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Cranial Bruit—Its Significance
Cranial Bruit-Its Significance JAMES L. POPPEN
NOISES in the head are frequently mentioned by patients as their major complaint. Since the noise is of great annoyance to many patients, considerable attention should be given to its etiology. The various conditions that must be kept in mind which can cause a bruit are: arteriovenous fistula (Fig. 243), vascular malformations6 (Fig. 244), a brain tumor which compresses one of the larger arteries (Fig. 245), hemangioblastomatous meningiomas, intrinsic or intracranial arterial changes, such as arteriosclerotic or atheromatous plaques (Fig. 246), aneurysm 6 that has ruptured into a venous sinus, glomus jugularis and carotid body tumors, murmurs transmitted to the larger vessels in the head through the carotid system in hypertensive-arteriosclerotic patients, coarctation of the aorta, highly vascular thyroid glands, scalp angiomas (Fig. 247), traumatic arteriovenous fistulas and Paget's disease (Fig. 248). Other causes of noises in the head which may be confused with a bruit or murmur are rhythmic contractions of the pharyngeal muscles in hysterical patients. It is quite obvious that a clicking or crunching noise, such as in chronic myositis of the neck muscles or the temporomandibular joints, or noises occurring during swallowing due to opening and closing of the eustachian tube are not significant except that they should be mentioned as possible causes of noises in the head. Aeroceles, sinusitis when both air and fluid are present, fluid in the external auditory canal, and inflammatory changes in the eustachian tube are possible sources for noises in the head. Cranial bruit or murmur may be subjective, objective or both. However, in either case it is always synchronous with the heart beat. It must not be confused with the pulse beat that may be heard when the head is pressed against a pillow or firm object. Subjective bruit may be suspected and can be verified by asking the patient to beat time by hand with the noise of which he complains. The examiner, with his finger on the radial pulse, can readily determine whether the noise is synchronous with the pulse. The patient usually localizes the noise to one or the other side of the head. In some instances, however, it cannot be localized. Occlusion of either carotid artery in the neck by digital compression may obliterate the noise or alter its charac-
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James L. Poppen Poppen James L.
Fig. fistula. Fig. 243. 243. Arteriogram Arteriogram demonstrating demonstrating arteriovenous arteriovenous (carotid-cavernous) (carotid-cavernous) fistula.
Fig. by arteriography. arteriography. and lateral lateral views views of of vascular vascular malformation malformation by Fig.244. 244. Anteroposterior Anteroposterior and
ter. If it does, one can be reasonably certain that a bruit is present even though it cannot be heard by the examiner with the naked ear, the stethoscope or reinforced amplication as by the stethetron. Unfortunately, one cannot accurately occlude the vertebral artery in all patients so that it is impossible positively to exclude the vertebral system.
Cranial Bruit-Its Significance
883
Fig. 245. Arteriogram demonstrating vascular meningioma in left pterionaCregion.
Fig. 246. Arteriogram demonstrating a local area of constriction in the occipital artery interpreted to be due to an atheromatous plaque in the vessel wall.
The examiner should be certain to auscultate the head in various positions, sitting, prone and with the patient lying down on either side. Many times a murmur cannot be heard unless a stethoscope is placed beneath the head with the patient lying on the stethoscope.
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James L. Poppen James L. Poppen
Fig. 247. Arteriogram of angioma of scalp demonstrating artery and faint outline of vein (superficial temporal vessels). Fig. 247. Arteriogram of angioma of scalp demonstrating artery and faint outline of vein (superficial temporal vessels).
Fig. 248. Paget's disease showing narrowing of carotid canal in petrous bone. Fig. 248. Paget's disease showing narrowing of carotid canal in petrous bone.
Cranial Bruit-Its Significance
885
Objective bruit may at times be elicited in patients who are not aware of a bruit. It is important that the surroundings are quiet while auscultating. The physician must learn to ignore the various noises that, can be heard, such as crackling of hair, respirations, deglutition, and so forth. Bruits may be harsh, soft, whistling, rumbling, churning, or a machinery murmur. The character of the bruit may change during respiration, or occlusion of one or the other carotid artery. For instance, if the bruit is more audible over one side of the skull, occlusion of the ipsilateral carotid may change the pitch of the bruit or obliterate it. If the first condition is present it may mean that the artery is not completely obliterated or that coarse collateral circulation is taking place or that the vertebral system is involved. If the opposite or contralateral artery is occluded, the- noise is usually altered by its. becoming louder. In patients with a slightly irritable carotid sinus a slowing or loss of intensity of the bruit may readily be noted. Normal blood flow does not give rise to a bruit. Vibration arising under certain conditions and noted as rhythmic noises may theoretically be caused either in the blood stream or in the blood vessel wall. Most bruits have their origin in the vibrations of the blood itself. A change in the radius of the vessel and the velocity of the blood stream is important in producing a murmur. Increase in the size of the vessels in arterial aneurysm may be a cause. The production of a high velocity is significant in other vessel disorders. The rate of speed may be altered by changes in blood pressure or in the caliber of the vessels since velocity is directly proportionate to pressure and inversely proportionate to the vessel size. It is for that reason that a murmur may become audible when the pulse pressure is increased by exercise or stimulant. It must be emphasized that a change in the blood vessel size must be abrupt in order to produce vibrations. Gradual convergence or divergence of the vessel wall tends to overcome the vibrations in the blood stream itself. A murmur heard directly over a narrowed segment of an artery is loud and of long duration. Bruits caused by arteriovenous fistulas are usually continuous, socalled to-and-fro murmurs, since the changes in frequency and amplitude during the systolic and diastolic phases may be markedly pronounced. The to-and-fro murmur may be changed to a systolic murmur if the large vein which drains the artery is occluded. This is true only if the fistula is unilateral as in the carotid-cavernous sinus fistula. In a few instances fistulas may be bilateral. The size of the opening between the artery and the vein or sinus greatly alters the character of the noise. This is also true if the lumen of an artery is abruptly constricted in varying degrees. If the constriction by an arteriosclerotic plaque, for instance, is at a low level, bruit occurs in the late diastole. As the constriction increases, the noise is best heard in systole and becomes louder. Gupta and Wiggers4 found in experimental
James L. Poppen
886
coarctation that aortic murmurs were produced when 60 per cent of the lumen was constricted. The murmurs were loudest when 73 per cent of the lumen was constricted and no longer audible at 78 per cent. Edwards and Levine 2, 3 have studied extensively murmurs produced by diseases that cause change in the peripheral arteries. They found that a considerable degree of accuracy can be obtained in locating the site of constriction or fistula. They stated that a murmur is often heard over a wide area, but is most intense directly over the fistula. Unfortunately, because of the sounding board effect of the skull, one cannot find, in most instances, the exact site of the condition that causes the bruit although there is no question but that the noise is usually greatest in the immediate vicinity of the disease. Since many of these intracranial conditions, however, are situated in the midline, it can easily be understood why the noise can be heard well bilaterally. In Paget's disease I believe the bruit is caused by the narrowing of the cranial foramina at the base, constricting the lumen of the vessels. I have not heard a bruit or murmur in a patient with Paget's disease unless there was marked involvement of the base of the skull. Adson1 emphasized the fact that atheromatous plaques in the subclavian artery caused by constant irritation of a cervical rib or band compressing the artery could cause murmurs. REFERENCES 1. Adson, A. W.: Surgical treatment for symptoms produced by cervical ribs and scalenus anticus muscle. Surg., Gynec. & Obst. 85: 687-700 (Dec.) 1947. 2. Edwards, E. A. and Levine, H. D.: Peripheral vascular murmurs; Mechanism of production and diagnostic significance. A.M.A. Arch. Int. Med. 90: 284-300 (Sept.) 1952. 3. Edwards, E. A. and Levine, H. D.: The murmur of peripheral arteriovenous fistula. New England J. Med. 247: 502-505 (Oct. 2) 1952. 4. Gupta, T. C. and Wiggers, C. J.: Basic hemodynamic changes produced by aortic coarctation of different degrees. Circulation 3: 17-31 (Jan.) 1951. 5. Hoover, W. B.: Left carotid jugular arteriovenous communication. S. CLIN. NORTH AMERICA 9: 1453-1457 (Dec.) 1929. 6. Richardson, C. and Kofman, 0.: Cranial bruit with intracranial saccular aneurysms Tr. Am. Neurol. A. 76: 151-154, 1951.
NOISES in the head are frequently mentioned by patients as their major complaint. Since the noise is of great annoyance to many patients, considerable attention should be given to its etiology. The various conditions that must be kept in mind which can cause a bruit are: arteriovenous fistula (Fig. 243), vascular malformations6 (Fig. 244), a brain tumor which compresses one of the larger arteries (Fig. 245), hemangioblastomatous meningiomas, intrinsic or intracranial arterial changes, such as arteriosclerotic or atheromatous plaques (Fig. 246), aneurysm 6 that has ruptured into a venous sinus, glomus jugularis and carotid body tumors, murmurs transmitted to the larger vessels in the head through the carotid system in hypertensive-arteriosclerotic patients, coarctation of the aorta, highly vascular thyroid glands, scalp angiomas (Fig. 247), traumatic arteriovenous fistulas and Paget's disease (Fig. 248). Other causes of noises in the head which may be confused with a bruit or murmur are rhythmic contractions of the pharyngeal muscles in hysterical patients. It is quite obvious that a clicking or crunching noise, such as in chronic myositis of the neck muscles or the temporomandibular joints, or noises occurring during swallowing due to opening and closing of the eustachian tube are not significant except that they should be mentioned as possible causes of noises in the head. Aeroceles, sinusitis when both air and fluid are present, fluid in the external auditory canal, and inflammatory changes in the eustachian tube are possible sources for noises in the head. Cranial bruit or murmur may be subjective, objective or both. However, in either case it is always synchronous with the heart beat. It must not be confused with the pulse beat that may be heard when the head is pressed against a pillow or firm object. Subjective bruit may be suspected and can be verified by asking the patient to beat time by hand with the noise of which he complains. The examiner, with his finger on the radial pulse, can readily determine whether the noise is synchronous with the pulse. The patient usually localizes the noise to one or the other side of the head. In some instances, however, it cannot be localized. Occlusion of either carotid artery in the neck by digital compression may obliterate the noise or alter its charac-
881
882 882
James L. Poppen Poppen James L.
Fig. fistula. Fig. 243. 243. Arteriogram Arteriogram demonstrating demonstrating arteriovenous arteriovenous (carotid-cavernous) (carotid-cavernous) fistula.
Fig. by arteriography. arteriography. and lateral lateral views views of of vascular vascular malformation malformation by Fig.244. 244. Anteroposterior Anteroposterior and
ter. If it does, one can be reasonably certain that a bruit is present even though it cannot be heard by the examiner with the naked ear, the stethoscope or reinforced amplication as by the stethetron. Unfortunately, one cannot accurately occlude the vertebral artery in all patients so that it is impossible positively to exclude the vertebral system.
Cranial Bruit-Its Significance
883
Fig. 245. Arteriogram demonstrating vascular meningioma in left pterionaCregion.
Fig. 246. Arteriogram demonstrating a local area of constriction in the occipital artery interpreted to be due to an atheromatous plaque in the vessel wall.
The examiner should be certain to auscultate the head in various positions, sitting, prone and with the patient lying down on either side. Many times a murmur cannot be heard unless a stethoscope is placed beneath the head with the patient lying on the stethoscope.
884 884
James L. Poppen James L. Poppen
Fig. 247. Arteriogram of angioma of scalp demonstrating artery and faint outline of vein (superficial temporal vessels). Fig. 247. Arteriogram of angioma of scalp demonstrating artery and faint outline of vein (superficial temporal vessels).
Fig. 248. Paget's disease showing narrowing of carotid canal in petrous bone. Fig. 248. Paget's disease showing narrowing of carotid canal in petrous bone.
Cranial Bruit-Its Significance
885
Objective bruit may at times be elicited in patients who are not aware of a bruit. It is important that the surroundings are quiet while auscultating. The physician must learn to ignore the various noises that, can be heard, such as crackling of hair, respirations, deglutition, and so forth. Bruits may be harsh, soft, whistling, rumbling, churning, or a machinery murmur. The character of the bruit may change during respiration, or occlusion of one or the other carotid artery. For instance, if the bruit is more audible over one side of the skull, occlusion of the ipsilateral carotid may change the pitch of the bruit or obliterate it. If the first condition is present it may mean that the artery is not completely obliterated or that coarse collateral circulation is taking place or that the vertebral system is involved. If the opposite or contralateral artery is occluded, the- noise is usually altered by its. becoming louder. In patients with a slightly irritable carotid sinus a slowing or loss of intensity of the bruit may readily be noted. Normal blood flow does not give rise to a bruit. Vibration arising under certain conditions and noted as rhythmic noises may theoretically be caused either in the blood stream or in the blood vessel wall. Most bruits have their origin in the vibrations of the blood itself. A change in the radius of the vessel and the velocity of the blood stream is important in producing a murmur. Increase in the size of the vessels in arterial aneurysm may be a cause. The production of a high velocity is significant in other vessel disorders. The rate of speed may be altered by changes in blood pressure or in the caliber of the vessels since velocity is directly proportionate to pressure and inversely proportionate to the vessel size. It is for that reason that a murmur may become audible when the pulse pressure is increased by exercise or stimulant. It must be emphasized that a change in the blood vessel size must be abrupt in order to produce vibrations. Gradual convergence or divergence of the vessel wall tends to overcome the vibrations in the blood stream itself. A murmur heard directly over a narrowed segment of an artery is loud and of long duration. Bruits caused by arteriovenous fistulas are usually continuous, socalled to-and-fro murmurs, since the changes in frequency and amplitude during the systolic and diastolic phases may be markedly pronounced. The to-and-fro murmur may be changed to a systolic murmur if the large vein which drains the artery is occluded. This is true only if the fistula is unilateral as in the carotid-cavernous sinus fistula. In a few instances fistulas may be bilateral. The size of the opening between the artery and the vein or sinus greatly alters the character of the noise. This is also true if the lumen of an artery is abruptly constricted in varying degrees. If the constriction by an arteriosclerotic plaque, for instance, is at a low level, bruit occurs in the late diastole. As the constriction increases, the noise is best heard in systole and becomes louder. Gupta and Wiggers4 found in experimental
James L. Poppen
886
coarctation that aortic murmurs were produced when 60 per cent of the lumen was constricted. The murmurs were loudest when 73 per cent of the lumen was constricted and no longer audible at 78 per cent. Edwards and Levine 2, 3 have studied extensively murmurs produced by diseases that cause change in the peripheral arteries. They found that a considerable degree of accuracy can be obtained in locating the site of constriction or fistula. They stated that a murmur is often heard over a wide area, but is most intense directly over the fistula. Unfortunately, because of the sounding board effect of the skull, one cannot find, in most instances, the exact site of the condition that causes the bruit although there is no question but that the noise is usually greatest in the immediate vicinity of the disease. Since many of these intracranial conditions, however, are situated in the midline, it can easily be understood why the noise can be heard well bilaterally. In Paget's disease I believe the bruit is caused by the narrowing of the cranial foramina at the base, constricting the lumen of the vessels. I have not heard a bruit or murmur in a patient with Paget's disease unless there was marked involvement of the base of the skull. Adson1 emphasized the fact that atheromatous plaques in the subclavian artery caused by constant irritation of a cervical rib or band compressing the artery could cause murmurs. REFERENCES 1. Adson, A. W.: Surgical treatment for symptoms produced by cervical ribs and scalenus anticus muscle. Surg., Gynec. & Obst. 85: 687-700 (Dec.) 1947. 2. Edwards, E. A. and Levine, H. D.: Peripheral vascular murmurs; Mechanism of production and diagnostic significance. A.M.A. Arch. Int. Med. 90: 284-300 (Sept.) 1952. 3. Edwards, E. A. and Levine, H. D.: The murmur of peripheral arteriovenous fistula. New England J. Med. 247: 502-505 (Oct. 2) 1952. 4. Gupta, T. C. and Wiggers, C. J.: Basic hemodynamic changes produced by aortic coarctation of different degrees. Circulation 3: 17-31 (Jan.) 1951. 5. Hoover, W. B.: Left carotid jugular arteriovenous communication. S. CLIN. NORTH AMERICA 9: 1453-1457 (Dec.) 1929. 6. Richardson, C. and Kofman, 0.: Cranial bruit with intracranial saccular aneurysms Tr. Am. Neurol. A. 76: 151-154, 1951.