OBLITERATING FORAMINA FOLLOWING PERIPHERAL NEURECTOMIES CAN PROLONG
REMISSION OF NEURALGIA UP TO 10 YEARS
pain over the area previously innervated by the
incisive nerve. Injections of plain bupivacaine 0.5%
were able to provide temporary pain relief. The
dosage of carbamazepine was increased to 200
mg t.d.s and this was able to control the neuralgia.
Beside the right infraorbital and incisive nerves,
the right long buccal and greater palatine
nerves were also experiencing neuralgia, with a
neurectomy done to the greater palatine nerve
in 1999 and subsequent repeat neurectomy and
the insertion of a 2.0 mm titanium screw under
general anesthesia in 2001. The pain over the right
long buccal nerve region was relieved when an
endodontist performed a root canal treatment on
the lower right second molar.
To conclude, the obliteration of the infraorbital
and incisive foramens managed to provide
adequate pain control that lasted up to 10 years.
The obturation of the greater palatine foramen
provided pain relief for almost 14 years. She has
since developed trigeminal neuralgia over the
right lateral nasal region and the right mental
nerve. Root canal therapy on the lower right first
premolar did not manage to provide pain relief on
this occasion. A 2.0 mm titanium screw was inserted
to the right mental foramen after neurectomy in
2004 (Fig. 1). She eventually underwent gamma
knife surgery to control the neuralgia in 2006 and
was lost to follow ups.
Discussion
Early literature revealed that there have always
been two major means of treatment for trigeminal
neuralgia; medical and surgical.23 The difference
with current treatment is that medical treatment
in the past included topical applications of
lotions, vesicants, heat, opiates, counterirritants
such as plasters and blisterings, and leeches,
bleeding, and purging23, and the inhalation
of trichloroethylene.26 In the early nineteenth
century, the drugs of choice included quinine
sulfate, ferrous carbonate, hemlock, camphorated
mercurial ointment, ether and arsenic in gruel.
By the turn of the century, vitamin B and liver
extracts, vasodilators, intravenous histamines,
chlorpromazine, mephenesin carbamate, and
cobra venom were added to the list.23 This shows
how little we understood trigeminal neuralgia until
the introduction of dilantin and carbamazepine.
Carbamazepine, unfortunately, is not a miracle
drug that is effective in all patients, and its effect
may not be long lasting. One study assessed
the long-term efficacy of carbamazepine over a
16-year period in 146 patients and reported an
initial success in 60% of participants, but by 5 – 16
years only 22% of participants were still finding
carbamazepine effective and 44% required
additional or alternative treatment. 5 This scenario is
exactly what happened to the patient in this current
case. She underwent various peripheral surgical
approaches to treating trigeminal neuralgia
which included alcohol injection, cryotherapy and
peripheral nerve avulsion (neurectomy), since she
failed to fully respond to carbamazepine. Alcohol
injection of the branches of the trigeminal nerve
has been carried out since early 20th century27,
28
Schlosser has been cited as the first person
to advocate the use of alcohol injection29 There
are two distinct techniques to deliver peripheral
injection of alcohol. In one of the techniques, a
transcutaneous injection of the nerve at the skull
base at the foramen ovale or foramen rotundum is
performed. A second technique delivered alcohol
more distally as the nerve passes recognizable
foramina in the facial skeleton. Injection of alcohol
(1 mL of 100% absolute alcohol), while can be
easily performed, is done blindly. It is difficult to
control the spread of the agent injected into the
closed space.
This approach has been reported to relieve pain
for an average time interval of 11-17 months7, 30,
but with a 10-39% failure rate12, 30, 31-33 However,
there will be a fall in the duration of effect with
subsequent injections26, 34 and rightly enough,
such a situation was seen in the current case. Even
though alcohol injections had been employed
near the foramen, it did not cause permanent nerve
destruction. In fact, the nerve kept regenerating,
resulting in her needing re-injections every 2-3
months.
Cryotherapy, first introduced in 197635, has been
administered with some success in this case.
Cryotherapy for trigeminal neuralgia can only be
applied to exposed nerve branches and not the
whole divisions as is done with neurectomy. Thus,
the patients’ sign and symptom recurred soon
after cryotherapy. Cryotherapy can provide relief
of painful symptoms for about one year, as seen
in this case. This is not much different from the
median time to pain recurrence reported for the
infraorbital (14 months), mental (9 months) and
long buccal (11 months) nerves.36 This also means
that the patient still needed repeat cryotherapy.
The only advantage of cryotherapy over alcohol
injection and peripheral neurectomy is that there
is no permanent sensory loss.
Peripheral neurectomy is not a new surgical
procedure, first introduced as a treatment modality
in the 18th century.9, 12 The first comprehensive
review was published by Fowler in 188611, and
following the turn of the century, it was among the
three means of treatment for trigeminal neuralgia,
along with alcohol injection and ganglion root
resection.37 It is claimed to be a simple, lowrisk, repeatable surgery that can be performed
under local anaesthesia, as shown in this case.
Post Second World War, the earliest studies were
published about 50-60 years ago9, 12, 15-17, 21-23, 30, 38,
followed by sporadic publications on this mode of
treatment thereafter.18,24,39
Cherrick23 in presenting a case report of bilateral
trigeminal neuralgia in 1972 stated that peripheral
neurectomy was a very popular and successful
treatment then, with very few postoperati