Discussion
Trigeminal nerve is the main sensory nerve in the face. After the
initial infection of herpes zoster, the virus is latent in the
trigeminal ganglion. With the decline of human immunity, the latent
herpes zoster virus can be reactivated and replicated, and the
peripheral nerves associated with the infected ganglion will have
lesions[8]. Severe inflammatory reactions can
occur in the invaded ganglia, manifested as neuronal edema, necrosis and
intraneural hemorrhage, resulting in neuropathic pain[9].In addition, the peripheral sensitization
mechanism is also considered to be one of the possible causes of PHN,
which is mainly manifested in the ectopic discharge of damaged
peripheral afferent fibers. Studies[10] have shown
that demyelinating changes and abnormal regeneration can occur after
peripheral nerve injury, resulting in the formation of neuroma. Under
the condition of no stimulation, neuroma can discharge spontaneously,
while under chemical or mechanical stimulation, it will increase the
discharge frequency of neuroma and cause severe pain. In the course of
PHN, abnormal sprouting of small peripheral nerve fibers is similar to
the external ectopic discharge in neuroma, which will cause abnormal
feelings such as local skin pain and itching. Studies have shown that
local anesthetics or proximal nerve block infiltrating painful skin can
temporarily inhibit ongoing pain [11-13].This
shows that part of the pain caused by PHN comes from the pathological
changes of peripheral fibers. At the same time, inhibiting the activity
of skin ectopic discharge (pacemaker) can effectively alleviate the
pain. In addition to the above theory of pain caused by nerve injury,
some scholars believe that herpes zoster virus (VZV) still exists in the
body at PHN stage and may cause pain symptoms.
Low temperature plasma ablation is a kind of minimally invasive
interventional therapy. It is a new technology based on electrochemistry
developed in recent years. It uses bipolar RF to generate energy to
convert the electrolyte between the tissue and the RF cutter head into a
plasma thin layer. The charged particles in the plasma are accelerated
by the electric field to transfer energy to the tissue, dissociate the
molecular bonds constituting cell components in the target tissue, and
decompose the tissue into small molecular gases to achieve the purpose
of tissue volume reduction. At present, low-temperature plasma
technology is mostly used in the treatment of cervical and lumbar
discogenic diseases. It is the first in our department to apply it to
the treatment of neuropathic pain after herpes zoster.
Since 2016, more than 30 patients with intractable herpes zoster
neuralgia have been treated. Statistics show that the effective rate is
86.67%, and the excellent rate is 76.67%. The main theoretical basis
is: the temperature of the low-temperature plasma knife head is
maintained at 40-70 ℃ [14], while the nerve fibers
conducting pain will denature only after 120 seconds above 70 ℃.
Therefore, this treatment will not cause the denaturation of normal
nerve tissue, but it is possible to inactivate the abnormally sprouted
unmyelinated terminal fibers, so as to correct the discharge and
activity of ectopic pacing points of the skin, improving the internal
environment of peripheral nerve, and finally achieve continuous
remission of symptoms for a long time.Secondly, when the plasma cutter
head works, it can instantly produce a large amount of exogenous
reactive oxygen species (ROS) and reactive nitrogen (RNs). Some studies
have shown that ROS and RNS play an important role in the potential
biological effects of plasma [15–17]. ROS is
involved in the transmission of cellular signals and is related to many
biological systems [18]. It recruits many
different mitogen activated protein kinases (MAPKs), resulting in the
activation of cellular signal cascade [19]. This
is likely to be involved in the mechanism of PHN pain regulation. In
addition a large number of literatures have confirmed that
low-temperature plasma has inactivation effect on microorganisms such as
bacteria and viruses.Some theories believe that the occurrence of PHN
may be related to VZV remaining in nerve tissue, so the treatment of PHN
with low-temperature plasma technology can not only target the
pathological changes of nerve tissue itself, but also inactivate the
pathogenic microorganism VZV virus, which not only alleviates the
existing pain of patients, but also fundamentally eliminates the
possibility of recurrence or aggravation of pain.
After receiving low-temperature plasma nerve conditioning, the pain in
some areas of the top was still not relieved. Combined with the current
understanding of the mechanism of PHN, it is considered that the
trigeminal ganglion may have inflammatory and hemorrhagic changes due to
VZV. Therefore, puncture and injection through the lateral approach of
trigeminal ganglion and local infiltration of antiviral,
anti-inflammatory and local anesthetic drugs were used in order to
alleviate the inflammatory lesions of trigeminal ganglion and give
targeted treatment to the possible VZV virus.The response after
treatment was indeed as we expected, and the patient’s symptoms
disappeared. In this case, the first branch of the trigeminal nerve was
involved. In addition to the pain symptoms, there were corneal
involvement symptoms at the same time. After receiving low-temperature
plasma nerve conditioning, not only the pain range, attack frequency and
attack duration were significantly improved, but also the ocular
symptoms were significantly relieved. There was no obvious abnormal
sensation at the treatment site, and there were no other adverse
sequelae. It can be seen that this method can not only treat the pain
symptoms caused by PHN, but also protect the eye function for patients
with the first branch of trigeminal nerve involved.