Abstract
Significance Statement
This study reveals symptomatic compression of both the vestibulocochlear and facial nerves by the draining vein of a developmental venous anomaly (DVA). A developmental venous anomaly is one of most common cerebral vascular malformation. A caput medusa appearance described as a typical feature for this condition is best demonstrated by magnetic resonance (MR) imaging sequences. A large draining vein of a cerebellar developmental venous anomaly may be cause rarely symptomatic compression of the facial and vestibulocochlear nerves. Adequate visualization of the root exit zones of the facial and vestibulocochlear nerves by high resolution MR imaging sequences, such as thin section turbo spin echo T2 and CISS is very important for appropriate therapy planning.
Introduction
A developmental venous anomaly (DVA), also known as venous angioma, is one of most common cerebral vascular malformation. Its incidence has been reported as approximately 0.5–0.7% on magnetic resonance imaging (MR) imaging series. 1 A caput medusa appearance formed by multiple small medullary veins surrounding the large draining vein has been described as a typical feature for this condition. This finding is best demonstrated by MR imaging sequences. Because DVAs are asymptomatic, they do not mostly require intervention. 2
Symptomatic compression (such as hemifacial spasm from compression of the facial nerve and tinnitus from compression of the vestibulocochlear nerve) of a cranial nerve by the draining vein of a cerebellar DVA is extremely rare. 3 -6 We here report unusual imaging features of a cerebellar DVA in a patient with symptomatic compression.
Case Presentation
A 48-year-old male visited our clinic with left hemifacial spasm for six months. He also had a 2-year history of permanent tinnitus in the left ear. His hemifacial spasm affecting left frontal, mental, periocular, and perioral muscles was exacerbating by stress, anxiety and voluntary facial movements. There were no abnormal ocular movements, sensory deficits, hearing disturbance or speech changes. Other neurological examination findings were unremarkable.
To evaluate the etiology of hemifacial spasm and tinnitus, we performed a cerebral MR imaging examination with a 3 T system (Magnetom Skyra; Siemens Healthcare, Erlangen, Germany) using a head coil. In addition to conventional sequences, we also performed constructive interference in steady state (CISS) sequence. Cerebral MR imaging revealed a transparenchymal collecting vein together with caput medusae involving the left cerebellar hemisphere (Figures 1A). The large collecting vein was extending into the left cerebellopontine angle cistern. Magnetic resonance images also demonstrated that the collecting vein was draining upward toward the left petrosal sinus. This vascular lesion was typical for a cerebellar DVA. Thin slice MR imaging scans showed compression of the left facial nerve and contact of the left vestibular nerve by the draining vein of the cerebellar DVA (Figures 1B and Figure 2). For an optimal diagnostic examination, the patient was offered cerebral angiography but he refused this investigation. Consequent axial T2 weighted MR scans (A) show a transparenchymal collecting vein (blue arrow) together with caput medusae (red arrow) in the left cerebellar hemisphere. Axial CISS sequence and its illustration (B) reveal a large collecting vein (blue arrow) and its association with the facial (purple arrow) and vestibulocochlear (yellow arrow) nerves. The collecting vein is compressing the left facial nerve and is contacting of the left vestibular nerve. Consecutive sagittal CISS sequences (A and B) and its illustrations (right below frames) of the right cerebellopontine angle cistern reveal normal course the right facial (purple arrow) and vestibulocochlear (yellow arrow) nerves. Consecutive sagittal CISS sequences (C and D) and its illustrations (left below frames) of the left cerebellopontine angle cistern reveal compression the left facial nerve (purple arrow) and indentation of the left vestibulocochlear nerve (yellow arrow) by the large connecting vein (blue arrow).
The patient was recommended microvascular decompression surgery but he refused. Tinnitus spontaneously recovered in 6 months. For hemifacial spasm, medical treatment with carbamazepine was performed. The hemifacial spasm progressively recovered in the sixth months of medical treatment.
Conclusion
For evaluation of the neurovascular compression, the facial nerve is divided into four anatomical portions as the root exit zone, attached point, transitional zone, and distal cisternal zone.
5
Arterial compression in patients with hemifacial spasm frequently occurs upon the root exit portion of the nerve.
5,6
The severity of neurovascular compression is classified in three grades as mild (only nerve contact), moderate (nerve indentation), and severe (nerve compression and deviation).
5
In our case, there was severe vascular compression of the left facial nerve by draining vein of the cerebellar DVA. Moreover, the large draining vein was contacting the left vestibulocochlear nerve, was compatible with mild neurovascular compression (Figure 3). Illustrative picture demonstrates a large collecting vein and its association with the facial and vestibulocochlear nerves.
Neurovascular compression of a large draining vein of cerebellar DVA can be a rare cause of hemifacial spasm and tinnitus. In patients with symptomatic neurovascular compression, adequate visualization of the root exit zones of the facial and vestibulocochlear nerves by high resolution MR imaging sequences, such as thin section turbo spin echo T2 and CISS is very important for appropriate therapy planning.
ORCID iDs
Hayri Ogul https://orcid.org/0000-0001-5989-3729
Ali Koksal https://orcid.org/0000-0002-4539-8636