trigeminal neuralgia ( tn ) , a neuropathic pain syndrome , is defined by the international association for the study of pain as " a sudden and usually unilateral severe brief stabbing recurrent pain in the distribution of one or more branches of the fifth cranial nerve"3 ) .
vascular compression and resultant injury to the trigeminal nerve at its root entry zone ( rez ) are the proposed mechanisms of tn5 ) .
the vessel that most often causes tn is the superior cerebellar artery ( sca ) , other known offending vessels include the anterior inferior cerebellar artery ( aica ) and the vertebrobasilar trunk and vein .
case reports have also rarely described tn caused by a primitive trigeminal artery ( pta)2,4,8,9 ) .
we introduce a case of tn caused by pta that was successfully treated with surgery .
a 66-year - old male presented to our hospital with a 9-year history of typical left trigeminal neuralgia symptoms that gradually became refractory to medical treatment . magnetic resonance angiography ( mra ) revealed a pta arising from the postero - lateral aspect of the posterior genu of the cavernous segment of the left internal carotid artery .
the pta coursed postero - laterally and inferiorly around the dorsum sellae . in its lateral course
1 ) . a three - dimensional time - of - flight mra showed a pta coursing around the trigeminal nerve ( fig .
then , with adequate drainage of cerebrospinal fluid and gentle retraction of the cerebellum , we observed the trigeminal nerve and vessel , which were compressed into the caudomedial part of the nerve . in the operational field , we confirmed that the vessel came into contact with the trigeminal nerve with a loop in the posterolateral direction ( fig .
we transposed the pta laterally away from the nerve , and decompressed the nerve by interposing teflon between the vessel and the nerve .
postoperatively , the patient 's pain disappeared completely without sequelae . after receiving medication for 1 year , the patient remained pain - free without medication thereafter .
a persistent pta is an uncommon vessel with a reported incidence of 0.03 - 2.2% in the literature10 ) . cases of pta - induced tn are even rarer . during embryonic intracranial vascular development ,
the trigeminal artery is the largest of the fetal carotid - basilar anastomotic arteries , and it persists for the longest embryonic period6,7 ) .
the exact causes of the persistence of this primitive vessel into adulthood are not completely clear1 ) .
the pta of adulthood courses through the cavernous sinus and emanates from the posterior wall of the cavernous sinus , following either a para- or intrasellar course1,6,7 ) .
the pta reaches the posterior cranial fossa in two ways : by 1 ) penetrating the sella turcica , running in its own groove , and perforating the dura mater near the clivus in about half of cases ; or by 2 ) running extradurally after leaving the cavernous sinus and traveling between the sensory trigeminal root and the lateral side of the sella in a groove of the posterior clinoid process in the other half . in our case , we visualized the pta coursing postero - laterally and inferiorly around the dorsum sellae .
furthermore , we were able to identify the cause of the patient 's tn by the pta 's proximity to the trigeminal nerve .
several reported cases of pta - induced tn utilized cerebral angiography for verification of the pta4,8,9 ) . in our case , we intended to implement cerebral angiography for pta identification ; however , we used mra only
. mra can fully confirm the vessel that induces tn , so patients who need surgical treatment may undergo an operation without being exposed to the risks of cerebral angiography .
cerebral angiography has the advantage of accurately displaying the vessels , but it can not show the relationship of the vessels to the nerve structures .
preoperative visualization of the specific vessel causing tn is important in patients who require surgery .
when the patient 's condition is unable to tolerate cerebral angiography or when the patient is refusing further invasive evaluation , preoperative mra or computed tomography angiography ( cta ) may confirm the vessel .
in addition , proper visualization may reveal the orientation of the vessel around the nerve , aiding in surgical planning . in the present case , we used mra to verify the causal vessel . furthermore , we evaluated the vessel and its surrounding structures using cta and evaluated the relationship between dural structures and the nerve on mra .
the combination of mra and cta was useful for understanding the anatomy of the surgical field .
as shown in our case , the usefulness of mra and cta has been confirmed by the similarity of mra images and operative findings . in this way
, we were able to properly plan and execute surgical treatment while avoiding invasive cerebral angiography .
preoperative mra imaging sufficiently confirmed the vessel that induced tn , leading to a successful operation .
 a 66-year - old man presented with typical trigeminal neuralgia ( tn ) . 
 magnetic resonance angiography ( mra ) revealed a primitive trigeminal artery ( pta ) that came into contact with the trigeminal nerve . 
 based on mra , we performed microvascular decompression ( mvd ) . in the operational field , we confirmed the pta location and performed mvd successfully . 
 postoperatively , the patient 's pain subsided without any complications . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION