Arteriovenous malformation surrounding the trigeminal nerve--case report

Fatal hemorrhagic complication after coil embolization of a petrosal arteriovenous shunt

BACKGROUND

Cerebello-pontine AVMs (CPAVMs) and petrous apex dural arteriovenous fistulae (DAVFs) are rare and sometimes difficult to distinguish. We report a fatal hemorrhagic complication after coil embolization of the petrosal vein draining a trigeminal AVM misdiagnosed as a DAVF.

CASE PRESENTATION

A 73-year-old woman with a petrous apex arteriovenous shunt with dual dural and pial arterial supply presented with posterior fossa hemorrhage. The draining petrosal vein was catheterized and coiled via the superior petrosal sinus. Two episodes of contrast extravasation occurred during coiling, but the lesion was completely occluded at the end of the procedure. The patient developed a fatal posterior fossa hemorrhage in the recovery room. Microscopic pathology revealed numerous dilated vessels within the trigeminal nerve.

CONCLUSION

CPAVMs and DAVFs with pial drainage should be distinguished pre-operatively. Occlusion of a pial vein (as opposed to a sinus) in the treatment of an arteriovenous shunt carries hemorrhagic risk if a liquid embolic agent is not used to completely occlude all pathological vessels.

Arteriovenous malformation of the trigeminal nerve root presented with venous congestive edema of the medulla oblongata and upper cervical cord: illustrative case

BACKGROUND

Arteriovenous malformation (AVM) of the trigeminal nerve root (TNR) is a rare subtype of the lateral pontine AVM. Most of them are diagnosed when they bleed or exert trigeminal neuralgia. Venous congestive edema is a rare phenomenon caused by TNR AVMs.

OBSERVATIONS

An 82-year-old man was admitted with progressive limb weakness and dysphasia. Magnetic resonance imaging (MRI) revealed extensive edema of the medulla oblongata and the upper cervical cord with signal flow void at the C3 anterior spinal cord. Vertebral angiography revealed a small nidus fed mainly by the pontine perforating arteries (PPAs). The anterior pontomesencephalic vein (AMPV) was dilated, functioning as the main drainage route. This suggests that venous hypertension triggered the brainstem and upper cervical cord edema. MRI with gadolinium enhancement showed that the nidus was located around the right TNR. Because the nidus sat extrinsically on the pial surface of the right TNR’s base, microsurgical obliteration with minimum parenchymal injury was achieved. Postoperative MRI showed disappearance of the brainstem and cervical cord edema with improved clinical symptoms.

LESSONS

TNR AVM is rarely associated with brainstem and upper cervical cord edema caused by venous hypertension of the congestive drainage system.

Embolization of ruptured arteriovenous malformations in the cerebellopontine angle cistern

Among brainstem arteriovenous malformations (AVMs), there exist small AVMs predominantly located in the cerebellopontine angle cistern (CPAC) with minimal extension into the pial surface of the brainstem. However, previous studies of CPAC AVMs did not particularly discuss the role of embolization in the treatment of these lesions. This study was conducted to clarify the effectiveness and validity of embolization in the treatment of CPAC AVMs. We retrospectively reviewed five patients with CPAC AVMs who underwent endovascular treatment. These patients were treated with embolization followed by open surgery or gamma knife (GK) radiosurgery. Radiological findings and clinical course for these patients were then assessed. All five patients presented with a hemorrhage. Angiography revealed that the main feeder contained a dilated pontine perforating artery in all cases. Embolization through the dilated pontine perforating artery effectively reduced shunt flow within the nidus or obliterated associated aneurysms. Magnetic resonance imaging showed infarction on the lateral pons in four patients, one of which developed transient mild dizziness and mild ataxia of the right side. Subsequent open surgery was performed in three patients, and GK radiosurgery was performed in two patients without complications. At the end of the follow-up period, all patients demonstrated favorable outcomes. Postoperative rebleeding did not occur in any of the patients. Disappearance of the AVM was confirmed in four patients, except in the one patient treated with GK. Although ischemic complications should be noted, embolization of CPAC AVMs may be an appropriate treatment option to reduce the risk of subsequent surgery or radiosurgery.

Trigeminal neuralgia caused by brain arteriovenous malformations: A case report and literature review

Few cases of trigeminal neuralgia (TGN) induced by brain arteriovenous malformations (bAVMs) have previously been reported. The present case report described one case of TGN caused by bAVMs in a 32-year-old male patient who suffered from recurrent pain in his right cheek for a period of two years, for whom the seizure frequency and duration of pain increased for 6 months. Magnetic resonance imaging was performed, which demonstrated flow-void signals in the abnormal vessels in the right cerebellopontine angle. Subsequent digital subtraction angiography confirmed the diagnosis of bAVMs, and showed the nidus was fed by the right superior cerebellar and the right anterior inferior cerebellar, and drained into the adjacent venous sinuses on the same side. The patient underwent an interventional embolization treatment. TGN was completely relieved following embolization of the majority of the bAVMs. Pain relief may be associated with blocking of the pulsatile compression of the feeding arteries of the bAVMs, the arterialized draining veins or the malformed niduses following embolization, which is similar to the effects induced by microvascular decompression surgery of the trigeminal nerve. In the present case study and review, the underlying mechanism and treatment strategy of TGN caused by bAVMs were discussed in the context of present case, and a literature review was carried out.

Clinical characteristics of arteriovenous malformations in the cerebellopontine angle cistern

OBJECTIVE Arteriovenous malformations (AVMs) in the cerebellopontine angle cistern (CPAC) are specific lesions that can cause neurovascular compression syndromes as well as intracranial hemorrhage. Although case reports describing the CPAC AVMs, especially those presenting with trigeminal neuralgia (TN), have been accumulating by degrees, the pathophysiology of CPAC AVMs remains obscure. The authors' purpose in the present study was to evaluate the clinical and radiographic features of CPAC AVMs as well as the treatment options. METHODS This study defined a CPAC AVM as a small AVM predominantly located in the CPAC with minimal extension into the pial surface of the brainstem and closely associated with cranial nerves. All patients with CPAC AVMs treated in the authors' affiliated hospitals over a 16-year period were retrospectively identified. Clinical charts, imaging studies, and treatment options were evaluated. RESULTS Ten patients (6 men and 4 women), ranging in age from 56 to 77 years (mean 65.6 years), were diagnosed with CPAC AVMs according to the authors' definition. Six patients presented with hemorrhage, 3 with TN, and the remaining patient developed a hemorrhage subsequent to TN. Seven AVMs were associated with the trigeminal nerve (Group V), and 3 with the facial-vestibulocochlear nerve complex (Group VII-VIII). All patients in Group VII-VIII presented with the hemorrhage instead of hemifacial spasm. Regarding angioarchitecture, the intrinsic pontine arteries provided the blood supply for all CPAC AVMs in Group V. In addition, 5 of 7 AVMs with hemorrhagic episodes accompanied flow-related aneurysms, although no aneurysm was detected in patients with TN alone. With respect to treatment, all patients with hemorrhagic presentation underwent Gamma Knife surgery (GKS), resulting in favorable outcomes except for 1 patient who experienced rebleeding after GKS, which was caused by the repeated rupture of a feeder aneurysm. The AVMs causing TN were managed with surgery, GKS, or a combination, according to the nidus-nerve relationship. All patients eventually obtained pain relief. CONCLUSIONS Clinical symptoms caused by CPAC AVMs occur at an older age compared with AVMs in other locations; CPAC AVMs also have distinctive angioarchitectures according to their location in the CPAC. Although GKS is likely to be an effective treatment option for the CPAC AVMs with hemorrhagic presentations, it seems ideal to obliterate the flow-related aneurysms before performing GKS, although this is frequently challenging. For CPAC AVMs with TN, it is important to evaluate the nidus-nerve relationship before treatment, and GKS is especially useful for patients who do not require urgent pain relief.

Arteriovenous malformation of the vestibulocochlear nerve

We describe a rare case of an arteriovenous malformation (AVM) embedded in the vestibulocochlear nerve presenting with subarachnoid hemorrhage (SAH) treated by microsurgical elimination of the main feeding artery and partial nidus volume reduction with no permanent deficits. This 70-year-old woman was incidentally diagnosed 4 years previously with two small unruptured tandem aneurysms (ANs) on the right anterior inferior cerebral artery feeding a small right cerebellopontine angle AVM. The patient was followed conservatively until she developed sudden headache, nausea and vomiting and presented to our outpatient clinic after several days. Magnetic resonance imaging demonstrated findings suggestive of early subacute SAH in the quadrigeminal cistern. A microsurgical flow reduction technique via clipping between the two ANs and partial electrocoagulation of the nidus buried within the eighth cranial nerve provided radiographical devascularization of the ANs with residual AVM shunt flow and no major deficits during the 2.5 year follow-up. This is only the second report of an auditory nerve AVM. In the event of recurrence, reoperation or application of alternative therapies may be considered.

Trigeminal neuralgia secondary to arteriovenous malformations of the posterior fossa

BACKGROUND

Trigeminal neuralgia secondary to a posterior fossa AVM has been seldom reported in the literature. Most of the cases have been published on a case report basis, and there is not a general agreement about the best way of treatment.

METHODS

In this work, we analyze our experience with 5 cases of TN secondary to a posterior fossa AVM, treated at the Division of Neurosurgery from the National Institute of Neurology and Neurosurgery, "Manuel Velasco Suarez," Mexico City, Mexico, from January 1985 to December 2004.

RESULTS

Trigeminal neuralgia associated with an AVM occurred in 1.3% of 375 brain AVMs and 9.8% of 37 posterior fossa AVMs. All had received drug therapy unsuccessfully, and 2 of them underwent a percutaneous thermocoagulation without solving the neuralgia. In 4 patients, a microvascular decompression was completed with excellent results.

CONCLUSIONS

Even when different ways of treatment have been reported, it seems that percutaneous procedures (glycerol injection, thermocoagulation, or microcompression of the gasserian ganglia) give variable clinical results. The reported experience and our own results support the microvascular decompression of the trigeminal nerve as the best treatment whenever the total excision of the AVM cannot be accomplished.