The Neuroradiology Journal 20: 81-84, 2007
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Isolated Unilateral Sixth Nerve Palsy as a Presenting Symptom of Cerebral Aneurysms Report of Two Cases U. ER*, K. FRASER**, G. LANZINO* Departments of * Neurosurgery and ** Radiology, Microneurosurgery Laboratory, Illinois Neurological Institute, University of Illinois College of Medicine at Peoria; Peoria, Illinois, USA
Key words: cranial nerve palsy, intracranial aneurysms, sixth nerve palsy, spontaneous thrombosis
SUMMARY – We describe two patients with intracranial aneurysms who presented with isolated sixth nerve palsy. A 68-year-old woman with gradual onset of horizontal lateral diplopia was found to have a giant aneurysm at the junction of the petrous and cavernous portion of the internal carotid artery. A 58-year-old man presented with gradual onset of occipital pain followed by a sixth nerve palsy. He was found to have a distal anterior inferior cerebellar artery aneurysm which spontaneously thrombosed on subsequent neuroimaging studies. Although uncommon, isolated sixth nerve palsy can be the only neurological sign of an intracranial aneurysm.
Introduction Isolated palsies of the abducens nerve have been associated with a variety of pathological conditions such as diabetes mellitus, hypertension, multiple sclerosis, increased intracranial pressure, intracranial tumors, trauma, postoperative complications, ischemic and hemorrhagic vascular diseases affecting the pons, as well as various inflammatory and infectious disorders 1,2,3. We describe two patients who presented with isolated sixth nerve palsies secondary to direct compression from an intracranial aneurysm. Case Reports Case 1 A 68-year-old woman suffered mild retroorbital pain and subacute onset of double vision secondary to a right sixth nerve palsy. The pain resolved after a few days but the diplopia persisted. A computed tomography (CT) scan revealed a paraclinoid aneurysm (figure 1 A,B). This
was confirmed by cerebral angiography which localized the giant aneurysm at the junction of the petrous with the cavernous portions of the internal carotid artery (ICA) (figure 1C). The patient underwent coil embolization of the aneurysm with >90% obliteration (figure 1D). She was discharged home in stable condition. However, two months later, her diplopia has not improved. Case 2
This 58-year-old man presented with subacute onset of mild left occipital pain. The following day as the pain resolved, he started complaining of double vision. On exam he was found to have isolated sixth nerve palsy. Magnetic Resonance Imaging showed an heterogeneous, approximately 1 cm in diameter, partially enhancing mass on the left side of the pontomedullary junction (figure 2 A,B). A cerebral angiogram showed a partially thrombosed aneurysm of the left anterior inferior cerebellar artery (figure 2 C,D). The aneurysm was treated conservatively and followup MRI and angiography showed spontaneous thrombosis (figure 3 A,B,C). 81
Isolated Unilateral Sixth Nerve Palsy as a Presenting Symptom of Cerebral Aneurysms. Report of Two Cases
A
B
C
D
U. ER
Figure 1 Case 1. Non contrast CT shows a heterogeneously hyperdense mass in the right middle fossa (A). After contrast administration (B) the lesion enhances uniformly. (C) Cerebral angiogram, selective right ICA injection shows a giant paraclinoid aneurysm. The aneurysm was successfully embolized with detachable coils (D).
Ten months later the patient’s diplopia has significantly improved. Double vision persists only in the extreme lateral left position of gaze. Discussion Because of its long course, the sixth nerve is particularly vulnerable to compression from a 82
variety of pathological processes. However, isolated sixth nerve palsy from intracranial aneurysms has rarely been reported 3,4. We describe two patients with isolated sixth nerve palsy secondary to a giant proximal paraclinoid aneurysm and a distal anterior inferior cerebellar artery (AICA) aneurysm, respectively 5,6. These patients were considered to harbor unruptured aneurysms as subarachnoid hemorrhage was ruled out on clinical grounds
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A
C
The Neuroradiology Journal 20: 81-84, 2007
B
D
Figure 2 Case 2. A) Axial T2 MRI shows a 1 cm mass (arrow) adjacent to the left ventral aspect of the pontomedullary junction. B) The lesion enhances brightly after contrast administration. C) Selective left vertebral arteriogram demonstrates a 3 to 4 mm. aneurysm of the left AICA (arrow). The aneurysm is located approximately 2,5 cm. lateral to the origin of the AICA from the proximal basilar artery. The aneurysm is smaller on the angiogram, than the MRI had suggested indicating partial thrombosis. D) Flow within the aneurysm is very slow as indicated by intraaneurysmal stasis of contrast in the late arterial phase.
based on the history of only mild facial or head pain of subacute onset. The proposed mechanism responsible for the sixth nerve dysfunction is stretching of the nerve from the growing aneurysm as the nerve enters the cavernous sinus through Dorello’s canal in the case of the paraclinoid aneurysm. In the case of the patient with the distal AICA aneurysm, the proposed mechanism responsible for the nerve dysfunction is stretching of the nerve from the
acutely expanding aneurysm at its emergence from the pontomedullary sulcus 7. We feel that the mild pain which in both cases preceded the sixth nerve palsy was more likely related to the acute distension of the aneurysms secondary to rapid growth or partial thrombosis. The possibility of an intracranial aneurysm should be considered in patients presenting with isolated sixth nerve palsy especially in the presence of various degrees of head and facial pain. 83
Isolated Unilateral Sixth Nerve Palsy as a Presenting Symptom of Cerebral Aneurysms. Report of Two Cases
A
Figure 3 Case 2. T2-weighted MRI 8 months later. Axial (A) and sagittal (B) does not show any abnormality. Complete thrombosis and resolution of the lesion is confirmed by catheter angiography (C).
U. ER
B
C
References 1 Blumenthal EZ, Gomori JM, Dotan S: Recurrent abducens nerve palsy caused by dolichoectasia of the cavernous internal carotid artery. Am J Ophthal 124: 255-257, 1997. 2 Lemesle M, Beuriat P, Becker F et Al: Head pain associated with sixth-nerve palsy: spontaneous dissection of the internal carotid artery-a case report. Cephalgi 18: 112-114, 1998. 3 Stracciari A, Giucci G, Bianchedi G et Al: Isolated sixth nerve palsy due to intracavernous carotid aneurysm in a young woman. Acta Neurol Belg 88: 148-151, 1998. 4 Weintrub MI, Sananman ML: Giant intracavernous aneurysm and sixth nerve palsy. Canad J Ophtal 6: 223226, 1971. 5 Suzuki K, Meguro K, Wada M et Al: Embolisation of a ruptured aneurysm of the distal anterior inferior cerebellar artery: case report and review of the literature. Surg Neurol 51: 509-512, 1999. 6 Yamakawa H, Hattori T, Tanigawara T et Al: Intracanalicular aneurysm at the meatal loop of the distal
84
anterior inferior cerebellar artery: a case report and review of the literature. Surg Neurol 61: 82-88, 2004. 7 Ziyal IM, Özcan OE, Deniz E et Al: Early improvement of bilateral abducens nerve palsies following surgery of an anterior communicating artery aneurysm. Acta Neurochir 145: 159-161, 2003.
Uygur ER, MD Sogutozu C. 4th Sk. No: 22/7 06510 Ankara, Turkey Tel.: 0090 505 589 23 55 Fax: 0090 312 316 29 29 E-mail: [email protected]
www. centauro. it
Isolated Unilateral Sixth Nerve Palsy as a Presenting Symptom of Cerebral Aneurysms Report of Two Cases U. ER*, K. FRASER**, G. LANZINO* Departments of * Neurosurgery and ** Radiology, Microneurosurgery Laboratory, Illinois Neurological Institute, University of Illinois College of Medicine at Peoria; Peoria, Illinois, USA
Key words: cranial nerve palsy, intracranial aneurysms, sixth nerve palsy, spontaneous thrombosis
SUMMARY – We describe two patients with intracranial aneurysms who presented with isolated sixth nerve palsy. A 68-year-old woman with gradual onset of horizontal lateral diplopia was found to have a giant aneurysm at the junction of the petrous and cavernous portion of the internal carotid artery. A 58-year-old man presented with gradual onset of occipital pain followed by a sixth nerve palsy. He was found to have a distal anterior inferior cerebellar artery aneurysm which spontaneously thrombosed on subsequent neuroimaging studies. Although uncommon, isolated sixth nerve palsy can be the only neurological sign of an intracranial aneurysm.
Introduction Isolated palsies of the abducens nerve have been associated with a variety of pathological conditions such as diabetes mellitus, hypertension, multiple sclerosis, increased intracranial pressure, intracranial tumors, trauma, postoperative complications, ischemic and hemorrhagic vascular diseases affecting the pons, as well as various inflammatory and infectious disorders 1,2,3. We describe two patients who presented with isolated sixth nerve palsies secondary to direct compression from an intracranial aneurysm. Case Reports Case 1 A 68-year-old woman suffered mild retroorbital pain and subacute onset of double vision secondary to a right sixth nerve palsy. The pain resolved after a few days but the diplopia persisted. A computed tomography (CT) scan revealed a paraclinoid aneurysm (figure 1 A,B). This
was confirmed by cerebral angiography which localized the giant aneurysm at the junction of the petrous with the cavernous portions of the internal carotid artery (ICA) (figure 1C). The patient underwent coil embolization of the aneurysm with >90% obliteration (figure 1D). She was discharged home in stable condition. However, two months later, her diplopia has not improved. Case 2
This 58-year-old man presented with subacute onset of mild left occipital pain. The following day as the pain resolved, he started complaining of double vision. On exam he was found to have isolated sixth nerve palsy. Magnetic Resonance Imaging showed an heterogeneous, approximately 1 cm in diameter, partially enhancing mass on the left side of the pontomedullary junction (figure 2 A,B). A cerebral angiogram showed a partially thrombosed aneurysm of the left anterior inferior cerebellar artery (figure 2 C,D). The aneurysm was treated conservatively and followup MRI and angiography showed spontaneous thrombosis (figure 3 A,B,C). 81
Isolated Unilateral Sixth Nerve Palsy as a Presenting Symptom of Cerebral Aneurysms. Report of Two Cases
A
B
C
D
U. ER
Figure 1 Case 1. Non contrast CT shows a heterogeneously hyperdense mass in the right middle fossa (A). After contrast administration (B) the lesion enhances uniformly. (C) Cerebral angiogram, selective right ICA injection shows a giant paraclinoid aneurysm. The aneurysm was successfully embolized with detachable coils (D).
Ten months later the patient’s diplopia has significantly improved. Double vision persists only in the extreme lateral left position of gaze. Discussion Because of its long course, the sixth nerve is particularly vulnerable to compression from a 82
variety of pathological processes. However, isolated sixth nerve palsy from intracranial aneurysms has rarely been reported 3,4. We describe two patients with isolated sixth nerve palsy secondary to a giant proximal paraclinoid aneurysm and a distal anterior inferior cerebellar artery (AICA) aneurysm, respectively 5,6. These patients were considered to harbor unruptured aneurysms as subarachnoid hemorrhage was ruled out on clinical grounds
www. centauro. it
A
C
The Neuroradiology Journal 20: 81-84, 2007
B
D
Figure 2 Case 2. A) Axial T2 MRI shows a 1 cm mass (arrow) adjacent to the left ventral aspect of the pontomedullary junction. B) The lesion enhances brightly after contrast administration. C) Selective left vertebral arteriogram demonstrates a 3 to 4 mm. aneurysm of the left AICA (arrow). The aneurysm is located approximately 2,5 cm. lateral to the origin of the AICA from the proximal basilar artery. The aneurysm is smaller on the angiogram, than the MRI had suggested indicating partial thrombosis. D) Flow within the aneurysm is very slow as indicated by intraaneurysmal stasis of contrast in the late arterial phase.
based on the history of only mild facial or head pain of subacute onset. The proposed mechanism responsible for the sixth nerve dysfunction is stretching of the nerve from the growing aneurysm as the nerve enters the cavernous sinus through Dorello’s canal in the case of the paraclinoid aneurysm. In the case of the patient with the distal AICA aneurysm, the proposed mechanism responsible for the nerve dysfunction is stretching of the nerve from the
acutely expanding aneurysm at its emergence from the pontomedullary sulcus 7. We feel that the mild pain which in both cases preceded the sixth nerve palsy was more likely related to the acute distension of the aneurysms secondary to rapid growth or partial thrombosis. The possibility of an intracranial aneurysm should be considered in patients presenting with isolated sixth nerve palsy especially in the presence of various degrees of head and facial pain. 83
Isolated Unilateral Sixth Nerve Palsy as a Presenting Symptom of Cerebral Aneurysms. Report of Two Cases
A
Figure 3 Case 2. T2-weighted MRI 8 months later. Axial (A) and sagittal (B) does not show any abnormality. Complete thrombosis and resolution of the lesion is confirmed by catheter angiography (C).
U. ER
B
C
References 1 Blumenthal EZ, Gomori JM, Dotan S: Recurrent abducens nerve palsy caused by dolichoectasia of the cavernous internal carotid artery. Am J Ophthal 124: 255-257, 1997. 2 Lemesle M, Beuriat P, Becker F et Al: Head pain associated with sixth-nerve palsy: spontaneous dissection of the internal carotid artery-a case report. Cephalgi 18: 112-114, 1998. 3 Stracciari A, Giucci G, Bianchedi G et Al: Isolated sixth nerve palsy due to intracavernous carotid aneurysm in a young woman. Acta Neurol Belg 88: 148-151, 1998. 4 Weintrub MI, Sananman ML: Giant intracavernous aneurysm and sixth nerve palsy. Canad J Ophtal 6: 223226, 1971. 5 Suzuki K, Meguro K, Wada M et Al: Embolisation of a ruptured aneurysm of the distal anterior inferior cerebellar artery: case report and review of the literature. Surg Neurol 51: 509-512, 1999. 6 Yamakawa H, Hattori T, Tanigawara T et Al: Intracanalicular aneurysm at the meatal loop of the distal
84
anterior inferior cerebellar artery: a case report and review of the literature. Surg Neurol 61: 82-88, 2004. 7 Ziyal IM, Özcan OE, Deniz E et Al: Early improvement of bilateral abducens nerve palsies following surgery of an anterior communicating artery aneurysm. Acta Neurochir 145: 159-161, 2003.
Uygur ER, MD Sogutozu C. 4th Sk. No: 22/7 06510 Ankara, Turkey Tel.: 0090 505 589 23 55 Fax: 0090 312 316 29 29 E-mail: [email protected]
