Giant Unruptured Middle Cerebral Artery Aneurysm Presenting with Complex Partial Seizure: A Short Review.

Intracranial aneurysm is a rare cause of seizure although few cases may develop new onset seizure following rupture of aneurysm. The causes of seizure in ruptured aneurysm may be caused due to presence of subarachnoid hemorrhage, intracerebral hematoma, infarct due to progressive vasospasm, worsening of hydrocephalus, or even after surgical craniotomy for clipping of aneurysm. However, incidental aneurysm solely presenting with complex partial seizure is not reported in literature. To the best of knowledge of authors, current case represents the first case as incidental aneurysm presenting with seizure and pertinent literature is briefly reviewed.

INTRODUCTION

Seizures as the first presenting symptom of unruptured intracranial aneurysms are uncommon. Dandy first reported unusual association of intracranial aneurysms associated with seizures.[1] Intracranial aneurysms in children accounts for 0.6%–4.5% of all aneurysms.[2] However, etiology of pediatric intracranial aneurysms remains controversial: birth trauma, Moyamoya disease, hypertension, arteriovenous malformation, coarctation of aorta, tuberous sclerosis, and agenesis of corpus callosum had been associated with pediatric aneurysms.[2] Authors present a case of complex partial seizure with unusual presentation of auditory hallucination in a 17-year-old boy with unruptured middle aneurysm. Diagnosis, management, and pertinent literature reviewed briefly.

CASE REPORT

A 17-year-old boy presented with five episodes of severe headache over 3 months, which were associated with bouts of olfactory aura as smell of “burning rubber tires” lasting for <30 s. The headache was not associated with nausea, vomiting, or any alteration of sensorium. He consulted a local physician for headache; simple analgesics were prescribed and got temporary relief. He was further investigated by a neurologist for suspected complex partial seizures, at our center which revealed a giant left middle cerebral artery (MCA) aneurysm. On admission, he was conscious alert with intact memory and speech. Examination of fundi was normal. Rest of the neurological examination was normal. His serum biochemistry, hematological, and coagulation profiles were also within normal limits.

Noncontrast computerized tomography-enhanced scan revealed a large hyperdense mass lesion in middle cranial fossa [Figure 1]. Digital subtraction angiography showed presence of a giant left middle cerebral artery aneurysm filling from left internal carotid injection with a partly thrombosed sac involving M1 and M2 segment of the left middle cerebral artery with a good collateral after ipsilateral cross compression were observed [Figure 2].

Figure 1

Contrast-enhanced computed tomography scan head showing giant middle cerebral aneurysm

Figure 2

Digital subtraction angiography showing partially thrombosed left middle cerebral artery aneurysm

He was planned for surgical intervention; however, parents were not willing and refused any kind of surgical intervention on the current admission despite detailed prognostication, likely due to illiteracy and financial constraints. However, they planned to revisit the hospital later on after an interval of 2 weeks for admission and further management.

DISCUSSION

Pediatric intracranial aneurysms accounts for 0.5%–4.6% of all aneurysms. However, the most common presentation of pediatric intracranial aneurysms is subarachnoid hemorrhage. However, aneurysms presenting as mass effect is less common. The incidence of giant aneurysm in children is higher as compared to adults. Commonly, the pediatric intracranial aneurysms are located at internal carotid artery bifurcations of anterior circulation.[2345]

Temporal lobe epilepsy as a presenting feature of unruptured cerebral aneurysm is unusual, but only few cases have been reported in the literature[567] in adults. However, only one case of 16-year-old female, with carotid artery bifurcation aneurysm, underwent surgical clipping with temporal lobectomy, and amygdilohippocampectomy, is reported in pediatric age group, the aneurysm was incidental and the size was 8 mm × 13 mm located on right carotid artery bifurcation.[8] The current case had episodes of mild headache associated with olfactory hallucinations. The angiography showed giant fusiform aneurysmal.

The exact mechanism of epileptogenesis in pediatric unruptured intracranial aneurysms remains unknown. However, various hypotheses have been suggested in the literature: direct pressure effects, ischemia caused by thromboembolism, and subclinical hemorrhages. The giant aneurysm may compress hippocampal gyrus causing epilepsy is another suggested hypothesis. Other hypothesis is minor recurrent bleeding or leakage from giant aneurysm without clinical manifestation of subarachnoid hemorrhage, which may lead to localized brain injury associated with local glial scarring and acting as an epileptogenic focus.[6] Embolization from aneurysm is considered rare, but cerebral infarction related to emboli from intracranial aneurysm has been reported leading genesis of seizure.[9] Vasogenic edema has also been incriminated as a cause of epilepsy in intracranial aneurysms. Hammoud et al.[10] observed vasogenic edema in the brain parenchyma surrounding the thrombosed intracranial aneurysm is possible related to acute enlargement of thrombosed aneurysm size leading to loss of vasomotor control and ischemia or inflammatory process.

It is documented that obliteration of aneurysm either by surgical or endovascular procedure can lead to resolution of seizure. However, surgical resection along with clipping is advocated if there is permanent change in adjacent brain. Yacubian et al.[7] reported total seizure free period of 15 months during the follow-up after proximal occlusion of posterior cerebral artery and amygdilohippocampectomy. Baeesa et al.[8] also reported complete seizure free for 2 years following surgical clipping of carotid artery bifurcation aneurysm, temporal lobectomy, and amygdilohippocampectomy. Kamrin[5] reported cases, who was operated for MCA aneurysm and also required temporal lobectomy. Patient had only noticed improvement related to seizure frequency reduction over the 10-month follow-up. Surgical aneurismal clipping alone without resection of surrounding brain parenchyma is also associated with good surgical and seizure-free outcome.[56] Lad et al. reported three cases of incidental aneurysms, detected while getting evaluated of temporal lobe epilepsy. Two cases had aneurysm of middle cerebral artery; one ipsilateral to the planned temporal lobectomy and one contralateral aneurysm and rest had PCA aneurysm.[3] Sengupta et al.[6] analyzed five cases of seizure associated with MCA aneurysm. Kamrin analyzed four cases of middle cerebral artery aneurysm associated with seizure, of which three underwent surgical clipping, one case became completely seizure free, and another two had significant reduction in seizure frequency. Still the ideal surgical method of management of seizure associated with intracranial aneurysm remains controversial.[5] With the advent of endovascular treatment, intracranial aneurysm is increasingly managed with such technique. Patankar and Hughes demonstrated surgical coiling of left MCA aneurysm was associated with clinical resolution of olfactory hallucinations, with resolution of temporal lobe signal changes suggestive of edema, or chronic ischemia. Rarely cases evaluated for medically refractory epilepsy can have incidental aneurysm.[11] Patil et al. observed aneurysms generally present with bleed and epileptogenic aneurysms are rare and presented their three cases, 61-year-old, 57-year-old, and 35-year-old persons, harboring unruptured anterior communicating artery aneurysms, presented with seizure and managed surgically.[4] Patil et al. proposed occurrence of the seizure might be related to the large aneurysmal size, presence of thrombus, repeated subclinical micro-bleed and gliosis of surrounding brain parenchyma and further suggested that large thrombosed anterior communicating artery aneurysms should be considered in the differential diagnosis of patients presenting with late onset of seizure in association with a suprasellar lesion on imaging. Surgical clipping offers a fair chance of seizure freedom in selected patients.[4]

CONCLUSION

Epilepsy associated with giant intracranial aneurysms in childhood is an extremely rare event. The authors suggest that every case presented complex partial seizure in association with parasellar mass on neuroimaging, need to be also investigated for the presence of intracranial aneurysm although possibility is very less, very important producing mass effect, and needed to be considered in the differential diagnosis with other space occupying parasellar mass lesion even in the all the pediatric cases and pediatrician and neurosurgeons should be aware about existence of aneurysms.

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Conflicts of interest

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