A case of unruptured aneurysm of the internal carotid artery presenting as olfactory hallucinations

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1 SNI: Neurovsulr OPEN ACCESS For entire Editoril Bord visit : Editor: Kzuhiro Hongo, M.D., Shinsui University, Mtsomoto, Jpn Cse Report A se of unruptured neurysm of the internl rotid rtery presenting s olftory hlluintions Jiro Akimoto, Norio Ihimsu, Rei Hrok, Shinjiro Fukmi, Mihihiro Kohno Deprtment of Neurosurgery, Tokyo University, Shinjukuku, Tokyo, Jpn E mil: *Jiro Akimoto jiroki@gmil.om; Norio Ihimsu nori33mth@gmil.om; Rei Hrok r9e0i6@yhoo.o.jp; Shinjiro Fukmi sinjifk@gmil.om; Mihihiro Kohno mkouno nsu@umin..jp *Corresponding uthor Reeived: 30 April 17 Aepted: 17 June 17 Pulished: 22 August 17 Astrt Bkground: Olftory hlluintion, symptom of medil temporl loe epilepsy, is rrely ssoited with unruptured intrrnil neurysms. Cse Desription: We enountered this sitution in 70 yer old womn with n unruptured neurysm t the ifurtion of the internl rotid nd posterior ommuniting rtery. We were le to hieve epilepti ontrol y rniotomy lipping nd medil temporl lesionetomy. Conlusion: Aording to our knowledge, previous reports re limited to ses of lrge middle ererl rtery neurysms ompressing the lterl oritofrontl, nd this is pprently the first report of se where olftory hlluintions ourred from diret stimultion of the entorhinl y n internl rotid nd posterior ommuniting rtery ifurtion neurysm. We exmined the pthophysiology underlying the development of olftory hlluintions. We found rniotomy lipping nd fol resetion to e useful from the stndpoint of seizure ontrol. Whether seizure ontrol n lso e otined with intrrnil neurysm oiling should e investigted in the future. Aess this rtile online Wesite: DOI: /sni.sni_134_17 Quik Response Code: Key Words: Nek lipping, olftory hlluintion, resetion of epileptogeni foi, surgery, unruptured neurysm INTRODUCTION Hving olftory hlluintions is symptom of medil temporl loe epilepsy syndrome. It is elieved tht they our from stimultion of the region where the lterl olftory stri psses through the mygdl to the entorhinl in the nterior prhippompl gyrus. In this rtile, we report our experiene with ptient, presenting with olftory hlluintions, who underwent neurysml lipping nd resetion of epilepti foi for n unruptured neurysm of the internl rotid rtery. CASE PRESENTATION The ptient ws 70 yer old womn. She hd n elder sister with oulomotor nerve plsy who hd undergone This is n open ess rtile distriuted under the terms of the Cretive Commons Attriution NonCommeril ShreAlike 3.0 Liense, whih llows others to remix, twek, nd uild upon the work non ommerilly, s long s the uthor is redited nd the new retions re liensed under the identil terms. For reprints ontt: reprints@medknow.om How to ite this rtile: Akimoto J, Ihimsu N, Hrok R, Fukmi S, Kohno M. A se of unruptured neurysm of the internl rotid rtery presenting s olftory hlluintions. Surg Neurol Int 2017;8: Surgil Neurology Interntionl Pulished y Wolters Kluwer - Medknow

2 lipping for n internl rotid rtery neurysm. The ptient ws lso onerned out n neurysm ut hd never experiened severe hedhe. She visited lol lini euse she suddenly developed the symptom of smelling urning ruer, whih ourred few times per week for the previous month. She underwent mgneti resonne imging (MRI) of the hed nd ws found to hve right internl rotid rtery neurysm. She ws then referred nd dmitted to our hospitl. She hd ler onsiousness, without ny prtiulr neurologil defiits or ny normlities in lood hemistry. Even fter hospitliztion, she hd sudden episodes of phntosmi, whih, however, were not ssoited with loss of onsiousness. No ovious spikes were oserved on slp eletroenephlogrm (EEG). On mgneti resonne ngiogrphy (MRA) of the hed, we noted dumell shped neurysm, 10 mm in dimeter, ppered to hve extended from the right internl rotid rtery to piere the medil temporl loe [Figure 1]. Plin T1 weighted MRI reveled n re of high signl intensity in the distl dome of the neurysm, suggesting thromosis. The surrounding rin showed high signl intensity on the T2 weighted imge [Figure 1]. Cererl ngiogrphy reveled tht the prinipl site of the neurysm ws the posterior ommuniting rtery (P om) ifurtion, nd ontrst medium retention ws oserved in the distl dome [Figure 1]. Post ontrst onstrutive interferene in the stedy stte (CISS) imging reveled tht the neurysm dome intruded into the entorhinl sulus nd rehed the mygdl [Figure 1d]. As its long xis nd shpe suggested risk of rupture nd its nture eing n unruptured intrrnil neurysm presenting with olftory hlluintions, the ondition ws determined to e n indition for surgery. d Figure 1: () An originl imge of gdolinium-enhned MR ngiogrphy. A dumell-shped neurysm is intruding into the entorhinl sulus from the right internl rotid rtery. () A T2-weighted horizontl MRI imge. A high signl intensity re suggesting edem round the neurysm is shown in the medil temporl loe. ()The right internl rotid rtery ngiogrphy shows n neurysm with nrrow nek t the posterior ommuniting rtery ifurtion. (d) A oronl setion imge of gdolinium-enhned T2-weighted CISS MRI. The tip of the neurysm rehes the viinity of the mygdl nulei Surgery A right pterionl rniotomy ws performed using trns sylvin pproh to the right internl rotid rtery. After onfirmtion of the presene of the neurysm, 16 eletrodes were pled over the lterl temporl loe to reord temporl ortil EEG. As result, ler spike dishrges were deteted from some eletrodes [Figure 2]. After rehing the neurysm, we found tht the P om ws seprted from the proximl nek, nd the right oulomotor nerve ws ompressed. The neurysm intruded into the medil temporl loe, whih ws slightly disolored to rownish tone [Figure 2]. We performed nek lipping fter onfirming the position of the nterior horoidl rtery distl to the neurysm nek s well s the positions of the P om nd its perfortors. Therefter, the disolored medil temporl loe ws inised nd reseted, nd thromosis of the distl dome ws onfirmed [Figure 2]. After dething it irumferentilly, we removed the dome s mss t position slightly distl to the lip. Therefter, the medil temporl loe ws reseted y spirtion until normlly olored white mtter ws exposed, nd the posterior ererl rtery ws visully identified t the ottom [Figure 2d]. After these proedures, EEG ws gin reorded from the lterl temporl. In the EEG, lthough slow wves ppered in prt, no ovious spikes were deteted, nd the opertion ws ompleted [Figure 2e]. Pthology The reseted neurysm wll ws pseudoneurysm without n rteril wll struture; the internl elsti lmin ws omposed of thin firous tissue with mild inflmmtory response [Figure 3]. The exised temporl loe tissue showed degenerted, gnglion ell like neurons in the, nd edemtous hnges in the white mtter ompnied y the presene of retive stroytes. There were no hnges suggestive of n old hemorrhge [Figure 3]. Postopertive ourse The ptient hd n uneventful linil ourse, nd the olftory hlluintions resolved. Postopertive 3D CT ngiogrphy onfirmed the dispperne of the neurysm nd the pteny of the P om [Figure 3]. In ddition, ontrst enhned MRA showed the extent of resetion of the medil temporl loe. She ws dishrged multing independently under tretment with orl levetiretm 1000 mg, whih ws disontinued t the sixth postopertive month. Sine then, she hs not experiened seizures. DISCUSSION A study nlyzing 1423 ptients with prtil epilepsy reported tht olftory hlluintion ws rre symptom, ourring in only 13 ptients (0.9%). [1] Of the 13 ptients,

3 d e Figure 2: () Cler spikes were evoked in severl eletrodes of intropertive ortil EEG. () The exposed neurysm intruded into the right medil temporl loe, where rownish disolortion (rrow) ourred (*right oulomotor nerve). () After dethment of the posterior ommuniting rtery nd its perfortors, nek lipping ws performed, followed y ortiotomy of the rownish disolored re of the medil temporl loe. With these proedures, the thromosed distl dome (*) ws exposed. (d) After resetion of the neurysml dome, the right medil temporl loe ws removed until normlly olored white mtter ws exposed. (e) No ovious spikes were deteted on the intropertive ortil EEG fter removl of the medil temporl loe Figure 3: () The reseted neurysm wll ws pseudoneurysm without n rteril wll struture. () The medil temporl loe reseted t the sme time showed degenerted neurons nd edemtous tissue ompnied y gliosis. There ws no ler hemosiderin deposition. () Postopertive 3D-CT ngiogrphy onfirmed the omplete dispperne of the neurysm nd presented fvorle imge of the posterior ommuniting rtery 10 ptients developed tumors in the re from the entorhinl to the mygdl. In the remining 3 ptients, the use of olftory hlluintion ws onsidered to e medil temporl slerosis. [1] In study where temporl loetomy ws performed in 217 ptients with intrtle temporl loe epilepsy, 12 ptients (5.5%) were found to hve olftory ur. The use in these ptients ws onsidered to e medil temporl slerosis in 7 ptients, tumors in 4 ptients, nd rteriovenous mlformtion in 1 ptient. [2] Unruptured intrrnil neurysms rrely led to prtil seizures. Aording to study onduted y Solomon et l. in 202 ptients with unruptured intrrnil neurysms, 5% of the ptients hd seizures, nd ll of them hd lrge neurysms of 1 m in dimeter. [7] On the other hnd, study onduted y Currie et l. in 666 ptients with temporl loe epilepsy reported tht the use ws unruptured intrrnil neurysm in only 1 ptient. [3] There hve een rre reports, i.e., only few ses, of olftory ur used y unruptured intrrnil neurysms [5,6,8] [Tle 1]. As desried erlier, for the development of olftory ur, it is neessry to pply stimultion to some prt of the olftory neurl network. Therefore, it is resonle to onsider n neurysm tht is in ontt with the olftory trt, lterl olftory stri, mygdl, prhippompl gyrus, or entorhinl to e the use. On the other hnd, it hs een lrified tht the oritofrontl in the frontl loe is involved prtiulrly in olftory disrimintion s the seondry olftory. In ft, s to ll the previously reported ses listed in Tle 1, the lterl oritofrontl ws onsidered to e stimulted y lrge middle ererl rtery neurysm exeeding 1 m in dimeter. Therefore, this is pprently the first report of se where n internl rotid nd posterior ommuniting rtery ifurtion neurysm extended lterlly, growing in size to 1 m, nd intruded into the entorhinl, therey using olftory ur. In the present se, the ptient omplined of n unusul smell of something like urning ruer. However, the nture of the unusul smell pereived ws ompletely different from the smell reported in the ses of middle ererl rtery neurysms, suh s the sweet plesnt smell of flowers, sweet fruits, or roses. Interestingly, this my reflet differene in the ffeted site.

4 Tle 1: Summry of linil piture of unruptured intrrnil neurysms presenting with olftory hlluintions Author Age/ Sex Lotion Size (mm) Type of olftory hlluintion Whittle (1985) 52/M MCA 25 Felt n overwhelming plesnt smell, likened to roses 48/F MCA 40 Felt putrid smell, likend to peeled hokos Mizuuhi (1999) 49/F MCA 10 Felt sweet plesnt smell, likened to flowers or sweet fruits Miele (2004) 55/F MCA 15 Felt pereption of strnge smell Presented se (2017) 70/F IC PC 12 Felt smell of urnt ruer Affeted rin temporl Mehnism Tretment Postopertive AED Seizure outome Fol Clipping ompression Lterl Fol Wrpping oritofrontl ompression Lterl Fol Clipping oritofrontl ompression temporl temporl Sulinil hemorrhge Fol ishemi Clipping Mintenne of phenytoin Controlled nd methylphenoritone Mintenne of phenytoin, methylphenoritone, rmzepine, sodium vlprote Administrtion of zonismide for two yers Mintenne of rmzepine Clipping nd Administrtion of resetion of levetiretm for six epileptogeni months fous AED: Anti epilepti drug, MCA: Middle ererl rtery, IC PC: Internl rotid rtery distl to the origin of the posterior ommuniting rtery Unontrolled Cure Controlled Cure Regrding the mehnism underlying the development of prtil seizures due to unruptured intrrnil neurysms, potentil uses re onsidered to e diret ompression stimultion of the y n neurysm, minor hemorrhge from n neurysm, or infrtion used y emoli from n neurysm. [5,6] However, the present se is hrterized y ortil neuron degenertion nd edem with gliosis, with no ler hemosiderin deposition in the edemtous rin prenhym surrounding the neurysm, suggesting tht ishemi hnges re primrily involved. On the other hnd, the hnges round the neurysm on the MRI were restrited within very nrrow region. Therefore, the primry use is onsidered to e lol irultory disturne resulting from the ompression y the neurysm, rther thn emolism from the neurysm. Mjority of ptients with unruptured intrrnil neurysms presenting with prtil seizures progress to generl onvulsions. The ourrene of seizures in these ptients is onsidered wrning sign of impending rupture of the neurysm. Therefore, neurysml lipping is performed in most ptients. However, the lipping lone, whih n prevent the rupture, is onsidered indequte from the stndpoint of seizure ontrol. Therefore, in the present se, we performed ortil EEG monitoring, reseted the neurysm following lipping, nd then onfirmed the dispperne of spikes on the ortil EEG fter the mrosopilly disolored re ws ompletely removed. Consequently, the ptient hieved seizure free stte t the sixth postopertive month. In the literture, study y Whittle et l. [8] in 4 ptients with middle ererl rtery neurysms presenting with fol seizures reported tht 2 ptients hieved seizure free stte fter lipping nd fol resetion, wheres seizures ould not e ontrolled in ptients reeiving surgil wrpping only. Miele et l. [5] lso reported tht seizure ontrol n e otined only y redution of the mss effet of n neurysm nd removl of tissue degenerted y ompression, whih is deteted y MRI. On the other hnd, Ku et l. [4] reported ptients with middle ererl rtery neurysms presenting with fol seizures in whom seizure free stte ws hieved within 4 yers y oil emoliztion only. These reports suggest the possiility tht seizure ontrol n e otined y eliminting pulstile ompressive fore pplied to the round the neurysm. To urtely determine whether resetion of epilepti foi is required for ontrol of seizures in suh ses would require rndomized ontrolled tril. Considering the rrity of these lesions, it is unlikely suh tril will ever e onduted, nd therefore, deisions regrding the mngement of these ptients will need to e mde on n individul sis. Finnil support nd sponsorship Nil. Conflits of interest There re no onflits of interest. REFERENCES 1. Ahry V, Ahry J, Luders H. Olftory epilepti urs. Neurology 1998;51: Chen C, Shih YH, Yen DJ, Lirng JF, Guo YC, Yu HY, et l. Olftory urs in ptients with temporl loe epilepsy. Epilepsi 2003;44: Currie S, Hethfield KWG, Henson RA, Sott DF. Clinil ourse

5 nd prognosis of temporl loe epilepsy survey of 666 ptients. Brin 1971;94: Ku R, Krup P, Okov L, Rektor I. Unruptured intrrnil neurysm s use of fol epilepsy: An exellent postopertive outome fter intr rteril tretment. Epilepti Disord 2004;6: Miele VJ, Bendok BR, Btjer HH. Unruptured neurysm of the middle ererl rtery presenting with psyhomotor seizures: Cse study nd review of literture. Epilepsy Behv 2004;5: Mizouhi M, Ito N, Tnk C, Sko K, Sumi Y, Sski T. Unidiretionl olftory hlluintion ssoited with ipsilterl unruptured intrrnil neurysm. Epilepsi 1999;40: Solomon RA, Fink ME, Pile Spellmn J. Surgil mngement of unruptured intrrnil neurysms. J Neurosurg 1994;80: Whittle IR, Allsop JL, Hlmgyi GM. Fol seizures: An unusul presenttion of gint intrrnil neurysms: A report of four ses with omments on the nturl history nd tretment. Surg Neurol 1985;24: