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Major congenital anomalies of the internal carotid artery: agenesis, aplasia and hypoplasia
International Journal of Pediatric Otorhinolaryngology 49 (1999) 69 – 76
Case report
Major congenital anomalies of the internal carotid artery: agenesis, aplasia and hypoplasia P. Claro´s *, R. Bandos, I. Gilea, A. Claro´s Jr., A. Capdevila, J. Garcı´a Rodrı´guez, A. Claro´s Clı´nica Claro´s, Los Vergos 31, 08017 Barcelona, Spain Received 6 August 1998; received in revised form 8 January 1999; accepted 9 January 1999
Abstract Agenesis, aplasia and hypoplasia of the internal carotid arteries (ICA) are rare congenital disorders with few descriptions in the otorhinolaryngological literature. We present two cases of major abnormalities of the ICA, one with isolated hypoplasia and another with agenesis associated with ear malformation and facial palsy. We briefly review the normal anatomy and discuss the main aspects of these malformations. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Internal carotid artery abnormalities; Carotid artery displasia; Congenital facial palsy; Ear malformation association
1. Introduction Congenital malformations of the internal carotid artery (ICA) — agenesis, aplasia and hypoplasia—are rare morphological malformations. Tode [7] described for the first time, in 1787, a
* Corresponding author. Fax: +34-93-2803332.
case of agenesis of the ICA, and nearly 100 cases have been reported to date. Most of these are in the radiological and neurological literature, although knowledge of these pathologies is also important for otorhinolaryngologists. In our two cases the initial focus of investigation was the ear, the internal carotid malformation was diagnosed subsequently. Both of them are children, although most of the cases described are in older patients, with frequent symptoms of cerebrovascular disorders.
0165-5876/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 1 6 5 - 5 8 7 6 ( 9 9 ) 0 0 0 1 2 - 9
70
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
1.1. Case 1 A 14-month old boy was referred to our E.N.T. Department due to a malformation of the right
external and middle ear associated with congenital facial palsy (Fig. 1). Clinical examination showed microtia and absence of the external auditive meatus, with a total facial palsy. Behavioural au-
Fig. 1. Frontal aspect of the patient (case 1).
Fig. 2. CT study revealing the absence of the right carotid canal in the skull base (case 1).
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
71
Fig. 3. Angio-resonancy showing a type D (Lie) collateral blood flow (case 1).
diometry showed a 70 dB threshold on the right side, and the brainstem evoked response audiometry revealed a 90 dB threshold, with a V- wave peak-latency of 6.67 ms, compatible with a conductive hearing loss. The left ear showed no alteration. The CT study revealed a malformation of the right external conduct associated with hypoplasia of the middle ear and mastoid, and an anteriorized facial nerve canal. At the base of the skull, the absence of the right carotid canal was observed (Fig. 2), then a complementary examination, with MR and angio-MR imaging, was performed. In these studies, the right ICA was absent, and the angio-MR confirmed the absence of the cervical, petrous and cavernous portion of the right ICA, and a left-right shunt through a transsellar vessel was observed supplying the affected side (Fig. 3). To date, at the age of 2 years, the patient has showed no other alteration, and at the right age he may undergo surgery for the ear malformation.
1.2. Case 2 A 8-year-old boy presented with hypoacusis in the right ear. In the otoscopy, a pulsatile red mass was observed in the hypotympanum, without associated tinnitus. The audiometry revealed a mild conductive hearing loss (15 dB), and the tympanometry test was normal. In the left ear, no alteration was observed. Then, a CT was performed, revealing a mass in the promontory involving the round window (Fig. 4), performing the traject of the inferior tympanic artery. Furthermore the observation of the skull base showed a hypoplasic right carotid canal, suggesting a malformation of the ICA. The hypotesis of a compensatory enlarged inferior tympanic artery was confirmed by arteriography. As a complementary study, the MR showed an ischemic lesion in the right lenticular nucleus, of 2×2 × 1 cm (Fig. 5), and another, smaller, in the ipsilateral caudal nucleus, although the patient presented no neurological symptoms. In angio-MR, the hypo-
72
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
plasy of the ICA was confirmed, and an enlarged anterior communicating artery could be seen, supplying the anterior and the middle cerebral arteries (Fig. 6).
2. Discussion
2.1. Embryology and anatomy The ICA originates in the third aortic arch, and it remains controversial whether the common and external carotidies have the same third aortic arch origin or if they are originated from the aortic sac [8,9]. At the fourth week of gestation the ICA is well defined, and the carotid canal is formed in the skull base after and in depending of the primordial ICA [9,10]. The external and middle ear have distinct embryological origins, with elements from the first and second branchial arches and first pharyngeal pouch [4,8] — and the malformation of the ear and of the ICA may not be directly connected, although a common congenital factor, not identified in our case, could be involved. The ICA irrigates most of the cerebral hemispheres and the orbits and contributes with ramifications to the frontonasal area. In its normal
trajectory [6], the ICA leaves the carotid bulb at the level of the superior edge of the thyroid cartilage of the larynx, crossing its cervical portion without ramifications. The artery penetrates the base of the skull through the carotid canal, in the petrous portion of the temporal bone. After a short vertical segment, passing anterior to the tympanic cavity and the coclea, the ICA becomes more anterior and horizontal in direction of the foramen lacerum. In this petrous portion of the ICA the carotid-tympanic artery and sometimes the pterygoid artery originate. Then, the ICA follows the cavernous portion, surrounded by the cavernous sinus, and passes laterally to the body of the sphenoid performing a prominence in the sphenoidal sinus. In this portion the cavernous, hypophisary and meningeal arteries originate. The ICA passes between the anterior and the medial clinoid apophises of the sphenoid to cross the dura-mater, originating the ophtalmic and anterior choroid arteries in this cerebral portion. In a lateral view, the ICA forms an ‘‘S’’ in the peri and suprasellar area known as carotid siphon. Finally, the ICA forms the circle of Willis, in union with the vertebro-basilar system through the posterior communicating arteries and with the contralateral ICA through the anterior communicating arteries. Situated in the interpeduncular fossa at the base
Fig. 4. CT showing a tumoral mass in the promontory, involving the round window (case 2).
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
Fig. 5. MR-Ischemic lesion in the right lenticular nucleus (case 2).
of the skull, this anastomotic circle originates the anterior, medial and posterior cerebral arteries, often showing anatomical variations. Some fetal vessels may persist into adult life, especially those connecting the carotid and the basilar systems, like the stapedian, primitive-trigeminal, proatlantal, hypoglossal and otic arteries [3]. The ICA may show anatomical variations of trajectory in all its portions, like cervical tortuosity and dehiscence in the middle ear.
2.2. Classification The major congenital abnormalities of the ICA can be classified as agenesis, aplasia and hypoplasia, and they can be uni or bilateral. A 3:1 left
73
side predominance in agenesis of the ICA has been reported. The term agenesis refers to a total absence of the organ (ICA), without any primordium observed. Aplasia is the term for the lack of development of the organ, although some primordium may be seen—in the case of the ICA, a remnant vessel, or some indirect sign of it, like the presence of an ipsilateral carotid canal. In hypoplasia, the organ is present, but has suffered an incomplete embryonic development. Absence of the ICA is refered to as agenesis or aplasia. The blood supply of the affected side or area is partial or totally compensated by another arterial system (vertebrobasilar or contralateral ICA), with enlargement of some normally existing segment or by the presence of an abnormal or even fetal arteries [6,10,12]. Lie [5], in 1968, described six types of collateral circulation observed in these malformations of the ICA (Fig. 7). In type A, at the side of the malformation, an enlarged posterior communicating artery supplies the ipsilateral middle cerebral artery, and the anterior cerebral artery is supplied through the anterior communicating artery. Type B refers to a patent anterior communicating artery that supplies the anterior and middle cerebral arteries. Type C occurs when both internal carotids are absent, and the anterior and medial cerebral arteries are supplied by vessels from the basilar artery. In type D, the cervical and petrous portions of the ICA are absent, and an artery originates from the cavernous portion of the normal ICA. The origin of this vessel is controversial, but it is generally agreed to be an artery—clival, inferior hypophyseal or capsular—that suffered a compensatory hypertrophy and anastomosed with the affected side in the cavernous region. Type E refers to a bilateral hypoplasia of the internal carotid arteries that supply hypotrophied anterior cerebral arteries, and the middle cerebral artery is supplied by enlarged posterior communicating arteries. In type F, the precavernous portion is formed by several arteries constituting a rete mirabile that fills the cavernous portion, with absence of the proximal portions of the ICA. Case 1 is an agenesis, and according to Lie’s description, with a left-right internal carotid shunt through a transellar vessel, it can be classified as
74
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
type D. Case 2 shows hypoplasia of the ICA, with vascular alterations compatible with type B, with the presence of enlarged anterior communicating artery that supplies the right anterior and medial cerebral arteries.
2.3. Clinical features Agenesis, aplasia and hypoplasia may be neurologically asymptomatic for a long time, and they may escape diagnosis until after some neurological manifestation. When present, the symptoms are due to the cerebrovascular insufficiency in a cerebral area, to compression of enlarged vessels or related to the presence of an aneurysm, present in 24–34% of cases. In normally-developed ICA persons, the incidence of aneurysms is estimated to be 2–4% [1,9]. Case 2 showed, in the eighth year of life, focal radiological signs of cerebral insufficiency, whose symptoms in these cases commonly to begin in young adult life [12]. These patients must be followed clinically and radiographically in order to observe the cerebrovascular disorders, especially the development of aneurysms [9]. Diagnosis is often incidental in a radiological examination [10]. CT, MR, angio-MR and arteri-
ography and sonograms are used to manage these cases. The absence or hypoplasia of a carotid canal in a cranial tomography suggests these malformations, as observed in our two cases, and prompts an investigation for intracranial vascular malformations [10]. The angio-MR should be performed together with the conventional MR when possible, and the arteriography should be used for more details or to better visualize small vessels. Interventions in these patients, like cervical, some otological, cranial base (especially near the sella turcica) and cerebral surgeries must be preceded by a vascular study in order to avoid injuries. In Case 2, the compensatory enlarged tympanic inferior artery, in contact with the round window, is the probable cause of the patient’s hearing loss. An exploratory tympanotomy is possible, but interventions in these patients are dangerous and should be restricted to clearly symptomatic cases [11]. The main differential diagnosis in these cases are glomic tumors, cholesteatomas and granulomas, and an arteriography may help in diagnosis. The inferior tympanic artery originates in the ascendent pharyngeal artery, a ramification of the external carotid artery, and anastomoses with the carotidy-tympanic artery in the middle ear.
Fig. 6. Angio-resonancy showing a type B (Lie) collateral blood flow (case 2).
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
75
Fig. 7. Routes of collateral blood flow in cases of congenital hypoplasia or agenesis of internal carotid artery. (A) Normal; (B) six types of collateral flow (after Lie [3,9]).
76
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
Agenesis, aplasia and hypoplasia are isolated pathologies, however they have been described in association with neurofibromatosis type II, congenital polycystic disease of the kidney and Klippel-Trenaunay syndrome [1,2,7]. The association with the external and middle ear malformations, observed in case 1, seems a rare coincidence.
[3] [4] [5] [6]
3. Conclusion [7]
The major congenital malformations of the internal carotid artery — agenesis, aplasia and hypoplasia—are uncommon malformations, but knowledge of them is important because of the clinical and surgical implications. The high incidence of cerebrovascular injuries necessitates a permanent clinical and radiological observation of these patients.
[8]
[9]
[10]
References [11] [1] A.K. Afifi, J.C. Godersky, A. Menezes, W.R. Smoker, W.E. Bell, C.G. Jacoby, Cerebral hemiatrophy, hypoplasia of internal carotid and intracraneal aneurysm, a rare association occuring in an infant, Arch. Neurol. 44 (1987) 232 – 235. [2] S.J. Goldestein, S. Lee, A.B. Young, G.J. Guidry, Aplasia of the cervical internal carotid artery and malformation of
[12]
.
the circle of Willis associated with Klippel-Trenaunay syndrome, J. Neurosurg. 61 (1984) 786 – 789. Gray-Anatomia, Williams and Warwick, Churchill Livingstone, Alhambra Longman, Madrid (1992). J. Langman, Embriologia medica, Nueva Editorial Interamericana, S.A. de C.V. (1976) 212 – 214. T.A. Lie, Congenital anomalies of the carotid arteries, Excerpta Medica, Princeton, NJ, 1968, pp. 35 – 51. R.B. Midkiff, M.W. Boykin, D.R. McFarland, J.A. Bauman, Agenesis of the internal carotid artery with intracavernous anastomosis, Am. J. Neurosci. Res. 16 (1995) 1356 – 1359. Ming-Chang Chen, Hon-Man Liu, Kou-Mou Huang, Agenesis of internal carotid associated with neurofibromatosis type II, Am. J. Neurosci. Res. 61 (1993) 1184 – 1186. K.L. Moore, The developing human, Clinically Oriented Embriology, W.B. Saunders Company, Philadelphia, 1973, pp. 256 – 257. D.J. Quint, R.S. Boulos, T.D. Spera, Congenital absence of the cervical and petrous internal carotid artery with intracavernous anastomosis, Am. J. Neurosci. Res. 10 (1989) 435 – 439. D.J. Quint, R. Silbergleit, W.C. Young, Absence of the carotid canals at skull base, Radiology 182 (1992) 477 – 481. P. Rubinstein, M. Mondain, M. Makeieff, A. Jakies, A. Uziel, B. Guerrier, Traject aberrant de la carotide interne intrape´treuse: a` propos d’un cas, Rev. Laryngol. Otol. Rhinol. 117 (3) (1996) 229 – 232. S. Savastano, G.P. Feltrin, M. Chiesura-Corona, D. Miotta, Cerebral ischemia due to the congenital malformations of brachiocephalic arteries — Case reports, Angiology 43 (1992) 76 – 83.
Case report
Major congenital anomalies of the internal carotid artery: agenesis, aplasia and hypoplasia P. Claro´s *, R. Bandos, I. Gilea, A. Claro´s Jr., A. Capdevila, J. Garcı´a Rodrı´guez, A. Claro´s Clı´nica Claro´s, Los Vergos 31, 08017 Barcelona, Spain Received 6 August 1998; received in revised form 8 January 1999; accepted 9 January 1999
Abstract Agenesis, aplasia and hypoplasia of the internal carotid arteries (ICA) are rare congenital disorders with few descriptions in the otorhinolaryngological literature. We present two cases of major abnormalities of the ICA, one with isolated hypoplasia and another with agenesis associated with ear malformation and facial palsy. We briefly review the normal anatomy and discuss the main aspects of these malformations. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Internal carotid artery abnormalities; Carotid artery displasia; Congenital facial palsy; Ear malformation association
1. Introduction Congenital malformations of the internal carotid artery (ICA) — agenesis, aplasia and hypoplasia—are rare morphological malformations. Tode [7] described for the first time, in 1787, a
* Corresponding author. Fax: +34-93-2803332.
case of agenesis of the ICA, and nearly 100 cases have been reported to date. Most of these are in the radiological and neurological literature, although knowledge of these pathologies is also important for otorhinolaryngologists. In our two cases the initial focus of investigation was the ear, the internal carotid malformation was diagnosed subsequently. Both of them are children, although most of the cases described are in older patients, with frequent symptoms of cerebrovascular disorders.
0165-5876/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 1 6 5 - 5 8 7 6 ( 9 9 ) 0 0 0 1 2 - 9
70
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
1.1. Case 1 A 14-month old boy was referred to our E.N.T. Department due to a malformation of the right
external and middle ear associated with congenital facial palsy (Fig. 1). Clinical examination showed microtia and absence of the external auditive meatus, with a total facial palsy. Behavioural au-
Fig. 1. Frontal aspect of the patient (case 1).
Fig. 2. CT study revealing the absence of the right carotid canal in the skull base (case 1).
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
71
Fig. 3. Angio-resonancy showing a type D (Lie) collateral blood flow (case 1).
diometry showed a 70 dB threshold on the right side, and the brainstem evoked response audiometry revealed a 90 dB threshold, with a V- wave peak-latency of 6.67 ms, compatible with a conductive hearing loss. The left ear showed no alteration. The CT study revealed a malformation of the right external conduct associated with hypoplasia of the middle ear and mastoid, and an anteriorized facial nerve canal. At the base of the skull, the absence of the right carotid canal was observed (Fig. 2), then a complementary examination, with MR and angio-MR imaging, was performed. In these studies, the right ICA was absent, and the angio-MR confirmed the absence of the cervical, petrous and cavernous portion of the right ICA, and a left-right shunt through a transsellar vessel was observed supplying the affected side (Fig. 3). To date, at the age of 2 years, the patient has showed no other alteration, and at the right age he may undergo surgery for the ear malformation.
1.2. Case 2 A 8-year-old boy presented with hypoacusis in the right ear. In the otoscopy, a pulsatile red mass was observed in the hypotympanum, without associated tinnitus. The audiometry revealed a mild conductive hearing loss (15 dB), and the tympanometry test was normal. In the left ear, no alteration was observed. Then, a CT was performed, revealing a mass in the promontory involving the round window (Fig. 4), performing the traject of the inferior tympanic artery. Furthermore the observation of the skull base showed a hypoplasic right carotid canal, suggesting a malformation of the ICA. The hypotesis of a compensatory enlarged inferior tympanic artery was confirmed by arteriography. As a complementary study, the MR showed an ischemic lesion in the right lenticular nucleus, of 2×2 × 1 cm (Fig. 5), and another, smaller, in the ipsilateral caudal nucleus, although the patient presented no neurological symptoms. In angio-MR, the hypo-
72
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
plasy of the ICA was confirmed, and an enlarged anterior communicating artery could be seen, supplying the anterior and the middle cerebral arteries (Fig. 6).
2. Discussion
2.1. Embryology and anatomy The ICA originates in the third aortic arch, and it remains controversial whether the common and external carotidies have the same third aortic arch origin or if they are originated from the aortic sac [8,9]. At the fourth week of gestation the ICA is well defined, and the carotid canal is formed in the skull base after and in depending of the primordial ICA [9,10]. The external and middle ear have distinct embryological origins, with elements from the first and second branchial arches and first pharyngeal pouch [4,8] — and the malformation of the ear and of the ICA may not be directly connected, although a common congenital factor, not identified in our case, could be involved. The ICA irrigates most of the cerebral hemispheres and the orbits and contributes with ramifications to the frontonasal area. In its normal
trajectory [6], the ICA leaves the carotid bulb at the level of the superior edge of the thyroid cartilage of the larynx, crossing its cervical portion without ramifications. The artery penetrates the base of the skull through the carotid canal, in the petrous portion of the temporal bone. After a short vertical segment, passing anterior to the tympanic cavity and the coclea, the ICA becomes more anterior and horizontal in direction of the foramen lacerum. In this petrous portion of the ICA the carotid-tympanic artery and sometimes the pterygoid artery originate. Then, the ICA follows the cavernous portion, surrounded by the cavernous sinus, and passes laterally to the body of the sphenoid performing a prominence in the sphenoidal sinus. In this portion the cavernous, hypophisary and meningeal arteries originate. The ICA passes between the anterior and the medial clinoid apophises of the sphenoid to cross the dura-mater, originating the ophtalmic and anterior choroid arteries in this cerebral portion. In a lateral view, the ICA forms an ‘‘S’’ in the peri and suprasellar area known as carotid siphon. Finally, the ICA forms the circle of Willis, in union with the vertebro-basilar system through the posterior communicating arteries and with the contralateral ICA through the anterior communicating arteries. Situated in the interpeduncular fossa at the base
Fig. 4. CT showing a tumoral mass in the promontory, involving the round window (case 2).
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
Fig. 5. MR-Ischemic lesion in the right lenticular nucleus (case 2).
of the skull, this anastomotic circle originates the anterior, medial and posterior cerebral arteries, often showing anatomical variations. Some fetal vessels may persist into adult life, especially those connecting the carotid and the basilar systems, like the stapedian, primitive-trigeminal, proatlantal, hypoglossal and otic arteries [3]. The ICA may show anatomical variations of trajectory in all its portions, like cervical tortuosity and dehiscence in the middle ear.
2.2. Classification The major congenital abnormalities of the ICA can be classified as agenesis, aplasia and hypoplasia, and they can be uni or bilateral. A 3:1 left
73
side predominance in agenesis of the ICA has been reported. The term agenesis refers to a total absence of the organ (ICA), without any primordium observed. Aplasia is the term for the lack of development of the organ, although some primordium may be seen—in the case of the ICA, a remnant vessel, or some indirect sign of it, like the presence of an ipsilateral carotid canal. In hypoplasia, the organ is present, but has suffered an incomplete embryonic development. Absence of the ICA is refered to as agenesis or aplasia. The blood supply of the affected side or area is partial or totally compensated by another arterial system (vertebrobasilar or contralateral ICA), with enlargement of some normally existing segment or by the presence of an abnormal or even fetal arteries [6,10,12]. Lie [5], in 1968, described six types of collateral circulation observed in these malformations of the ICA (Fig. 7). In type A, at the side of the malformation, an enlarged posterior communicating artery supplies the ipsilateral middle cerebral artery, and the anterior cerebral artery is supplied through the anterior communicating artery. Type B refers to a patent anterior communicating artery that supplies the anterior and middle cerebral arteries. Type C occurs when both internal carotids are absent, and the anterior and medial cerebral arteries are supplied by vessels from the basilar artery. In type D, the cervical and petrous portions of the ICA are absent, and an artery originates from the cavernous portion of the normal ICA. The origin of this vessel is controversial, but it is generally agreed to be an artery—clival, inferior hypophyseal or capsular—that suffered a compensatory hypertrophy and anastomosed with the affected side in the cavernous region. Type E refers to a bilateral hypoplasia of the internal carotid arteries that supply hypotrophied anterior cerebral arteries, and the middle cerebral artery is supplied by enlarged posterior communicating arteries. In type F, the precavernous portion is formed by several arteries constituting a rete mirabile that fills the cavernous portion, with absence of the proximal portions of the ICA. Case 1 is an agenesis, and according to Lie’s description, with a left-right internal carotid shunt through a transellar vessel, it can be classified as
74
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
type D. Case 2 shows hypoplasia of the ICA, with vascular alterations compatible with type B, with the presence of enlarged anterior communicating artery that supplies the right anterior and medial cerebral arteries.
2.3. Clinical features Agenesis, aplasia and hypoplasia may be neurologically asymptomatic for a long time, and they may escape diagnosis until after some neurological manifestation. When present, the symptoms are due to the cerebrovascular insufficiency in a cerebral area, to compression of enlarged vessels or related to the presence of an aneurysm, present in 24–34% of cases. In normally-developed ICA persons, the incidence of aneurysms is estimated to be 2–4% [1,9]. Case 2 showed, in the eighth year of life, focal radiological signs of cerebral insufficiency, whose symptoms in these cases commonly to begin in young adult life [12]. These patients must be followed clinically and radiographically in order to observe the cerebrovascular disorders, especially the development of aneurysms [9]. Diagnosis is often incidental in a radiological examination [10]. CT, MR, angio-MR and arteri-
ography and sonograms are used to manage these cases. The absence or hypoplasia of a carotid canal in a cranial tomography suggests these malformations, as observed in our two cases, and prompts an investigation for intracranial vascular malformations [10]. The angio-MR should be performed together with the conventional MR when possible, and the arteriography should be used for more details or to better visualize small vessels. Interventions in these patients, like cervical, some otological, cranial base (especially near the sella turcica) and cerebral surgeries must be preceded by a vascular study in order to avoid injuries. In Case 2, the compensatory enlarged tympanic inferior artery, in contact with the round window, is the probable cause of the patient’s hearing loss. An exploratory tympanotomy is possible, but interventions in these patients are dangerous and should be restricted to clearly symptomatic cases [11]. The main differential diagnosis in these cases are glomic tumors, cholesteatomas and granulomas, and an arteriography may help in diagnosis. The inferior tympanic artery originates in the ascendent pharyngeal artery, a ramification of the external carotid artery, and anastomoses with the carotidy-tympanic artery in the middle ear.
Fig. 6. Angio-resonancy showing a type B (Lie) collateral blood flow (case 2).
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
75
Fig. 7. Routes of collateral blood flow in cases of congenital hypoplasia or agenesis of internal carotid artery. (A) Normal; (B) six types of collateral flow (after Lie [3,9]).
76
P. Claro´s et al. / Int. J. Pediatr. Otorhinolaryngol. 49 (1999) 69–76
Agenesis, aplasia and hypoplasia are isolated pathologies, however they have been described in association with neurofibromatosis type II, congenital polycystic disease of the kidney and Klippel-Trenaunay syndrome [1,2,7]. The association with the external and middle ear malformations, observed in case 1, seems a rare coincidence.
[3] [4] [5] [6]
3. Conclusion [7]
The major congenital malformations of the internal carotid artery — agenesis, aplasia and hypoplasia—are uncommon malformations, but knowledge of them is important because of the clinical and surgical implications. The high incidence of cerebrovascular injuries necessitates a permanent clinical and radiological observation of these patients.
[8]
[9]
[10]
References [11] [1] A.K. Afifi, J.C. Godersky, A. Menezes, W.R. Smoker, W.E. Bell, C.G. Jacoby, Cerebral hemiatrophy, hypoplasia of internal carotid and intracraneal aneurysm, a rare association occuring in an infant, Arch. Neurol. 44 (1987) 232 – 235. [2] S.J. Goldestein, S. Lee, A.B. Young, G.J. Guidry, Aplasia of the cervical internal carotid artery and malformation of
[12]
.
the circle of Willis associated with Klippel-Trenaunay syndrome, J. Neurosurg. 61 (1984) 786 – 789. Gray-Anatomia, Williams and Warwick, Churchill Livingstone, Alhambra Longman, Madrid (1992). J. Langman, Embriologia medica, Nueva Editorial Interamericana, S.A. de C.V. (1976) 212 – 214. T.A. Lie, Congenital anomalies of the carotid arteries, Excerpta Medica, Princeton, NJ, 1968, pp. 35 – 51. R.B. Midkiff, M.W. Boykin, D.R. McFarland, J.A. Bauman, Agenesis of the internal carotid artery with intracavernous anastomosis, Am. J. Neurosci. Res. 16 (1995) 1356 – 1359. Ming-Chang Chen, Hon-Man Liu, Kou-Mou Huang, Agenesis of internal carotid associated with neurofibromatosis type II, Am. J. Neurosci. Res. 61 (1993) 1184 – 1186. K.L. Moore, The developing human, Clinically Oriented Embriology, W.B. Saunders Company, Philadelphia, 1973, pp. 256 – 257. D.J. Quint, R.S. Boulos, T.D. Spera, Congenital absence of the cervical and petrous internal carotid artery with intracavernous anastomosis, Am. J. Neurosci. Res. 10 (1989) 435 – 439. D.J. Quint, R. Silbergleit, W.C. Young, Absence of the carotid canals at skull base, Radiology 182 (1992) 477 – 481. P. Rubinstein, M. Mondain, M. Makeieff, A. Jakies, A. Uziel, B. Guerrier, Traject aberrant de la carotide interne intrape´treuse: a` propos d’un cas, Rev. Laryngol. Otol. Rhinol. 117 (3) (1996) 229 – 232. S. Savastano, G.P. Feltrin, M. Chiesura-Corona, D. Miotta, Cerebral ischemia due to the congenital malformations of brachiocephalic arteries — Case reports, Angiology 43 (1992) 76 – 83.