Duplication of Right Superior Cerebellar Artery Leading to Trigeminal Neuralgia: A Rare Neurovascular Conflict

Abstract

Trigeminal neuralgia (TN) is a chronic neuropathic pain condition characterized by brief, intense, and electrical shock-like facial pain. The most common causes of this are due to neurovascular compression of the superior cerebellar artery (SCA). However, as seen in this case report, duplication of the SCA resulting in TN is extremely uncommon. A 63-year-old woman presented with a 1-day history of paroxysmal, shock-like pain on the right side of her face affecting both the ophthalmic (V1) and maxillary (V2) branches of the trigeminal nerve. Each episode of pain would last 1–2 min, occur multiple times each day, and be precipitated by chewing, with resultant ipsilateral tearing. Her past medical history included no trauma, dental disease, or systemic illnesses. Examination of the neurological system revealed all cranial nerves were normal, and there were no facial motor deficits. Magnetic resonance imaging (MRI) of the head-and-neck region with gadolinium enhancement, demonstrated an anomalous duplication of the right SCA where its lower branch compressed and deformed the cisternal portion of the right trigeminal nerve, representing a Grade II neurovascular conflict, with no cerebrospinal fluid visible between the vessel and nerve. Computed tomography scan of the brain demonstrated evidence of chronic ischemic changes and age-related cortical atrophy. Based on the findings from the above diagnostic testing, she was diagnosed with typical TN secondary to neurovascular compression from an anomalous duplicated SCA. She was started on carbamazepine with good symptomatic relief. Duplication of the SCA is a rare anatomical anomaly which may result in symptomatic neurovascular compression of the trigeminal nerve. In cases of suspected neurovascular compression of the trigeminal nerve, high-resolution MRI is necessary to identify these vascular abnormalities and guide the appropriate treatment options.

INTRODUCTION

The symptoms of trigeminal neuralgia (TN) include short, sharp, stabbing pains that occur in the facial area. These pains occur on the trigeminal nerve and can be very painful.[1] In addition to this, they may occur at a time when there is no apparent reason for them to occur. They may occur suddenly or with some warning signs.

TN is an illness which affects the trigeminal nerve. It is a chronic pain disorder. A study found that it occurs about 4 times to 13 out of every 100,000 people each year.[2] Women seem to have more cases than men and older adults are more likely to develop TN than younger adults.

TN is usually caused by a blood vessel compressing the trigeminal nerve near where it enters into the brain. About 75%–80% of these blood vessels are the superior cerebellar arteries (SCAs).[3,4] Typically, the SCAs originate in the top third of the basilar artery and course through the pons before supplying the top portion of the cerebellum. Variations in how the SCAs arise from the basilar artery have been documented extensively in both radiologic and cadaveric studies. The variation that has been documented most frequently is the occurrence of a duplicate SCA. Duplicate SCAs occur in about 10%–26% of cases.[5,6] However, documented evidence of symptomatic neurovascular compression from a duplicated SCA causing TN is scarce in the medical literature.

This article presents the case of a 63-year-old woman who developed classical TN due to neurovascular compression by a duplicated right SCA. High-resolution magnetic resonance imaging (MRI) confirmed the presence of the duplicated right SCA. This case illustrates the need to consider unusual vascular anatomies as possible causes of TN and demonstrates the value of modern neuroimaging in diagnosing and treating patients with TN.

CASE REPORT

A 63-year-old woman visited the emergency department with acute onset, severe, right-sided unilateral facial pain that had been present for 1 day and occurred over the course of several hours. Her pain was intermittent and electric shock-like in quality; distributed over the right side of the forehead and cheek; hence corresponding to the ophthalmic (V1) and maxillary (V2) divisions of the trigeminal nerve. The attacks each lasted from 1 to 2 min and recurred frequently. Each attack was induced by chewing and was accompanied by tearing of the eye on the same side as the pain. Her interictal period remained pain-free. She denied having any symptoms suggesting either facial sensory impairment or muscle weakness. She also denied experiencing double vision, visual disturbances, hearing loss, tinnitus, dizziness, or difficulty in masticating. In addition, she denied experiencing any recent head injury, dental procedures, febrile illness, weight loss, or previous episodes of a similar type.

She reported a past medical history of hypothyroidism, controlled with ongoing medication for the past 3 years.

There were no clinical findings to suggest a diagnosis of multiple sclerosis, connective tissue disease, or chronic infection. She denied smoking, or using alcohol or substances of abuse.

The patient’s vital signs were stable with a blood pressure of 140/90 mmHg, a heart rate of 78 beats/min, a respiratory rate of 17 breaths/min, and an oxygen saturation of 100% on room air. The remainder of her systemic examination of the cardiovascular, pulmonary, and gastrointestinal systems was unremarkable.

Neurologically, the patient was awake, alert, and oriented to person, place, and time. All higher-order cognitive functions were intact. On cranial nerve examination, all cranial nerves were intact bilaterally. Facial sensations in all three branches of the trigeminal nerve (V1, V2, and V3) were intact bilaterally. Both corneal reflexes were intact. There was no weakness in the muscles of mastication; jaw jerk was normal; there was no facial asymmetry or weakness; the motor system examination demonstrated normal tone, strength (normal 5/5 strength in all muscle groups), and reflexes in all four extremities. Plantars were flexors bilaterally; cerebellar signs including finger-nose testing, heel-shin testing, and dysdiadochokinesia were normal; gait was normal, and there were no signs of meningeal irritation.

Investigations

Laboratory investigations

Complete blood count, renal function tests, liver function tests, thyroid function tests, and serum electrolytes were within the normal limits. Blood sugar levels were normal. Electrocardiogram showed normal sinus rhythm with no evidence of ischemic changes.

Audiometry

Pure-tone audiometry performed on November 19, 2025 revealed mild-to-moderate sensorineural hearing loss at low frequencies bilaterally, with preserved hearing sensitivity overall. There were no signs of significant auditory pathway involvement.

Computed tomography brain plain (November 17, 2025)

A plain computed tomography brain scan taken on November 17, 2025 indicated ill-defined hypodensity in the bilateral periventricular zones, coronal radiate zones, and centrum semiovale that is indicative of chronic ischemia. The ventricular system, cortical sulci, sylvian fissure, and basal cisterns all appeared enlarged as expected for cortical atrophy associated with aging. The cerebellum and brain stem appeared normal without an acute hemorrhage or a mass lesion. No bony fractures were identified.

Magnetic resonance imaging brain with contrast (November 21, 2025)

High-quality MRI scans confirmed a duplication of the Right SCA [Figure 1]. Furthermore, a part of the lower branch of the duplicated right SCA was pressing against and distorting the Trigeminal Nerve that is adjacent to it and there was no cerebrospinal fluid (CSF) between the vessel and nerve, which corresponds to Grade II Neurovascular Conflict as per the Sindou Classification. White Matter Ischemic Lesions were identified in both Frontoparietal areas, being hyperintense on T2/fluid-attenuated inversion recovery Sequences, which are consistent with Grade I Changes by Fazekas. Supratentorial and Infratentorial Neuroparenchyma demonstrated normal signal intensity throughout. There were no obvious focal lesions, acute infarcts, or hemorrhages observed. Normal Sella and parasellar structures were also noted. Mild Prominence of the Ventricular System, Basal Cisterns, and Cortical Sulci were observed; normal flow void of the intracranial vessels were also noted. The visualized portion of orbits and paranasal sinus appeared normal. Both trigeminal nerves demonstrated normal course and Caliber on the contralateral side.

Figure 1.

Magnetic resonance imaging brain constructive interference in steady state showing comression of trigeminal nerve

Diagnosis

Based on the clinical presentation of paroxysmal, unilateral, severe, brief, stabbing facial pain in the distribution of the right trigeminal nerve (V1 and V2 divisions), triggered by innocuous stimuli (chewing), with pain-free intervals, and neuroimaging evidence of neurovascular compression by a duplicated right SCA, a diagnosis of Classical TN due to duplication of right SCA with Grade II neurovascular conflict was established.

MANAGEMENT

The patient was started on Carbamazepine at a dose of 100 mg PO BID, which was increased to 200 mg PO BID depending on the patient’s response to the medication and tolerance. Gabapentin 100 mg TID was added as secondary therapy to enhance neuropathic pain control. Rescue analgesics were given for breakthrough pain.

Within 72 h of starting medical therapy, the patient had a noticeable clinical improvement, with decrement in both frequency and intensity of pain episodes. Comprehensive counseling was provided regarding medication adherence and potential side effects (such as dizziness and drowsiness); and the need of regular follow-ups. She was also referred to the neurosurgery department to discuss the possibility of having surgical intervention in case the medical therapy proves to be ineffective. The option of microvascular decompression (MVD) surgery was hence presented as a definitive treatment option if medical management fails or symptoms recur.

The patient was discharged from the hospital sans pain and was advised to continue her medications with frequent outpatient follow-ups.

DISCUSSION

TN is a chronic pain condition that has an impact on the quality of life classical TN is defined in the International Classification of Headache Disorders, Third Edition as recurrent unilateral brief electric shock-like pains that are abrupt in onset and termination, limited to the distribution of one or more divisions of the trigeminal nerve, and triggered by innocent stimuli, with demonstration of neurovascular compression.[1] Our patient fulfilled the diagnostic criteria for classical TN with characteristic paroxysmal pain in V1 and V2 distributions that were triggered by chewing and imaging confirmation of neurovascular compression.

Compression of the trigeminal root entry zone by a neurovascular structure is the most widely accepted pathophysiologic mechanism for classical TN. The SCA is the most common offending vessel.[3,4] Compression of the trigeminal nerve results in focal demyelination, ectopic impulse generation, and ephaptic transmission resulting in the characteristic pain paroxysms.[7] The Sindou Classification grades neurovascular conflict based on the degree of compression; Grade I indicates simple contact without deformation, Grade II shows compression with nerve deformation, and Grade III demonstrates severe compression with distortion.[8] Our patient demonstrated Grade II conflict with visible nerve deformation and absence of CSF between the vessel and nerve, indicating clinically significant compression.

There are anatomical variations of the SCA which are relatively common, and duplication of the SCA is one of the most frequently reported variants.[5,6] Cadaveric studies have documented rates of duplication of the SCA Ranging from 10% to 26%. However, symptomatic neurovascular compression leading to TN from a duplicated SCA is rarely reported. Yaşargil et al. Described SCA variations in detail, noting that duplicated arteries may have different courses and relationships with surrounding neural structures, potentially increasing the risk of neurovascular conflict.[9] In our case, the lower branch of the duplicated SCA was the compressing vessel, highlighting the clinical relevance of this anatomical variant.

MRI sequences including three-dimensional constructive interference in steady state or time-of-flight (TOF) provide excellent visualization of the trigeminal nerve, surrounding vessels, and presence or absence of CSF at the root entry zone.[10] High-resolution MRI provides a gold standard for diagnosing neurovascular compression in TN. Conventional MRI sequences with contrast were sufficient to demonstrate the duplicated SCA and its compressive relationship with the trigeminal nerve in our patient. Identification of vascular anomalies is crucial for surgical planning if MVD is considered.

The differential diagnosis of TN includes secondary causes such as multiple sclerosis, tumors (schwannomas, meningiomas), vascular malformations, and inflammatory or infectious processes.[11] Our patient had no clinical or radiographic features suggestive of demyelinating disease, space-occupying lesions, or other secondary causes, supporting the diagnosis of classical TN. The presence of age-related white matter changes and cortical atrophy on imaging were considered incidental findings related to her age and hypertension rather than contributors to her facial pain.

Medical management remains the first-line treatment for TN, with carbamazepine being the drug of choice, demonstrating efficacy in 70%–80% of patients.[12] other medications including oxcarbazepine, gabapentin, pregabalin, baclofen, and lamotrigine are used as alternatives or adjuncts. Our patient responded well to carbamazepine with gabapentin as adjuvant therapy. However, medical therapy may become less effective over time, or patients may develop intolerable side effects, necessitating alternative interventions.

MVD is considered the most effective surgical treatment for medically refractory classical TN, with Success Rates of 80%–90% and low recurrence rates.[13] The procedure involves identifying and separating the offending vessel from the trigeminal nerve with interposition of teflon felt or other material. In cases of vascular anomalies such as duplicated SCA, careful preoperative imaging assessment and intraoperative identification of both arterial branches are essential to ensure adequate decompression.[14] Other surgical options include percutaneous procedures (radiofrequency thermocoagulation, glycerol rhizolysis, balloon compression) and stereotactic radiosurgery, which are less invasive but generally associated with higher recurrence rates and sensory complications.[15]

The presence of a duplicated SCA adds complexity to surgical planning. The surgeon must be aware of the vascular anatomy to avoid injury to normal arterial branches while achieving adequate decompression of the compressed nerve. Intraoperative neuromonitoring and meticulous microsurgical technique are essential to minimize complications such as cerebellar infarction, hearing loss, or facial numbness.

This case highlights the importance of high-quality neuroimaging in patients presenting with characteristic symptoms of TN. Recognition of anatomical vascular variants such as duplicated SCA is important for accurate diagnosis and optimal treatment planning. While medical management is often successful as first-line therapy, patients should be counseled about surgical options, particularly if symptoms are refractory or significantly impact quality of life.

CONCLUSION

The duplication of the SCA represents a relatively rare but clinically relevant anatomical variation that may result in neurovascular compression of the trigeminal nerve and subsequently lead to the development of classical TN. High resolution MRI will allow clinicians to identify vascular anomalies and thus establish a diagnosis of neurovascular compression. In addition, medical management with anticonvulsants represents the initial approach to treating patients with this condition; however, patients who continue to experience refractory symptoms should be considered as candidates for MVD surgery. Clinicians who are responsible for the care of patients with TN will require an understanding of anatomically variable blood vessels to provide the patient with an accurate diagnosis and a rational basis for their treatment decisions.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.