204
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Hemifacial Spasm Due to Tumor, Aneurysm, or Arteriovenous Malformation Shinji Nagata, M.D., Toshio Matsushima, M .D., Kiyotaka Fujii, M.D ., Masashi Fukui, M.D., and Chiharu Kuromatsu, M .D. Department of Neurosurgery, Neurological Institute, Faculty of Medicine, Kyushu University 60, and Department of Neurosurgery, Kyushu Welfare Pension Hospital, Kitakyushu, Fukuoka 806, Japan
Nagata S, Matsushima T, Fujii K, Fukui M, Kuromatsu C . Hemifacial spasm due to tumor, aneurysm, or arreriovenous malformation. Surg Neurol 1992 ;38 :204-9 . The authors report eight cases of so-called symptomatic hemifacial spasm . They had gross pathological lesions such as a tumor (one epidermoid, one neurinoma, and two meningiomas), vascular malformation (one medullary venous malformation and two arteriovenous malformations), and aneurysm . In all four cases with a tumor, no artery compressed the facial nerve at the root exit zone . In three of the four cases, the hemifacial spasm disappeared after removal of the tumor in contact with the facial nerve . Compression or encasement of the facial nerve by the tumor was the pathogenesis of the hemifacial spasm in these three cases . The remaining case with tumor (tentorial meningioma) did not have a mass or vessel that directly compressed the facial nerve at the root exit zone . However, the hemifacial spasm disappeared after the removal of the tumor . In a case with a medullary venous malformation with arterial component, an engorged draining vein compressed the root exit zone of the facial nerve . In the remaining three vascular cases-two cases of arteriovenous malformation and a case of saccular aneurysm-enlarged feeding arteries and an aneurysm directly compressed the root exit zone of the facial nerve . Not only arterial or venous but also mass compression can cause hemifacial spasm in some symptomatic cases . Surgical decompression of the facial nerve from the causative organic lesion is the primary choice of treatment .
nism in seven of 19 patients presenting with hemifacial spasm . They corrected the symptoms by arterial decompression of the facial nerve with a Gelfoam sponge interposed between the responsible artery and the facial nerve . Because of Jannetta's pioneering work [6,8], it became clear that a redundant artery compressed the facial nerve at the root exit zone (REZ) in most cases of hemifacial spasm . As Gardner and Sava [5] described in 1962, however, gross pathological lesions in the cerebellopontine angle (CPA) can also cause hemifacial spasm . Eight cases of symptomatic hemifacial spasm are presented that show the pathogenesis and the treatment of hemifacial spasm .
Patients and Methods One hundred fifty-eight cases of hemifacial spasm were treated surgically between 1969 and 1990 . Eight of the 158 cases had a neoplastic or vascular mass lesion as the cause of the hemifacial spasm (Table 1) . All eight patients showed hemifacial spasm during the progression of the disease and underwent surgery to the causative organic lesions . We documented the pathogenesis of the hemifacial spasm from our surgical experiences . We have previously reported two cases of arteriovenous malformation (cases 6 and 7) and a case of medullary venous malformation (case 5) as case reports [2,3,171 .
KEY WORDS : Hemifacial spasm ; Tumor ; Vascular malforma-
Summary of Cases
tion ; Aneurysm
Case I
In 1947, Campbell and Keedy [1] first described cases of hemifacial spasm caused by neurovascular compression . Gardner and Sava 151 found arterial compression mecha-
Address reprint requests to : Shinji Nagata, M .D., Department of Neurosurgery, Neurological Institute, Faculty of Medicine, Kyushu University 60, 3-1-1 Maidashi, Higashiku, Fukuoka 812, Japan . Received October', 1991 ; accepted February 12, 1992 . C 1992 by Elsevier Science Publishing Co ., Inc .
A 43-year-old man developed a right hemifacial spasm 4 months before admission . On admission, positive neurological findings were typical phasic and tonic right hemifacial spasm and mild truncal ataxia . There was no facial weakness . Computed tomographic (CT) scan showed a low-density mass in the right CPA (Figure 1 A) . On magnetic resonance imaging (MRI), the lesion was hypointense on TI-weighted image and hyperintense on T2-weighted image (Figure 1 B-D ) . At surgery, an epidermoid tumor completely encasing the facial 0090-3019/92/55 .00
Hemifacial Spasm Due
Table 1 .
to
Surg Neurol 1992 ;38:204-9
Tumor, Aneurysm, or AVM
Summary of Eight Patients with Symptomatic Hemifacial Spasm Hemifacial Spasm
Case 1 2 3 4 5 6 7 8
20 5
AgelSex 43/M 54/F 29/F 621F 35/M 66/M 28/F 70/F
Pathology
Outcome
Pathogenesis
Epidermoid (CPA) Meningioma (CPA) Neurinoma (CPA) Meningioma (tenrorial) MVM (CBL) AVM (CPA) AVM (CBL) Aneurysm (VA-PICA)
Disappeared Disappeared Disappeared Disappeared Disappeared Disappeared Disappeared Disappeared
Encasement of facial nerve Compression of facial nerve Compression of facial nerve Unknown REZ compression by draining vein REZ compression by feeding artery REZ compression by feeding artery REZ compression by aneurysm
Facial Palsy PS
Follow-up
+
Partially improved Partially improved
+ + +
Unchanged
Abbreviations: PS, postoperative state ; CPA, cerebellopontine angle ; MVM, medullary venous malformation : CBL, cerebellar hemisphere ; REZ, root exit zone of the facial nerve ; AVM, arteriovenous malformation; VA, vertebral artery; PICA, posterior inferior cerebral artery .
nerve was subtotally removed . There was no artery compressing the REZ of the facial nerve . The postoperative course was uneventful, and the hemifacial spasm disappeared immediately after surgery, without facial palsy .
Case 2
A 54-year-old woman developed twitching of the left eyelid 3 years before admission . She also had left tinnitus and hearing loss . The left hemifacial spasm had progressed to the left side of the mouth . Neurological examination on admission showed a left hemifacial spasm with mild weakness of the orbicularis oris muscle . CT scan disclosed a nodular enhancing mass in the left CPA . At surgery, the tumor was found to be a meningioma and was totally removed . The facial nerve passed over the granulated nodular surface of the tumor . There was no compressing artery at the REZ of the facial nerve . After surgery, the left hemifacial spasm immediately disappeared, without facial palsy .
Case 3
A 29-year-old woman underwent surgery for a left glossopharyngeal neurinoma inside and outside of the jugular foramen . Two years after surgery, she developed a tonic left hemifacial spasm, which had gradually progressed . There was no facial weakness . CT scan showed a recurrent mass with ring enhancement . At the second operation, the tumor was found to be an extradural growth that compressed the facial nerve . There was no arterial compression at the REZ of the facial nerve . The tumor was removed, and soon after surgery hemifacial spasm disappeared, with mild facial palsy .
Case 4
A 62-year-old woman developed a left hemifacial spasm without facial palsy 1 year before admission . She gradu-
ally developed dysphagia and double vision . CT scan showed a large high-density mass on the suboccipital surface of the cerebellar hemisphere (Figure 2 A) . At surgery, a tentorial meningioma, which compressed the CPA nerves downward, was removed . There were no cross-compressing vessels at the REZ of the facial nerve . There was a definite identation of the vestibular nerve by a hemispheric vein near the entry to the internal acoustic meatus (Figure 2 B) . After surgery, hemifacial spasm immediately disappeared, without facial palsy .
Case 5
A 35-year-old man developed left facial twitching at the age of 12 years . He gradually developed a mild left facial palsy . Because of truncal ataxia and night headache, he was admitted to our service . Contrast-enhanced CT scan and vertebral angiograms showed a huge vascular mass in the left cerebellar hemisphere associated with an aneurysm at the origin of the posterior inferior cerebellar artery (Figure 3) . Angiograms showed increased cerebellar arteries in the delayed arterial phase and, later, an aggregate of large cerebellar veins . This vascular anomaly was interpreted as a medullary venous malformation (MVM) with an arterial component . At surgery, the aneurysm was clipped and the MVM was subtotally removed . The aneurysm did not compress the facial nerve . A markedly engorged draining vein was seen in the CPA, which concealed the facial nerve . After surgery, hemifacial spasm immediately disappeared, leaving a mild facial palsy .
Case 6
A 66-year-old man developed a right hemifacial spasm 7 years before admission . On admission, he showed no neurological deficit except a right hemifacial spasm . Neither CT scan nor MRI showed any definite abnormalities in the posterior fossa, but vertebral angiograms revealed
206
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Figure 1 . Case) (A) Axial CT image showed a low-density mass in the right cerebellopontine cistern . (B) Saggital MRl showed a hypointense mass in the cistern . The mass was homogeneously low on T2-weighted MRI (C) and isointense on intermediate MRI (D) . C
Figure 2 . Case 4 . (A) Axial enhanced CT image showed a homogeneously enhanced mars in the left cerebellar hemisphere, (B) Operative photograph showed a definite indentation of the facial nerve near the entry to the internal acoustic meatu. . However, there was no croucompressing vessel.
Hemifacial Spasm Due to Tumor, Aneurysm, or AVM
Surg Neurol 1992 ;38 : 2 04 -9
207
Figure 3 . Case S . Axial enhanced CT images showed a granular enhanced mass lesion (A) and homogenous cordlike enhancement (B) in the left cerebellar hemisphere. Left vertebral anB giogram showed a fine granular vascular shadow without early arteriovenous shunt in the arterial phase (C). In the venous phase, many medullary veins drained into the engorged vein (D) .
D
an arteriovenous malformation (AVM) in the right CPA . He was discharged without surgery . Twenty days after discharge, he developed subarachnoid hemorrhage due to rupture of an associated aneurysm in the feeding artery . Clipping of the aneurysm and partial obliteration of the feeding arteries of the AVM were done . The enlarged rostral posterior inferior cerebral artery, which was a main feeder of the AVM, compressed the facial nerve at the REZ . After surgery, he had right facial palsy, but it resolved in 6 months . The hemifacial spasm did not occur after surgery . Case 7 A 28-year-old woman developed hemifacial spasm at the age of 20 years . With progression of the facial palsy, the
hemifacial spasm disappeared . A huge AVM was found in the left cerebellar hemisphere . Surgery showed an enlarged feeding artery compressing the facial nerve at the REZ . Though the facial palsy persisted, the hemifacial spasm did not reappear after surgery . Case 8 A 70-year-old woman developed a left hemifacial spasm 6 months before admission . On admission, she had no neurological deficits except left hemifacial spasm . CT scan showed a round high-density mass in the left cerebellopontine cistern (Figure 4 A) . A vertebral angiogram demonstrated a large saccular aneurysm of the left vertebral artery at the origin of the posterior inferior cerebral artery (Figure 4 B) . Clipping of the aneurysm was done .
208
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Nagata et al
Figure 4 . Case 8. (A) Axial enhanced CT scan showed a round high-density mass in the left cerebellopontine cistern . (B) Vertebral angiogram showed a saccutar aneurysm of the left vertebral artery at the origin of the posterior inferior cerebellar artery.
The aneurysm directly compressed the facial nerve at the REZ. The left hemifacial spasm completely disappeared soon after surgery . Discussion Some patients with a CPA tumor or a vascular lesion may show hemifacial spasm as one of their signs. Compression of the facial nerve by tumor is commonly seen in CPA tumors, but the development of hemifacial spasm is uncommon [11,15,18) . Several authors described cases of hemifacial spasm caused by an aneurysm or an AVM [1,3,5,6,8,9,12,13,16,17,19] . The incidence of symptomatic hemifacial spasm in these reports ranges from 0 .4% to 2 .2% : 5 of 229 cases in Jannetta's series [6) (2 .2%), 1 of 223 cases in the series of Kondo et al [10] (0.4%), 3 of 425 cases in the series of Miyazaki and Fukushima [15} (0 .7%), and 7 of 450 cases in the series ofLoeser and Chen [12] (1 .6%) . In our series, the incidence of symptomatic hemifacial spasm was 8 of 158 cases (5 .1 %) . The higher incidence of hemifacial spasm in our series may be due to sampling of the cases . Our series included some cases with striking neurological signs other than hemifacial spasm and a case with transient hemifacial spasm_ CT scan and MRI each are adequate preoperative examinations for patients with hemifacial spasm to exclude a symptomatic lesion . Vertebral angiography is also required when a vascular lesion is suspected . In our eight cases, there were two different causes of hemifacial spasm : mass and vascular compressions . In
tumor cases, there were the encasement (epidermoid case) and uneven compression (meningioma and neurinoma cases) of the facial nerve by tumors . No offending arterial compression was found at the REZ of the facial nerve in our cases . In Jannetta's epidermoid case, a 2 .5cm tumor compressed the facial nerve at its exit zone from the brain stem [6] . In our case, the epidermoid tumor completely encased the facial nerve . The removal of the tumor around the facial nerve resulted in cure of the hemifacial spasm . In vascular cases, an enlarged feeding artery or dilated draining vein of the AVM or MVM (cases 5, 6, and 7) and a pulsating saccular aneurysm (case 8) were considered responsible for the hemifacial spasm . Several authors reported similar arterial compression to the facial nerve in patients with aneurysm [13] or AVM [9,19] . In these cases, the mechanism of hemifacial spasm is the same as that of "essential" hemifacial spasm . Venous compression to the REZ of the facial nerve can also cause the symptoms of hemifacial spasm [6-81 . Transaxonal "short-circuiting" of the neuronal action potential has been suggested as a mechanism of hemifacial spasm [4] . In "essential" hemifacial spasms, the site of arterial compression is usually at the REZ, where the central and peripheral myelin of the facial nerve is joined [201 . Compression of the facial nerve by either a mass or an abnormal vessel may cause symptomatic hemifacial spasm, and in those cases the concept of REZ compression can not always be accepted . In cases with mass compression, decompression of the facial nerve by removing the mass must be the first
Hemifacial Spasm Due to Tumor, Aneurysm, or AVM
Surg Neurol
209
1992 ;38 :204-9
choice of treatment, as in our cases
1, 2,
and
3.
In cases
with arterial compression, decompression of the facial nerve with prosthetic interposition is used . In cases with aneurysm, clipping of the aneurysm may be enough for relief of the facial nerve compression . However, in cases with dissecting [141 or fusiform aneurysm [183, facial nerve decompression with a prosthesis or arterial readjustment may be necessary . This is also true for AVM cases with facial compression with enlarged feeding artery, as in our case 6 and case of Kim et al [9] . In summary, decompression of the facial nerve by removing the compressing mass is the primary choice for the treatment of symptomatic hemifacial spasm . The prosthetic interposition between the artery and the facial nerve, or arterial displacement away from the facial nerve is the alternative choice, particularly in cases with vascular lesions .
References 1 . Campbell E, Keedy C . Hemifacial spasm : a note on the etiology in two cases . J Neurosurg 1947 ;4 :342-7 . 2 . Fukui M . Medullary venous malformation . Mt Fuji Workshop CVD 1988;6 :183-9 (in Japanese) . 3 . Fukui M, Aikou Y, BabaT, Kitamura K . A case of huge cerebellar AVM totally removed by three fractionated operations . Surg Cereb Stroke 1987 ;15 :329-34 (in Japanese) . 4 . Gardner WJ . Concerning the mechanism of trigeminal neuralgia and hemifacial spasm . J Neurosurg 1962 ;19 :947-57 . . 5 Gardner WJ, Says GA . Hemifacial spasm : a reversible pathophysiological stare . J Neurosurg 1962 ;19 :240-7 . 6 . Jannetta PJ . Cranial rhizopathies . In: Yourmans JR, ed : Neurological surgery, vol 6 . Philadelphia : W.B . Saunders, 1982 :3771-84 . 7 . Jannetta PJ . Hemifacial spasm caused by a venule : case report. Neurosurgery 1984 ;14 :89-92 .
8 . Jannetta PJ. Posterior fossa neurovascular compression syndromes other than neuralgias. In : Wilkins RH, Rengachary SS, eds: Neurosurgery . New York : McGraw-Hill, 1985 :1901-6 . 9. Kim Y, Tanaka A, Kimura M, Yoshinaga S, Tomonaga M . Arteriovenous malformation in the cerebellopontine angle presenting as hemifacial spasm. Case report . Neurol Med Chir (Tokyo) 1991 ;31 :109-12 . 10 . Kondo A, Ishikawa J, Itch H, Niiltma K, Kim C, Konishi T . Hemifacial spasm : Its mechanism and operative results by a microvascular decompression for the facial nerve . Neurosurgeons 1983 ;2 :239-49 (in Japanese) . 11 . Levin JM, Lee JE . Hemifacial spasm due to cerebellopontine angle lipoma: case report . Neurology 1987 ;37 :337-9 . 12 . Loeser JD, Chen J . Hemifacial spasm : treatment by microsurgicai facial nerve decompression . Neurosurgery 1983 ;13 :141-6 . 13 . Maroon JC, Lunsford LD, Deeb ZL. Hemifacial spasm due to aneurysmal compression of the facial nerve . Arch Neurol 1978 ;35 :545-6 . 14 . Matsumoto K, SaijoT, KuyamaH, Asari S, Nishimoto A . Hemifacial spasm caused by a spontaneous dissecting aneurysm of the vertebral artery. Case report . J Neurosurg 1991 ;74 :650-2 . 15 . Miyazaki 5, Fukushima T . CP angle epidermoid presenting as hemifacial spasm . No To Shinkei 1983 ;35 :951-5 (in Japanese). 16 . Moore AP . Postural fluctuation of hemifacial spasm . Case report . J Neurosurg 1984 ;60 :190-1 . 17 . Nagata S, Fujii K, Nomura T . Mats ushima T, Fukut M, Yasumori K . Hemifacial spasm caused by CP angle AVM associated with ruptured aneurysm in the feeding artery . Case report . Neurol Med Chir (Tokyo) 1991 ;31 :406-9. 18 . Obrador S, Lopes-zafra JJ . Clinical features of the epidermoids of basal cisterns of the brain . J Neurol Neurosurg Psychiatry 1969 ;32 :450-4 . 19 . Pierry A, Gameron M . Clonic hemifacial spasm from posterior fossa arteriovenous malformation . J Neurol Neurosurg Psychiatry 1979 ;42 :670-2 . 20. Rudy JR, Jannetta PJ . Hemifacial spasm . Ultrastructural changes in the facial nerve induced by neurovascular compression . Surg Neurol 1975 ;4 :369-70 .
Surg Neurol 1992 ;38 :204-9
Hemifacial Spasm Due to Tumor, Aneurysm, or Arteriovenous Malformation Shinji Nagata, M.D., Toshio Matsushima, M .D., Kiyotaka Fujii, M.D ., Masashi Fukui, M.D., and Chiharu Kuromatsu, M .D. Department of Neurosurgery, Neurological Institute, Faculty of Medicine, Kyushu University 60, and Department of Neurosurgery, Kyushu Welfare Pension Hospital, Kitakyushu, Fukuoka 806, Japan
Nagata S, Matsushima T, Fujii K, Fukui M, Kuromatsu C . Hemifacial spasm due to tumor, aneurysm, or arreriovenous malformation. Surg Neurol 1992 ;38 :204-9 . The authors report eight cases of so-called symptomatic hemifacial spasm . They had gross pathological lesions such as a tumor (one epidermoid, one neurinoma, and two meningiomas), vascular malformation (one medullary venous malformation and two arteriovenous malformations), and aneurysm . In all four cases with a tumor, no artery compressed the facial nerve at the root exit zone . In three of the four cases, the hemifacial spasm disappeared after removal of the tumor in contact with the facial nerve . Compression or encasement of the facial nerve by the tumor was the pathogenesis of the hemifacial spasm in these three cases . The remaining case with tumor (tentorial meningioma) did not have a mass or vessel that directly compressed the facial nerve at the root exit zone . However, the hemifacial spasm disappeared after the removal of the tumor . In a case with a medullary venous malformation with arterial component, an engorged draining vein compressed the root exit zone of the facial nerve . In the remaining three vascular cases-two cases of arteriovenous malformation and a case of saccular aneurysm-enlarged feeding arteries and an aneurysm directly compressed the root exit zone of the facial nerve . Not only arterial or venous but also mass compression can cause hemifacial spasm in some symptomatic cases . Surgical decompression of the facial nerve from the causative organic lesion is the primary choice of treatment .
nism in seven of 19 patients presenting with hemifacial spasm . They corrected the symptoms by arterial decompression of the facial nerve with a Gelfoam sponge interposed between the responsible artery and the facial nerve . Because of Jannetta's pioneering work [6,8], it became clear that a redundant artery compressed the facial nerve at the root exit zone (REZ) in most cases of hemifacial spasm . As Gardner and Sava [5] described in 1962, however, gross pathological lesions in the cerebellopontine angle (CPA) can also cause hemifacial spasm . Eight cases of symptomatic hemifacial spasm are presented that show the pathogenesis and the treatment of hemifacial spasm .
Patients and Methods One hundred fifty-eight cases of hemifacial spasm were treated surgically between 1969 and 1990 . Eight of the 158 cases had a neoplastic or vascular mass lesion as the cause of the hemifacial spasm (Table 1) . All eight patients showed hemifacial spasm during the progression of the disease and underwent surgery to the causative organic lesions . We documented the pathogenesis of the hemifacial spasm from our surgical experiences . We have previously reported two cases of arteriovenous malformation (cases 6 and 7) and a case of medullary venous malformation (case 5) as case reports [2,3,171 .
KEY WORDS : Hemifacial spasm ; Tumor ; Vascular malforma-
Summary of Cases
tion ; Aneurysm
Case I
In 1947, Campbell and Keedy [1] first described cases of hemifacial spasm caused by neurovascular compression . Gardner and Sava 151 found arterial compression mecha-
Address reprint requests to : Shinji Nagata, M .D., Department of Neurosurgery, Neurological Institute, Faculty of Medicine, Kyushu University 60, 3-1-1 Maidashi, Higashiku, Fukuoka 812, Japan . Received October', 1991 ; accepted February 12, 1992 . C 1992 by Elsevier Science Publishing Co ., Inc .
A 43-year-old man developed a right hemifacial spasm 4 months before admission . On admission, positive neurological findings were typical phasic and tonic right hemifacial spasm and mild truncal ataxia . There was no facial weakness . Computed tomographic (CT) scan showed a low-density mass in the right CPA (Figure 1 A) . On magnetic resonance imaging (MRI), the lesion was hypointense on TI-weighted image and hyperintense on T2-weighted image (Figure 1 B-D ) . At surgery, an epidermoid tumor completely encasing the facial 0090-3019/92/55 .00
Hemifacial Spasm Due
Table 1 .
to
Surg Neurol 1992 ;38:204-9
Tumor, Aneurysm, or AVM
Summary of Eight Patients with Symptomatic Hemifacial Spasm Hemifacial Spasm
Case 1 2 3 4 5 6 7 8
20 5
AgelSex 43/M 54/F 29/F 621F 35/M 66/M 28/F 70/F
Pathology
Outcome
Pathogenesis
Epidermoid (CPA) Meningioma (CPA) Neurinoma (CPA) Meningioma (tenrorial) MVM (CBL) AVM (CPA) AVM (CBL) Aneurysm (VA-PICA)
Disappeared Disappeared Disappeared Disappeared Disappeared Disappeared Disappeared Disappeared
Encasement of facial nerve Compression of facial nerve Compression of facial nerve Unknown REZ compression by draining vein REZ compression by feeding artery REZ compression by feeding artery REZ compression by aneurysm
Facial Palsy PS
Follow-up
+
Partially improved Partially improved
+ + +
Unchanged
Abbreviations: PS, postoperative state ; CPA, cerebellopontine angle ; MVM, medullary venous malformation : CBL, cerebellar hemisphere ; REZ, root exit zone of the facial nerve ; AVM, arteriovenous malformation; VA, vertebral artery; PICA, posterior inferior cerebral artery .
nerve was subtotally removed . There was no artery compressing the REZ of the facial nerve . The postoperative course was uneventful, and the hemifacial spasm disappeared immediately after surgery, without facial palsy .
Case 2
A 54-year-old woman developed twitching of the left eyelid 3 years before admission . She also had left tinnitus and hearing loss . The left hemifacial spasm had progressed to the left side of the mouth . Neurological examination on admission showed a left hemifacial spasm with mild weakness of the orbicularis oris muscle . CT scan disclosed a nodular enhancing mass in the left CPA . At surgery, the tumor was found to be a meningioma and was totally removed . The facial nerve passed over the granulated nodular surface of the tumor . There was no compressing artery at the REZ of the facial nerve . After surgery, the left hemifacial spasm immediately disappeared, without facial palsy .
Case 3
A 29-year-old woman underwent surgery for a left glossopharyngeal neurinoma inside and outside of the jugular foramen . Two years after surgery, she developed a tonic left hemifacial spasm, which had gradually progressed . There was no facial weakness . CT scan showed a recurrent mass with ring enhancement . At the second operation, the tumor was found to be an extradural growth that compressed the facial nerve . There was no arterial compression at the REZ of the facial nerve . The tumor was removed, and soon after surgery hemifacial spasm disappeared, with mild facial palsy .
Case 4
A 62-year-old woman developed a left hemifacial spasm without facial palsy 1 year before admission . She gradu-
ally developed dysphagia and double vision . CT scan showed a large high-density mass on the suboccipital surface of the cerebellar hemisphere (Figure 2 A) . At surgery, a tentorial meningioma, which compressed the CPA nerves downward, was removed . There were no cross-compressing vessels at the REZ of the facial nerve . There was a definite identation of the vestibular nerve by a hemispheric vein near the entry to the internal acoustic meatus (Figure 2 B) . After surgery, hemifacial spasm immediately disappeared, without facial palsy .
Case 5
A 35-year-old man developed left facial twitching at the age of 12 years . He gradually developed a mild left facial palsy . Because of truncal ataxia and night headache, he was admitted to our service . Contrast-enhanced CT scan and vertebral angiograms showed a huge vascular mass in the left cerebellar hemisphere associated with an aneurysm at the origin of the posterior inferior cerebellar artery (Figure 3) . Angiograms showed increased cerebellar arteries in the delayed arterial phase and, later, an aggregate of large cerebellar veins . This vascular anomaly was interpreted as a medullary venous malformation (MVM) with an arterial component . At surgery, the aneurysm was clipped and the MVM was subtotally removed . The aneurysm did not compress the facial nerve . A markedly engorged draining vein was seen in the CPA, which concealed the facial nerve . After surgery, hemifacial spasm immediately disappeared, leaving a mild facial palsy .
Case 6
A 66-year-old man developed a right hemifacial spasm 7 years before admission . On admission, he showed no neurological deficit except a right hemifacial spasm . Neither CT scan nor MRI showed any definite abnormalities in the posterior fossa, but vertebral angiograms revealed
206
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Figure 1 . Case) (A) Axial CT image showed a low-density mass in the right cerebellopontine cistern . (B) Saggital MRl showed a hypointense mass in the cistern . The mass was homogeneously low on T2-weighted MRI (C) and isointense on intermediate MRI (D) . C
Figure 2 . Case 4 . (A) Axial enhanced CT image showed a homogeneously enhanced mars in the left cerebellar hemisphere, (B) Operative photograph showed a definite indentation of the facial nerve near the entry to the internal acoustic meatu. . However, there was no croucompressing vessel.
Hemifacial Spasm Due to Tumor, Aneurysm, or AVM
Surg Neurol 1992 ;38 : 2 04 -9
207
Figure 3 . Case S . Axial enhanced CT images showed a granular enhanced mass lesion (A) and homogenous cordlike enhancement (B) in the left cerebellar hemisphere. Left vertebral anB giogram showed a fine granular vascular shadow without early arteriovenous shunt in the arterial phase (C). In the venous phase, many medullary veins drained into the engorged vein (D) .
D
an arteriovenous malformation (AVM) in the right CPA . He was discharged without surgery . Twenty days after discharge, he developed subarachnoid hemorrhage due to rupture of an associated aneurysm in the feeding artery . Clipping of the aneurysm and partial obliteration of the feeding arteries of the AVM were done . The enlarged rostral posterior inferior cerebral artery, which was a main feeder of the AVM, compressed the facial nerve at the REZ . After surgery, he had right facial palsy, but it resolved in 6 months . The hemifacial spasm did not occur after surgery . Case 7 A 28-year-old woman developed hemifacial spasm at the age of 20 years . With progression of the facial palsy, the
hemifacial spasm disappeared . A huge AVM was found in the left cerebellar hemisphere . Surgery showed an enlarged feeding artery compressing the facial nerve at the REZ . Though the facial palsy persisted, the hemifacial spasm did not reappear after surgery . Case 8 A 70-year-old woman developed a left hemifacial spasm 6 months before admission . On admission, she had no neurological deficits except left hemifacial spasm . CT scan showed a round high-density mass in the left cerebellopontine cistern (Figure 4 A) . A vertebral angiogram demonstrated a large saccular aneurysm of the left vertebral artery at the origin of the posterior inferior cerebral artery (Figure 4 B) . Clipping of the aneurysm was done .
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Nagata et al
Figure 4 . Case 8. (A) Axial enhanced CT scan showed a round high-density mass in the left cerebellopontine cistern . (B) Vertebral angiogram showed a saccutar aneurysm of the left vertebral artery at the origin of the posterior inferior cerebellar artery.
The aneurysm directly compressed the facial nerve at the REZ. The left hemifacial spasm completely disappeared soon after surgery . Discussion Some patients with a CPA tumor or a vascular lesion may show hemifacial spasm as one of their signs. Compression of the facial nerve by tumor is commonly seen in CPA tumors, but the development of hemifacial spasm is uncommon [11,15,18) . Several authors described cases of hemifacial spasm caused by an aneurysm or an AVM [1,3,5,6,8,9,12,13,16,17,19] . The incidence of symptomatic hemifacial spasm in these reports ranges from 0 .4% to 2 .2% : 5 of 229 cases in Jannetta's series [6) (2 .2%), 1 of 223 cases in the series of Kondo et al [10] (0.4%), 3 of 425 cases in the series of Miyazaki and Fukushima [15} (0 .7%), and 7 of 450 cases in the series ofLoeser and Chen [12] (1 .6%) . In our series, the incidence of symptomatic hemifacial spasm was 8 of 158 cases (5 .1 %) . The higher incidence of hemifacial spasm in our series may be due to sampling of the cases . Our series included some cases with striking neurological signs other than hemifacial spasm and a case with transient hemifacial spasm_ CT scan and MRI each are adequate preoperative examinations for patients with hemifacial spasm to exclude a symptomatic lesion . Vertebral angiography is also required when a vascular lesion is suspected . In our eight cases, there were two different causes of hemifacial spasm : mass and vascular compressions . In
tumor cases, there were the encasement (epidermoid case) and uneven compression (meningioma and neurinoma cases) of the facial nerve by tumors . No offending arterial compression was found at the REZ of the facial nerve in our cases . In Jannetta's epidermoid case, a 2 .5cm tumor compressed the facial nerve at its exit zone from the brain stem [6] . In our case, the epidermoid tumor completely encased the facial nerve . The removal of the tumor around the facial nerve resulted in cure of the hemifacial spasm . In vascular cases, an enlarged feeding artery or dilated draining vein of the AVM or MVM (cases 5, 6, and 7) and a pulsating saccular aneurysm (case 8) were considered responsible for the hemifacial spasm . Several authors reported similar arterial compression to the facial nerve in patients with aneurysm [13] or AVM [9,19] . In these cases, the mechanism of hemifacial spasm is the same as that of "essential" hemifacial spasm . Venous compression to the REZ of the facial nerve can also cause the symptoms of hemifacial spasm [6-81 . Transaxonal "short-circuiting" of the neuronal action potential has been suggested as a mechanism of hemifacial spasm [4] . In "essential" hemifacial spasms, the site of arterial compression is usually at the REZ, where the central and peripheral myelin of the facial nerve is joined [201 . Compression of the facial nerve by either a mass or an abnormal vessel may cause symptomatic hemifacial spasm, and in those cases the concept of REZ compression can not always be accepted . In cases with mass compression, decompression of the facial nerve by removing the mass must be the first
Hemifacial Spasm Due to Tumor, Aneurysm, or AVM
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choice of treatment, as in our cases
1, 2,
and
3.
In cases
with arterial compression, decompression of the facial nerve with prosthetic interposition is used . In cases with aneurysm, clipping of the aneurysm may be enough for relief of the facial nerve compression . However, in cases with dissecting [141 or fusiform aneurysm [183, facial nerve decompression with a prosthesis or arterial readjustment may be necessary . This is also true for AVM cases with facial compression with enlarged feeding artery, as in our case 6 and case of Kim et al [9] . In summary, decompression of the facial nerve by removing the compressing mass is the primary choice for the treatment of symptomatic hemifacial spasm . The prosthetic interposition between the artery and the facial nerve, or arterial displacement away from the facial nerve is the alternative choice, particularly in cases with vascular lesions .
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8 . Jannetta PJ. Posterior fossa neurovascular compression syndromes other than neuralgias. In : Wilkins RH, Rengachary SS, eds: Neurosurgery . New York : McGraw-Hill, 1985 :1901-6 . 9. Kim Y, Tanaka A, Kimura M, Yoshinaga S, Tomonaga M . Arteriovenous malformation in the cerebellopontine angle presenting as hemifacial spasm. Case report . Neurol Med Chir (Tokyo) 1991 ;31 :109-12 . 10 . Kondo A, Ishikawa J, Itch H, Niiltma K, Kim C, Konishi T . Hemifacial spasm : Its mechanism and operative results by a microvascular decompression for the facial nerve . Neurosurgeons 1983 ;2 :239-49 (in Japanese) . 11 . Levin JM, Lee JE . Hemifacial spasm due to cerebellopontine angle lipoma: case report . Neurology 1987 ;37 :337-9 . 12 . Loeser JD, Chen J . Hemifacial spasm : treatment by microsurgicai facial nerve decompression . Neurosurgery 1983 ;13 :141-6 . 13 . Maroon JC, Lunsford LD, Deeb ZL. Hemifacial spasm due to aneurysmal compression of the facial nerve . Arch Neurol 1978 ;35 :545-6 . 14 . Matsumoto K, SaijoT, KuyamaH, Asari S, Nishimoto A . Hemifacial spasm caused by a spontaneous dissecting aneurysm of the vertebral artery. Case report . J Neurosurg 1991 ;74 :650-2 . 15 . Miyazaki 5, Fukushima T . CP angle epidermoid presenting as hemifacial spasm . No To Shinkei 1983 ;35 :951-5 (in Japanese). 16 . Moore AP . Postural fluctuation of hemifacial spasm . Case report . J Neurosurg 1984 ;60 :190-1 . 17 . Nagata S, Fujii K, Nomura T . Mats ushima T, Fukut M, Yasumori K . Hemifacial spasm caused by CP angle AVM associated with ruptured aneurysm in the feeding artery . Case report . Neurol Med Chir (Tokyo) 1991 ;31 :406-9. 18 . Obrador S, Lopes-zafra JJ . Clinical features of the epidermoids of basal cisterns of the brain . J Neurol Neurosurg Psychiatry 1969 ;32 :450-4 . 19 . Pierry A, Gameron M . Clonic hemifacial spasm from posterior fossa arteriovenous malformation . J Neurol Neurosurg Psychiatry 1979 ;42 :670-2 . 20. Rudy JR, Jannetta PJ . Hemifacial spasm . Ultrastructural changes in the facial nerve induced by neurovascular compression . Surg Neurol 1975 ;4 :369-70 .
