Rete Mirabile in Humans. Case Report

Transcription

1 Rete Mirabile in Humans Case Report Jun KARASAWA, Hajime TOUHO, Hideyuki OHNISHI, and Masahiko KAWAGUCHI* Departments of Neurosurgery and *Anesthesiology, Osaka Neurological Institute, Toyonaka, Osaka Abstract Carotid rete mirabile is a physiological vascular network between the external carotid and internal carotid systems present in some vertebrate species, but rarely observed in humans. We describe a 17- year-old girl with rete mirabile who presented with subarachnoid hemorrhage. Angiography disclosed the bilateral internal carotid arteries (ICAs) ended at the cavernous portion, and abnormal arterial net works visualized via the ICAs and the external carotid arteries in the paracavernous region. The distal ICAs were visualized via the abnormal arterial networks. After 18 years of follow-up she is leading a normal life without neurological problems. Rete mirabile in humans may present with hemorrhage or ischemic symptoms, but the prognosis appears to be good. Key words: arterial rete mirabile, abnormalities, carotid artery Received September 20, 1995; Accepted November 12, 1996 Introduction Rete mirabile, a physiological vascular network be tween the external carotid and internal carotid sys tems, was first described by Herophilus of Alexan dria ( B.C.).3) Rete mirabile occurs in some vertebrates including ungulates and cats.") The in tracranial internal carotid arteries (ICAs) are sup plied via the arterial network (rete mirabile) at the base of the skull mainly through the internal maxil lary artery, a branch of the external carotid artery (ECA). The proximal ICA is usually hypoplastic or undeveloped, whereas the ECA is large. Carotid rete mirabile is a very rare pathological condition in hu mans, with only 11 reported cases. 1,1,1-8,10-13,15,16) Rete mirabile may manifest as hemorrhage or ischemic cerebrovascular disorders 8) but the prognosis is unknown. We report a patient with rete mirabile manifesting as subarachnoid hemorrhage (SAH). Case Report A 17-year-old girl suffered sudden onset of severe headache, nausea, and vomiting. Lumbar puncture demonstrated bloody cerebrospinal fluid at a local hospital. She had suffered headache from 1965 to She was referred to our department on Decem ber 14, On admission, she was somnolent with severe nuchal rigidity and exaggerated patellar tendon reflex. No motor dysfunction, speech disturbance, or cranial nerve dysfunction was observed. Right internal carotid angiography (Fig. 1) demon strated that the right ICA was slightly small and end ed at the cavernous portion (C4), where an abnormal network was noted. Portions distal to the anterior knee (C3) of the right ICA were supplied via the ab normal network. The middle cerebral artery (MCA) was normal. The anterior cerebral artery (ACA) and posterior cerebral artery (PCA) were not visualized. Right external carotid angiography (Fig. 2) demon strated that the right ECA was larger than the right ICA. The distal portion of the ipsilateral ICA received blood supply via the deep temporal artery, the internal maxillary artery, and the middle menin geal artery, and as a result the MCA was well visual ized. The MCA and ophthalmic artery were both bet ter visualized by right external than right internal carotid angiography. Left internal carotid an giography (Fig. 3) demonstrated that the left ICA end ed at the C4i where the abnormal network was noted. The C3 portion of the left ICA was supplied via the

2 Fig. 1 Right internal carotid angiograms, an teroposterior (left) and lateral (right) views, showing the internal carotid artery (ICA) ended at the cavernous segment (ar rowhead), and the distal portion of the right ICA received blood supply via the abnor mal network. abnormal vascular network. The left ophthalmic and posterior communicating arteries were not visual ized. The ACAs were visualized bilaterally via the left ICA. Left external carotid angiography (Fig. 4) Fig. 2 Right external carotid angiograms, an teroposterior (left) and lateral (right) views, showing the right internal carotid artery distal to the cavernous segment was filled via the abnormal network originating from the external carotid artery. arrow: internal maxillary artery, arrowhead: middle me ningeal artery, double arrow: deep temporal artery, thick arrow: ophthalmic artery, curv ed arrow: accessory meningeal artery. demonstrated that the large ophthalmic artery and the C3 portion of the left ICA were supplied via a Fig. 3 Left internal carotid angiograms, anteroposterior (left), lateral (center), and axial (right) views, showing the internal carotid artery (ICA) ended at the cavernous segment (arrowhead), and the distal portion of the left ICA was visualized via the well-developed abnormal net work.

3 Fig. 4 Left external carotid angiograms, anteroposterior (left), lateral (center), and axial (right) views, showing the internal carotid artery distal to the cavernous segment was filled via the abnormal network originating from the external carotid artery. arrow: internal maxillary artery, arrowhead: middle meningeal artery, thick arrow: ophthalmic artery, curved arrow: ac cessory meningeal artery. Fig. 5 Left vertebral angiograms, anteroposterior (left) and lateral (right) views, showing the first segment of the left posterior cerebral ar tery (PCA) was not visualized, and the distal portion of the left PCA received blood sup ply via the thalamoperforating arteries. arrow: posterior communicating artery. Fig. 6 Scheme of angiographic findings. ACA: an terior cerebral artery, BA: basilar artery, ECA: external carotid artery, ICA: internal carotid artery, IMA: internal maxillary ar tery, MCA: middle cerebral artery, MMA: middle meningeal artery, Opt.: ophthalmic artery, PCom: posterior communicating ar tery, STA: superficial temporal artery. number of abnormal arteries through an abnormally large internal maxillary artery and middle menin geal artery. The left ICA was better visualized by left external than left internal carotid angiography. Left vertebral angiography (Fig. 5) showed that the left PCA was not visualized in the peduncular segment, and portions distal to the ambient segment of the left PCA were supplied via the abnormal arterial net work. The abnormal arterial network was fed by the anterior and posterior thalamoperforating arteries.

4 The left ICA and left MCA were normogradely visualized via the left posterior communicating ar tery, which was supplied via the left PCA. A portion of the right ACA was retrogradely visualized via the posterior pericallosal artery. Right vertebral an giography showed the right vertebral artery was nor mal. The bilateral ICAs ended at the C4 portions, and an abnormal arterial network (carotid rete mirabile) was visualized via the ICA and the ECA in the paracavernous region. C3 portions were visualized via the abnormal arterial network. These findings were similar bilaterally. Cerebral angiography de tected no aneurysm or arteriovenous malformation (Fig. 6). Four days after admission, she developed mild left hemiparesis which improved within 4 days. She was alert without neurological deficits at discharge on February 2, In December 1995, after a 18-year follow-up period, she was a mother with a child and leading a normal life without neurological symp toms. Table 1 Rete mirabile in humans Discussion Previous cases of rete mirabile in humans are sum marized in Table 1. In most cases of carotid rete mirabile, the ICA ended in the ganglionic portion (C5), in which the rete mirabile was present, and por tions distal to the supraclinoid portion of the ICA were supplied via the rete mirabile. The abnormal portion of the ICA was 0.5 to 1 cm long, and the rete mirabile was located between the base of the skull and dura mater. The circle of Willis was normal. The ascending pharyngeal artery and occipital artery are occasionally associated with rete mirabile.10) In our case, the bilateral ICAs ended at C4, and the distal portions were supplied via collateral circulation from the carotid rete mirabile. These anastomotic channels were supplied via the ICAs and via the in ternal maxillary artery of the ECA. Five patients with rete mirabile, including ours, presented with SAH, and two patients presented with episodes of ischemia. Two of the five patients with SAH harbored aneurysms, and the cause of SAH was unknown in three patients. In our case, an giography detected no aneurysm. The cause of SAH was considered to be related to the abnormal vascu lar networks. The left hemiparesis noted 4 days after admission was thought to be due to vasospasm. The prognosis for patients with rete mirabile appears to be good, although one patient with rete mirabile died as a result of severe SAW) No recurrence of SAH or ischemic episodes was noted in the other patients. Our patient is presently leading a normal life without neurological problems 17 years after the diagnosis of rete mirabile. Carotid rete mirabile in lower mammals is thought to provide heat exchange to prevent overheating of the brain,') and protection of the brain by regulation of the pressure and flow of the cerebral circula tion.4,14) These effects are of minor importance in hu mans. Rete mirabile does not occur in any stage of normal human development,) so is thought to be an anomalous atavistic development. However, the ex act pathogenesis and clinical significance of rete mirabile in humans remain unknown. The five most recent patients were all Japanese. Moyamoya dis ease, a cerebrovascular occlusive disease, is also prevalent in the Japanese. References 1) Araki Y, Imai S, Saitoh A, Ito T, Shimizu K, Yamada H: [A case of carotid rete mirabile associated with pseudoxanthoma elasticum: A case report]. No To Shinkei 38: , 1986 (Jpn) 2) Danzinger J, Bloch S, Hefer AG: Bilateral rete carot ids in man. A case report. S Afr Med j 46: , ) de Gutierrez-Mahoney CG, Schechter MM: The myth of rete mirabile in man. Neuroradiology 4: , ) Edelman NH, Epstein P, Cherniack NS, Fishman AP:

5 Control of cerebral blood flow in the goat: Role of the carotid rete. Am J Physiol 223: , ) Fields WS, Bruetman ME, Weide J: Collateral circula tion of the brain. Monogr Surg Sci 2: , ) Fuwa I: A pediatric case of carotid rete mirabile. Case report. Stroke 25: , ) Hawkins TD, Scott WC: Bilateral rete carotidis in men. Clin Radio] 18: , ) Itoyama Y, Kitano I, Ushio Y: Carotid and vertebral rete mirabile in man. Case report. Neurol Med Chir (Tokyo)33: ,1993 9) Jessen C, Pongrats H: Air humidity and carotid rete function in thermoregulation of the goat. J Physiol (Lond) 292: , ) Koo AH, Newton TH: Pseudoxanthoma elasticum as sociated with carotid rete mirabile. Case report. AJR Am J Roentgenol 116: 16-22, ) Lie TA: Congenital Anomalies of the Carotid Arteries. Amsterdam, Excerpta Medica, 1986, pp ) Minagi H, Newton TH: Carotid rete mirabile in man. Radiology 86: , ) Morimoto A, Hashi K, Tanabe S, Ando S, Imaizumi T, Oota K, Takigami M: [Bilateral hypoplasia of the in ternal carotid artery associated with carotid rete mirabile]. Rinsho Hoshasen 32: , 1987 (Jpn) 14) Nagel EL, Moragane PJ, McFarland WL, Galliano PE: Rete mirabile of dolphin: Its pressure-damping effect on cerebral circulation. Science 161: , ) Rios-Montenegro EN, Behrens MM, Hoyt WF: Pseu doxanthoma elasticum. Arch Neurol 26: , ) Rockett JF, Johnson TH: Bilateral rete mirabile in tracranial (vascular) anastomosis in man: A report. Radiology 90: 46-48, 1968 Address reprint requests to: J. Karasawa, M.D., Depart ment of Neurosurgery, Osaka Neurological Institute, Shonai Takara-machi, Toyonaka, Osaka 561, Japan/