THE NORMAL MIDDLE CEREBRAL ARTERY AXIS* By JOHN P. JIMENEZ, M.D., and JOHN A. GOREE, M.D. DURHAM, NORTH CAROLINA

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1 SEPTEMBER, 197 THE NORMAL MDDLE CEREBRAL ARTERY AXS* By JOHN P. JMENEZ, M.D., and JOHN A. GOREE, M.D. DURHAM, NORTH CAROLNA Downloaded from by on 12/02/17 from P address Copyright ARRS. For personal use only; all rights reserved T HE significance ofdisplacement of the major middle cerebral artery trunks in the angiographic localization of expanding intracranial lesions has been appreciated since the initial studies of Moniz,3 who considered the groupe sylvien to represent the arterial axis of the brain. Gross elevation of these vessels by both intnacerebral and extracerebral masses in the middle fossa is easily recognized. However, a minor upward displacement of this arterial complex may be more difficult to assess, particularly in infants and children. Methods for measuring the normal and pathologic locations of the middle cerebral artery trunks from the lateral carotid anteniogram have been described by Tavenas and Poser,5 and Woninger and Gernez. The purpose of this paper is to present a simple method for determining the normal middle cerebral artery axis as visualized on the lateral projection of the carotid arteniognam. The accuracy of this method is to be evaluated in both the normal child and adult, and also in a series of verified mass lesions in the middle fossa. MATERALS AND METHODS From the cerebral angiographic material in the teaching file of the Department of Radiology at Duke University Medical Center, 500 normal lateral carotid arteniograms in adult patients were selected as representing technically satisfactory examinations. Particular attention was paid to rotation of the skull. Any case with rotation of the mid-sagittal plane amounting to more than several millimeters, defined by measuring the degree of incomplete superimposition of both the orbital plates and the petrous pyramids (Fig. i, A and B) was discarded, since this limitation will obviously alter the position of the middle cerebral artery trunks. A second group of 75 normal carotid arteniograms was similarly selected from the pediatric material for FG.. Normal adult carotid arteriogram. (A) Exact superimposition of orbital plates and petrous pyramids. ( B) Pseudo-elevation of middle cerebral artery axis from rotation of skull. Same case as in A. B From the Department of Radiology, Duke University Medical Center, Durham, North Carolina.

2 VOL. 101, No. The Normal Middle Cerebral Artery Axis 9 Downloaded from by on 12/02/17 from P address Copyright ARRS. For personal use only; all rights reserved P 0 FG. 2. (A) Diagram of the method of determining the middle cerebral artery axis. (B) Normal middle cerebral artery axis in a year old child. (C) Normal middle cerebral artery axis in an adult. study, the patients ranging in age from months to i years. A third group was selected, consisting of ioo cases of verified expanding lesions in the middle fossa. As in the normal cases, only anteniograms with very little or no rotation were included. All of the patients in the pathologic group were adults. Two points on the inner table of the skull were utilized, namely, the inner table margin of the bregma (A) and the internal occipital protuberance (B) (Fig. 2, 4, B and C). A line was drawn to connect these two points of reference and the mid-point (C) was considered to be the posterior limit of the middle cerebral artery axis. The limbus sphenoidalis (D) was selected as an additional landmark. This structure is reasonably well seen on the lateral carotid arteniogram, and as Holman points out, the pituitary fossa is in a relatively lower position with respect to the level of the planum sphenoidale in the newborn than it is in older people (Fig. 3, z and B). Therefore, bone landmarks more closely related to the sella turcica proper, such as the tubenculum sellae and the anterior clinoid processes, will tend to give a lower estimate of the middle cerebral artery axis than if the limbus sphenoidalis is utilized, particularly in infants and children. Occasionally, the exact point of the limbus was difficult to

3 90 J ohn P. Jimenez and John A. Goree SEPTEMBER, ,. 5 S 5_S Downloaded from by on 12/02/17 from P address Copyright ARRS. For personal use only; all rights reserved FG. 3. (A) Sella turcica in a normal infant. (B) Sella turcica in a normal adult. The upper arrow points to the limbus sphenoidalis and the lower arrow is at the tuberculum sellae. define. n such a case, the most posterior point visible along the planum sphenoidale was considered to be point D. The estimated middle cerebral artery axis, considered here as merely the trend of direction and location of the major arterial trunks of the middle cerebral artery, was then drawn directly on each roentgenogram. The main trunks of the middle cerebral artery have been arbitrarily defined by Ring4 as those major vessels passing without interruption through the middle third of the sylvian fissure. A line (CD) was then constructed (Fig. 2, ii, B and C) and the distance in millimeters between the line CD and the estimated axis, measured at the mid-point E, was recorded in each case. When the middle cerebral artery trunks were found to be clearly bowed upward by an expanding lesion, it was obviously impossible to define a rectilinear axis. n such cases, the measurement to the major middle cerebral artery trunks opposite point E was made without a middle cerebral artery axis estim ation. RESULTS The measurements in the normal adult material are listed in Table i. The figures for normal infants and children are shown in Table and the data for the group of verified expanding lesions in the middle fossa are listed in Table. Table V compares the average mean and the range between these 3 groups. The range of elevation of the middle THE MDDLE CEREBRAL ARTERY AXS N 500 NORMAL ADULT CAROTD ARTEROGRAMS mm. Above Line CD No. of Cases Per Cent LineCD i ! mm. Below Line CD

4 VOL. 101, No. The Normal Middle Cerebral Artery Axis 9 THE MDDLE CEREBRAL ARTERY AXS N 75 NORMAL CAROTD ARTEROGRAMS N CHLDREN THE MDDLE CEREBRAL ARTERY AXS in 100 EXPANDNG LESONS N THE MDDLE FOSSA Downloaded from by on 12/02/17 from P address Copyright ARRS. For personal use only; all rights reserved mm. Above Line CD No. of Cases Per Cent o.o cerebral artery axis in the ioo pathologic cases was to 41 mm. above line CD, with a single case having as little as mm. elevation and 95 cases measuring 10 mm. or more above this line. On the contrary, only a single case in the normal adult series was found to have a middle cerebral artery axis of more than mm. above line CD. Since there is no surgical or autopsy evidence for the presence of a disease process in the middle fossa of this patient, her clinical findings are briefly reviewed. J.B.M., DUMC No. F A 22 year old white female was involved in an automobile accident 2 days before admission to this hospital. She was thrown from the car and rendered unconscious. Upon admission to her local hospital, she was found to have lacerations of the right scalp, an alternating state of consciousness and right occipital and temporal linear skull fractures. She became less responsive over the following week and examination Children Adults Pathologic mm. Above Line CD No. of Cases Per Cent V 4 mm.-5 mm upon admission to this hospital revealed a moderately obtunded state of consciousness, hyperactive reflexes and a left extensor plantar response. A right carotid arteriogram was performed 2 days later (Fig. 4) and was interpreted as normal. The patient subsequently improved, her neurologic status reverted to normal and she was discharged with the diagnosis of cerebral contusion. Comment. The measurements made in this case are shown in Figure 4. There is an elevation of the middle cerebral artery axis of 12 mm. above line CD. t is assumed that this finding represents some swelling of the right temporal lobe, probably from contusion, although it would be impossible to exclude hemorrhage. n the Too verified pathologic cases, minor elevations of the middle cerebral anteny axis (io mm. or less), were found to be due to hemorrhage in 3 cases. The other small elevations were seen in 2 cases of temporal lobe astrocytoma, one case of THE RELATONSHP BETWEEN LNE CD AND THE MDDLE CEREBRAL ARTERY AXS Average Distance Above Line CD (mm.) No. of Cases Range Above and Below Line CD (mm.) o-io above below- above* -4! above 2 * Excluding one case 12 mm. above (see Fig. 4).

5 92 J ohn P. Jimenez and John A. Gonee SEPTEMBER, 97 Downloaded from by on 12/02/17 from P address Copyright ARRS. For personal use only; all rights reserved FG. 4. Elevation of the middle cerebral artery axis in a case of probable contusion of the temporal lobe. glioblastoma multiforme of the temporal lobe, and a single instance of (ptenional) meningioma. Elevation of the middle cerebral artery axis was found to be as little as mm. in a single case of intracerebral hematoma and 7 mm. in one instance of glioblastoma multiforme. The 75 pediatric measurements produced a maximum normal distance of the middle cerebral artery axis above line CD of io mm. in 3 cases, with no particular differences noted in the various age groups. DSCUSSON One of the fufidamental considerations in attempting to establish a linear measurement for the normal middle cerebral artery axis is that most measurements in diagnostic roentgenology are sharply limited in value and the absolute demarcation between normal and pathologic is difficult to define. Any measurement must be utilized in context with the total roentgenognaphic picture and an individual measurement that just exceeds the upper limits of normal in the face of an otherwise negative examination must be viewed with strong reservations. A widely utilized measurement of the middle cerebral artery axis is the clino- parietal line described by Taveras and Poser.5 This measurement requires the antenor clinoid process and the lambda (or internal occipital protuberance) for reference points. These authors have stated that occasionally the line is just above the lowest major branch in the adult. n children, the major middle cerebral branches are always above the clino-panietal line. t is v noted that in i of the 75 children listed in Table,, the middle cerebral artery axis coincided exactly with line CD. Taveras and Poser5 also mentioned that it may be noted that in younger children the distance from the clino-panietal line to the lowest major branch of the middle cerebral antery... is greater than in older children. We have found no such change in the middle cerebral artery axis with advancing age (Fig. ) other than the gross comparison between the pediatric and adult series. Woninger and Gennez attempted to establish a normal middle cerebral artery axis by measuring the angle between the middle cerebral artery trunks on the lateral arteniogram and a line drawn from the internal occipital protuberance to the center of the sella turcica. Since it is often the case that an expanding process elevates the middle cerebral artery trunks in a fashion parallel to the original course of these vessels, this measurement has limited value. The general appearance of the middle cerebral artery trunks, the status of the antenor choroidal, posterior communicating 0 U , l4B Ag. n Yars FG. 5. Relation of the middle cerebral artery axis to line CD in 75 normal infants and children.

6 VOL. O, No. The Normal Middle Cerebral Artery Axis 93 Downloaded from by on 12/02/17 from P address Copyright ARRS. For personal use only; all rights reserved and posterior cerebral arteries and the basilan vein, midline dislocations, the appearance of the middle cerebral artery in the frontal plane of anteniography, and the presence and type of tumor neovasculanity are all important in the angiognaphic diagnosis of middle fossa expanding lesions. n addition, there is a certain degree of observer variation in estimating the middle cerebral artery axis from the lateral noentgenogram. Nevertheless, it is believed that the combination of this simple linear measurement, together with the insistence upon an accurately positioned patient during the examination, will improve the evaluation of the middle cerebral artery axis in the problem case. SUMMARY A simple method for the evaluation of the normal and pathologic middle cerebral artery axis as determined from the lateral carotid arteniogram is presented. These measurements have been applied to both adults and children and have been found to be of assistance in cerebral angiographic interpretation. John P. Jimenez, M.D. Department of Radiology Duke University Medical Center Durham, North Carolina 2770 RE FERENCES. HOLMAN, C. B. Roentgenologic manifestations of glioma of optic nerve and chiasm. Ars. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., 1959, 2, LUSTED, L. B., and KEATS, T. E. Atlas of Roentgenographic Measurement. Year Book Publishers, nc., Chicago, 1959, pp MoNz, E. L Angiographic C#{233}r#{233}brale. Masson et Cie, Paris, RNG, B. A. Middle cerebral artery: anatomical and radiographic study. Acta radio!., 192, 57, TAvERAS, J. M., and POSER, C. M. Roentgenologic aspects of cerebral angiography in children. AM. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., 1959, 2, WORNGER, E., and GERNEZ, A. L art#{233}riogramme c#{233}r#{233}bral; essai de definition des frontiers de l art#{233}riogramme carotidien normal et de ses variations: analyse de 100 cas. Presse med., 194,5, 1-2.