Trigeminal neuralgia (TN) may sometimes present secondary to an
intracranial cause. Arnold Chiari Malformation (ACM) is downward
herniation of the cerebellar tonsils through the foramen magnum
that may be a cause of TN-like pain in very rare cases.
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The aim of this brief report is to suggest the proper management of
uncommon secondary trigeminal neuralgia related to a rare Arnold
Chiari type I malformation.
A male patient presented electric shock-like stabbing pain on the
right side of the face for more than ten years. The symptoms were
typical of trigeminal neuralgia except that there was the loss of
corneal reflex on the right side and the patient also complained of
gait & sleep disturbances. A complex and multilevel diagnosis was
Multiplanar imaging through brain acquiring T1/T2W1 revealed ACM
Type I Malformation with a caudal displacement of cerebellar
tonsils through the foramen magnum.
Dental surgeons and oral and Maxillofacial Surgeons should exclude
intra-cranial causes by Magnetic Resonance Imaging (MRI) in
patients of TN presenting with loss of corneal reflex, gait, and
sleep disturbances due to nighttime pain episodes. The severe
trigeminal neuralgia could be related to ACM also thanks to the
unusual finding of the loss of corneal reflex. What are the
implications for research, policy, or practice? This case
highlighted how a correct diagnosis must first exclude the severe
intracranial pathology in the case of TN.
Trigeminal neuralgia (TN) is a chronic condition characterized by
pain presenting in brief episodes, in one or more distributions of
the trigeminal nerve. Episodes of pain secondary to TN are
triggered by specific or not specific stimuli, such as chewing,
shaving, or touching the face. A common cause of TN is compression
of the trigeminal nerve root entry zone by an artery or vein, many
cases of TN are idiopathic.
Trigeminal neuralgia (TN) a sudden, usually unilateral, severe,
brief, stabbing, recurrent pain in the distribution of one or more
branches of the fifth cranial nerve is one of the most painful
conditions on the face and has a profound impact on the quality of
life as this prevents the patient from speaking, eating, drinking,
touching or washing of the face and brushing teeth.
TN patients often initially present to dental surgeons who
subsequently refer them to Oral & Maxillofacial Surgeons. Patients
with TN are at times misdiagnosed and undergo misguided,
unnecessary procedures and ineffective treatments. Some clinicians
consider the diagnosis of TN to be purely history and clinical
examination based without the need for any further investigation.
In the majority of cases TN may be primary (idiopathic) but rarely
may arise secondary to an intracranial cause.
Typically, TN is diagnosed by the patient’s clinical history,
supported by a negative neurologic exam, and after a positive
response to a trial of carbamazepine. NMR studies are often useful,
especially when the diagnosis is uncertain or neurologic disorders
are present. Many conditions are triggered by the compression of
the Trigeminal nerve, even if the compression is within a few
millimeters before entry into the pons.
Neuroimaging may help in differentiating between primary and
secondary TN by identifying an intracranial cause in up to 15 percent
of patients and thus help correct diagnosis and management. TN may
rarely be associated with Arnold Chiari 1 malformation (ACM). ACM
is a group of complex brain abnormalities traditionally defined as
downward herniation of the cerebellar tonsils through the foramen
magnum. Diagnosis of ACM with MRI evaluation of posterior cranial
fossa is confirmed if the cerebral tips have exceeded 5mm below the
foramen magnum. It occurs in about 0.4:1000 live births and has
formed 3 percent of all abortions.
A 65-years-old male presented electric shock-like stabbing pain on
the right side of the face for more than ten years. He was unable
to eat, drink, speak or sleep properly because of the severity and
multiple episodes of pain during the day and even at night during
sleep. He was taking carbamazepine 200mg and gabapentin 300mg twice
daily without much relief in pain. On clinical examination, there
was a loss of corneal reflex on the right side and the patient also
complained of gait disturbances. On intraoral examination, he had
lost most of his teeth because of his inability to maintain proper
oral hygiene due to the triggering of pain while brushing. He lost
some of his teeth due to the TN pain mimicking a toothache
during the early stages of his disease as shown in his panoramic
radiograph. Based on history and clinical examination, secondary TN
was suspected, and an MRI brain scan was advised to identify the
probable intracranial cause for the pain. Multiplanar imaging
through brain acquiring T1/T2W1 revealed caudal displacement of
cerebellar tonsils through the foramen magnum. There was
compression of the cervical-medullary junction with a syrinx in the
cervical cord suggesting Arnold Chiari malformation type I. The
patient was subsequently referred to the neurosurgery department
for decompression (occipital craniotomy and laminectomy).
Chiari malformations (CM) was named after Hans Chiari, an Austrian
pathologist, who first identified this pathology in 1891. After that
Julius Arnold further elaborated on malformation which became now to be
known as Arnold-Chiari malformation (ACM). ACM is classified into
four types. Specifically, type 1 is characterized by herniation of
cerebellar tonsils alone, radiologically as simple tonsillar
herniation 5mm or greater, below the foramen magnum. Presentation
of TN secondary to ACM is extremely rare as a very small number of
such cases have been reported in scientific literature. In this
specific clinical report, we first describe a TN secondary to ACM
in the whole country of Pakistan. The pathophysiology of TN secondary
to ACM is hypothesized to be due to a variety of problems that may
include vascular compression at the nerve root entry zone (NREZ) of the fifth cranial nerve, demyelination of the trigeminal NREZ,
micro-ischemic changes, and direct brainstem compression. In ACM
spinal tract of the trigeminal nucleus is more susceptible as it is
located dorsally and is poorly myelinated. A variety of treatment
options are available for TN secondary to ACM that may include
microvascular decompression (MVD), retro-sigmoid craniotomy,
endoscopic third ventriculostomy, and ventricular shunt procedures.
Craniocervical decompression has been reported with a 73 percent
resolution of pain symptoms. It could be interesting to approach
future therapies by using mesenchymal stem cells, given their
paracrine immunoregulatory effects.19 Several risk factors should
be also avoided in TN, as some factors could be involved in the
processes of cytopathic hypoxia and of cellular oxidative stress.
Finally, the diagnosis must even consider and exclude, oncological
issues, and syndromic conditions especially those related to oral
and maxillofacial regions, or micro-and macro-trauma, eventually
treated with traditional or innovative autologous scaffolds.
Chiari I malformation usually presents with headache, numbness,
weakness, and gait abnormalities. This case report is an addition to
the very few reported cases of TN secondary to ACM. Dental surgeons
and oral & Maxillofacial Surgeons should consider this diagnosis in
patients of TN presenting with loss of corneal reflex, gait, and
sleep disturbances due to nighttime pain episodes; and
unsuitable treatment interventions. This report supports early
surgical intervention for symptomatic patients to achieve long-term
pathophysiology of TN in these cases may be due to neurovascular
conflict. MRI in all patients presenting with TN is mandatory,
which may provide valuable etiological information, prevent the
progression of the disease, and avoid erroneous diagnosis surgical
benefits. The Patient lost some of his teeth due to the TN pain
mimicking a toothache during the early stages of his disease as
shown in his panoramic radiograph. Most TN patients lose some or
all of their teeth before getting diagnosed. Figure- MRI Brain
showing caudal displacement of cerebellar tonsils through foramen
magnum Dr. Mike’s point, “This can be managed with Burcon
cervical specific chiropractic care. Why resort to drugs and
surgery when specific adjustments work just as well?
This patient got rid of her Meniere’s symptoms for five months with
surgery. Then they came back until I adjusted her with the approval
of her MD. That adjustment also held for five months,” Dr.
Michael T. Burcon, B.Ph, D.C.