•
Angiographic Features of Subdural Empyema 1
•
Neuroradiology
Kwang S. Kim, M.D., Peter E. Weinberg, M.D., and Melvin Magidson, M.D. Subdural empyema, a relatively rare intracranial suppurative disease, is a surgical emergency and requires early diagnosis in order to ensure patient survival. Subdural empyema should be considered with one or a combination of the following in conjunction with an extracerebral collection: (a) an irregular border of the extracerebral collection; (b) a thickened vascular wall of dura; (c) a semilunar avascular zone on the lateral view; (d) spasm of the large arteries at the base of the brain with or without segmental arterial dilatation; (e) multiple peripheral arterial occlusions; and (f) enlargement of the anterior falx artery. Four verified cases are presented. INDEX TERMS: Brain, inflammation. Brain, infection. Meninges Radiology 118:621-625, March 1976
•
• is a relatively rare intracranial suppurative disease. Until the advent of antibiotics, the mortality rate from this condition approached 100%, but this has now been reduced to about 30% (2, 10). Since subdural empyema is a surgical emergency (1,2, 19), early diagnosis is imperative.
neck stiffness, a left-central facial weakness and left hemiparesis. Deep tendon reflexes were greater on the left and a positive Babinski sign was present bilaterally. A right brachial angiogram obtained on the night of admission showed poor filling of the intracranial branches of the right internal carotid artery. This was presumed to be due to mechanical failure of the pressure injector. A relatively thin extracerebral avascular zone was seen over the right cerebral convexity with a mild degree of shift of the midline structures to the left. Subdural hematoma was diagnosed, but it was not considered large enough to warrant surgery. Because the patient's condition had deteriorated, right carotid angiography was performed. The AP views demonstrated a thin (8mm) avascular extracerebral zone over the right convexity (Fig. 1). The anterior cerebral artery was not visualized, and presumably was supplied from the left side.
UBDURAL EMPYEMA
S
CASE REPORTS CASE I. A 54-year-old black man was hospitalized because of headaches' of six days' duration. One day prior to admission, he experienced a generalized seizure which was followed by left-sided weakness. On admission, he had a temperature of 101°F and blood pressure of 170/80 mm Hg. The patient was semicomatose with
Fig. 1. CASE I. Right common carotid injection, anteroposterior projection. Note separation of the convexity branches of the middle cerebral artery (open arrowheads) from the inner table of the skull (interrupted line of dots). The small midline vessel (closed arrowhead) is the anterior falx artery. Fig. 2. Same case. Right common carotid injection, lateral projection. The tortuous vessel originating from the ophthalmic artery and extending superiorly is the enlarged anterior falx artery (closed arrowheads). There is an avascular zone in the frontal and anterior parietal regions (arrows). 1 From the Department of Radiology, Northwestern Memorial Hospital and the McGaw Medical Center of Northeastern University, Chicago, III. Revised manuscript accepted for publication in November 1975. shan
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March 1976
Fig. 3. CASE II. Left common carotid injection, anteroposterior projection. Note separation of the convexity branches of the middle cerebral artery (open arrowheads) from the inner table of the skull (interrupted line of dots). The anterior cerebral artery is displaced to the right side (closed arrows). Fig. 4. Same case. Left common carotid injection, lateral projection. There are multiple peripheral arterial occlusions in the parietal region (arrows). The enlarged and tortuous anterior falx artery is seen originating from the ophthalmic artery and coursing superiorly (closed arrowheads).
The internal cerebral vein was shifted 4 mm to the left and lateral views demonstrated a prominent anterior falx artery which extended more than 8 cm above the cribriform plate (Fig. 2). A semilunarshaped avascular zone seen over the frontal and anterior parietal regions measured 11 cm in length and 5 cm in width with its convexity directed towards the brain surface. This avascular zone persisted throughout the arterial, capillary and venous phases. The superior sagittal sinus was patent. Multiple burr holes were immediately made and a thick membrane was incised, permitting drainage of over 100 ml of creamy pus. The culture revealed E. coli. Antibiotic therapy produced progressive clinical improvement. CASE II. A 35-year-old white man with a history of recurrent frontal sinusitis suffered an excruciating headache on the day prior to admission to an outside hospital where antibiotic therapy was begun. On the following day, dilatation of the left pupil was noted and the patient was transferred to our own institution with a temperature of 101.4°F and blood pressure of 110/60 mm Hg. There was a lett third nerve palsy, right facial weakness, right hemiparesis and a right Babinski sign. A lumbar puncture revealed an opening pressure of 400 mm H2 0 . The cerebrospinal fluid contained a few white blood cells. A left carotid angiogram revealed a thin (8mm), diffuse extracerebral avascular zone over the left cerebral hemisphere (Fig. 3). The midline structures were shifted more than 1 cm to the right. A prominent anterior falx artery extended more than 9 cm above the cribriform plate. Multiple peripheral arterial occlusions were found in the parietal region (Fig. 4). A large amount of purulent material was drained through left frontal and left temporal burr holes. No organisms were identified on culture. On the day following surgery, plain films and polytomograms of
the paranasal sinuses showed evidence of a pyocele in the left frontal sinus. Surgical drainage of pus from the left frontal pyocele was subsequently performed. The patient's condition improved.
CASE III. An 11-year-old black girl was hospitalized because of lethargy, behavioral Change, weakness of the left hand, and fever. During the two days prior to admission, she had complained of rightsided headache and neck pain. Admission temperature was 99.6°F and blood pressure was 95/65 mm Hg. The patient was drowsy and restless. Physical examination revealed a left central facial palsy and left hemiparesis. A lumbar spinal puncture showed an opening pressure of 240 mm H2 0 . The cerebrospinal fluid contained 42 white blood cells and 25 red blood cells per cubic millimeter. Right carotid angiography on the day after admission showed a 1-cm shitt of the anterior cerebral artery to the lett. An 8mm-wide extracerebral avascular zone was present over the right convexity (Fig. 5). Spasm of the supraclinoid portion of the internal carotid artery and proximal portion of the anterior and middle cerebral arteries was noted. In addition, segmental arterial dilatation was seen, primarily involving the intrasylvian branches of the middle cerebral artery. There were multiple peripheral arterial occlusions in the parietal area (Fig. 6). Immediate surgery was performed and thick purulent material was drained from beneath the dura through three separate burr holes. Culture of this material revealed alpha-hemolytic streptococci. The patient began to improve on the third postoperative day but remained lethargic. Because of suspected hydrocephalus, a second right carotid angiogram was obtained which showed resolution of the previously present spasm and segmental middle cerebral artery dilatation without any residual vascular occlusions (Fig. 7). There was no
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angiographic evidence of hydrocephalus. The patient's condition gradually improved and she was discharged. CASE IV. A 38-year-old white man was hospitalized because of a one-week history of headache, "sore neck," and vomiting. The patient was unconscious, but responded to painful stimuli. The right pupil was larger than the left. The left eye deviated laterally and there was a left central facial palsy. Purulent material discharged
623
Neuroradiology
from both external auditory canals and there was moderate neck stiffness. A lumbar spinal puncture revealed an opening pressure of 250 mm H2 0 . The cerebrospinal fluid contained 83 mg/100 ml of protein and no cells. Right carotid angiography revealed a thin, extracerebral avascular zone over the right convexity. There was marked shift of the anterior cerebral artery and internal cerebral vein to the left. A hypertrophied anterior falx artery was demonstrated. Spasm of the larger arteries
KWANG S. KIM AND OTHERS
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Fig. 8. CASE IV. Right common carotid injection, lateral projection. Spasm involves the supraclinoid segment of the internal carotid artery (single arrow). The anterior falx artery is enlarged and is visualized over an abnormally long course (closed arrowheads). Multiple peripheral occlusions involve branches of the middle cerebral artery in the frontal and parietal regions (open arrowheads).
at the base of the brain was noted along with multiple peripheral arterial occlusions inthe frontal and parietal areas (Figs. 8 and 9). An emergency right frontal temporal craniotomy revealed a large subdural collection of pus within a membrane. Proteus mirabilis was cultured. Postoperatively there was gradual improvement. ENT consultation reported bilateral cholesteatomas with erosion of the tegmen tympani proven surgically. The patient again did well postoperatively and wassubsequently discharged.
March 1976
empyema. Ferris et et. (8) described 6 cases of subdural empyema, one of which was associated with septic sagittal sinus thrombosis with meningitis and multiple arterial occlusions, arteriovenous shunting and spasm of the large arteries at the base of the brain. The pattern of an interhemispheric subdural empyema has been described as an avascular area along the falx cerebri on the anteroposterior view with displacement of the anterior cerebral artery branches away from the midline (10, 11, 15, 18). The importance of preoperative localization of an interhemispheric collection has been emphasized. An extracerebral subdural collection was present in all of our patients. None demonstrated a thickened vascular wall of the dura, and an irregular border of the subdural collection was difficult to appreciate. Only one case revealed the semilunar avascular zone on the lateral view with the convexity pointing towards the brain surface. In 2 patients (CASES III and IV), there was evidence of narrowing of the supraclinoid portion of the internal carotid artery and proximal segments of the anterior and middle cerebral arteries. CASE III also revealed segmental arterial dilatation primarily involving the intrasylvian branches of the middle cerebral artery. CASE IV, however, showed equivocal evidence of segmental arterial dilatation involving the branches of the middle cerebral artery. Vasoconstriction in connection with cere-
DISCUSSION In cases of subdural empyema nonspecific angiographic findings of an extracerebral collection are encountered similar to those seen with subdural hematoma. The literature has little to offer with respect to specific angiographic findings of subdural empyema. Weber (17) described visualization of the inflammatory wall as a finding specific for subdural empyema in the presence of an extracerebral collection. Feiring et a/. (6) reported similar observations in subdural empyema and described a circular thick zone of hypervascularity around an avascular area seen in a case of chronic subdural abscess. Cornelle et a/. (3) described the angiographic appearance of subdural empyema, emphasizing the irregular image in contrast with the regular image seen in subdural hematoma. Ferris et a/. (7) presented a case of subdural empyema with angiographic findings of (a) an irregular border of the extra-axial collection in contrast to the smooth wall of subdural hematoma, (b) a thickened vascular wall of dura seen on the AP and lateral views and (c) a semilunar avascular zone noted on 'the lateral view. The authors presented these angiographic features as a definitive triad in subdural
Fig. 9. Same case. Right common carotid injection, lateral projection. The anterior falx artery is enlarged and tortuous and is displaced away from the inner table of the skull (three large arrows). Note stretching and separation of branches of the anterior cerebral artery (two small arrows) and posterior displacement of the main branches of the anterior cerebral artery (open arrowhead).
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bral inflammatory disease is well known (5, 8, 9, 12, 13) but there are relatively few reports of associated vasodilatation (5, 9, 12). In CASE III, a follow-up angiogram demonstrated resolution of both the arterial narrowing at the base of the brain and the segmental middle cerebral arterial dilatation. In all of our patients, multiple occlusions involving the distal branches of the middle cerebral artery were seen. Multiple peripheral arterial occlusions related to various types of meningitis have been described (5, 8, 12, 13). Follow-up angiograms after treatment in CASES I and III showed resolution of the arterial occlusions seen in the initial angiograms. Enlargement of the anterior falx artery was present in 3 of our 4 cases, a finding described by Pollock and Newton (16) in a variety of pathological conditions. They mention a case of chronic meningitis in which the anterior falx artery was enlarged, presumably as a result of increased vascularity associated with the inflammatory process. This angiographic finding has not been described in other case presentations of subdural empyema. The authors (K.S.K., P.E.W.) have observed a markedly enlarged anterior falx artery in a patient with epidural empyema in the frontal region (Fig. 9). We believe that the enlargement of this vessel in both subdural and epidural empyemas is due to hypervascularity secondary to pachymeningeal involvement by the in.. flammatory process. A chronic subdural hematoma may cause enlargement of this vessel but in both our experience and reports in the literature, such a finding is very rare. The differential diagnosis between epidural and subdural empyema may be difficult. Vascular displacement which serves to differentiate between epidural and subdural hematoma is simUarly used to differentiate between subdural and epidural collections of pus. These angiographic features include displacement of meninqeal arteries and dural sinuses away from the inner table of the skull. However, the presence of an enlarged anterior falx artery displaced away from the inner table of the skull should suggest epidural empyema.
SUMMARY The previously described specific angiographic findings of subdural empyema include: (a) An irregular border of the extracerebral collection (b) A thickened vascular wall of dura, and (c) A semilunar avascular zone on the lateral view. In addition, the following angiographic findings due to leptomeningeal and pachymeningeal inflammatory processes may be present:
Neuroradiology
Spasm of the large arteries at the base of the brain with or without segmental arterial dilatation (e) Multiple peripheral arterial occlusions, and (f) Enlargement of the anterior falx artery. A diagnosis of subdural empyema should be considered with one or a combination of the above findings in conjunction with an extracerebral collection. (d)
Department of Radiology Northwestern Memorial Hospital Superior Street and Fairbanks Court Chicago, III. 60611
REFERENCES 1. Annotations: Subdural intracranial empyema. Lancet 1: 538-539,6 Mar 1965 2. Bhandari YS, Sarkari NBS: Subdural empyema. J Neurosurg 32:35-39, Jan 1970 3. Cornelis RG, Van denBergh R, Stroobandt G: [Carotid angiogram in subdural empyema.] Ann Radiol 6:143-145, 1963 (in French) 4. Courville CB: Subdural empyema secondary to purulent frontal sinusitis; clinicopathologic study of 42 cases verified at autopsy. Arch OtolaryngoI39:211-230, Mar 1944 5. Davis DO, Dilenge 0, Schlaepfer W: Arterial dilatation in purulent meningitis; a case report. J Neurosurg 32:112-115, Jan 1970 6. Feiring EH, Shapiro JH, Lubetsky HW: The ring-like vascular pattern in cerebral arteriography. Am J Roentgenol 89:385-390, Feb 1963 7. Ferris EJ, Ciembroniewicz J: Subdural empyema. Report of a casedemonstrating the unusual angiographic triad. AmJ Roentgenol 92:838-943, Oct 1964 8. Ferris EJ, Rudikoff JC, Shapiro JH: Cerebral angiography of bacterial infection. Radiology 90:727-734, Apr 1968 9. Greitz T: Angiography in tuberculous meningitis. Acta Radiol [Diag] 2:369-378, Sep 1964 10. Hitchcock E, Alexander A: Subdural empyema; a review of 29 cases. J Neurol Neurosurg Psychiatr 27:422-434, Oct 1964 11. Kristiansen K, Zimmer J: Interhemispheric subdural abscess. Br J Radiol 31:278-279, May 1958 12. Leeds NE, Goldberg HI: Angiographic manifestations in cerebral inflammatory disease. Radiology 98:595-604, Mar 1971 13. Lyons, EL, Leeds NE: The angiographic demonstration of arterial vascular disease in purulent meningitis. Report of a case. Radiology 88:935-938, May 1967 14. McLawrin RL: Subdural Infection, Cranial and Intracranial Suppuration. Gurdjian ES, ed. Springfield, tll., Thomas, 1969, pp 73-88 15. Patton JT, Hitchcock E: Angiographic features of falcine subdural empyema. Clin RadioI19:229-232, 1968 16. Pollock JA, Newton TH: The anterior falx artery: normal andpathologic anatomy. Radiology 91:1089-1095, Dec 1968 17. Weber G: Subdurale Empyeme und Abszesse im Carotisangiogramm. Schweiz Med Wochenschr 92:1571-1573, 1 Dec 1962 18. Wilkins RH, Goree JA: Interhemispheric subdural empyema: angiographic appearance. J Neurosurg 32:459-462, Apr 1970 19. Woodhall B: Osteomyelitis and epl-, extra-, and subdural ebscesses. Clin Neurosurg 14:239-255, 1966
Angiographic Features of Subdural Empyema 1
•
Neuroradiology
Kwang S. Kim, M.D., Peter E. Weinberg, M.D., and Melvin Magidson, M.D. Subdural empyema, a relatively rare intracranial suppurative disease, is a surgical emergency and requires early diagnosis in order to ensure patient survival. Subdural empyema should be considered with one or a combination of the following in conjunction with an extracerebral collection: (a) an irregular border of the extracerebral collection; (b) a thickened vascular wall of dura; (c) a semilunar avascular zone on the lateral view; (d) spasm of the large arteries at the base of the brain with or without segmental arterial dilatation; (e) multiple peripheral arterial occlusions; and (f) enlargement of the anterior falx artery. Four verified cases are presented. INDEX TERMS: Brain, inflammation. Brain, infection. Meninges Radiology 118:621-625, March 1976
•
• is a relatively rare intracranial suppurative disease. Until the advent of antibiotics, the mortality rate from this condition approached 100%, but this has now been reduced to about 30% (2, 10). Since subdural empyema is a surgical emergency (1,2, 19), early diagnosis is imperative.
neck stiffness, a left-central facial weakness and left hemiparesis. Deep tendon reflexes were greater on the left and a positive Babinski sign was present bilaterally. A right brachial angiogram obtained on the night of admission showed poor filling of the intracranial branches of the right internal carotid artery. This was presumed to be due to mechanical failure of the pressure injector. A relatively thin extracerebral avascular zone was seen over the right cerebral convexity with a mild degree of shift of the midline structures to the left. Subdural hematoma was diagnosed, but it was not considered large enough to warrant surgery. Because the patient's condition had deteriorated, right carotid angiography was performed. The AP views demonstrated a thin (8mm) avascular extracerebral zone over the right convexity (Fig. 1). The anterior cerebral artery was not visualized, and presumably was supplied from the left side.
UBDURAL EMPYEMA
S
CASE REPORTS CASE I. A 54-year-old black man was hospitalized because of headaches' of six days' duration. One day prior to admission, he experienced a generalized seizure which was followed by left-sided weakness. On admission, he had a temperature of 101°F and blood pressure of 170/80 mm Hg. The patient was semicomatose with
Fig. 1. CASE I. Right common carotid injection, anteroposterior projection. Note separation of the convexity branches of the middle cerebral artery (open arrowheads) from the inner table of the skull (interrupted line of dots). The small midline vessel (closed arrowhead) is the anterior falx artery. Fig. 2. Same case. Right common carotid injection, lateral projection. The tortuous vessel originating from the ophthalmic artery and extending superiorly is the enlarged anterior falx artery (closed arrowheads). There is an avascular zone in the frontal and anterior parietal regions (arrows). 1 From the Department of Radiology, Northwestern Memorial Hospital and the McGaw Medical Center of Northeastern University, Chicago, III. Revised manuscript accepted for publication in November 1975. shan
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KIM AND OTHERS
March 1976
Fig. 3. CASE II. Left common carotid injection, anteroposterior projection. Note separation of the convexity branches of the middle cerebral artery (open arrowheads) from the inner table of the skull (interrupted line of dots). The anterior cerebral artery is displaced to the right side (closed arrows). Fig. 4. Same case. Left common carotid injection, lateral projection. There are multiple peripheral arterial occlusions in the parietal region (arrows). The enlarged and tortuous anterior falx artery is seen originating from the ophthalmic artery and coursing superiorly (closed arrowheads).
The internal cerebral vein was shifted 4 mm to the left and lateral views demonstrated a prominent anterior falx artery which extended more than 8 cm above the cribriform plate (Fig. 2). A semilunarshaped avascular zone seen over the frontal and anterior parietal regions measured 11 cm in length and 5 cm in width with its convexity directed towards the brain surface. This avascular zone persisted throughout the arterial, capillary and venous phases. The superior sagittal sinus was patent. Multiple burr holes were immediately made and a thick membrane was incised, permitting drainage of over 100 ml of creamy pus. The culture revealed E. coli. Antibiotic therapy produced progressive clinical improvement. CASE II. A 35-year-old white man with a history of recurrent frontal sinusitis suffered an excruciating headache on the day prior to admission to an outside hospital where antibiotic therapy was begun. On the following day, dilatation of the left pupil was noted and the patient was transferred to our own institution with a temperature of 101.4°F and blood pressure of 110/60 mm Hg. There was a lett third nerve palsy, right facial weakness, right hemiparesis and a right Babinski sign. A lumbar puncture revealed an opening pressure of 400 mm H2 0 . The cerebrospinal fluid contained a few white blood cells. A left carotid angiogram revealed a thin (8mm), diffuse extracerebral avascular zone over the left cerebral hemisphere (Fig. 3). The midline structures were shifted more than 1 cm to the right. A prominent anterior falx artery extended more than 9 cm above the cribriform plate. Multiple peripheral arterial occlusions were found in the parietal region (Fig. 4). A large amount of purulent material was drained through left frontal and left temporal burr holes. No organisms were identified on culture. On the day following surgery, plain films and polytomograms of
the paranasal sinuses showed evidence of a pyocele in the left frontal sinus. Surgical drainage of pus from the left frontal pyocele was subsequently performed. The patient's condition improved.
CASE III. An 11-year-old black girl was hospitalized because of lethargy, behavioral Change, weakness of the left hand, and fever. During the two days prior to admission, she had complained of rightsided headache and neck pain. Admission temperature was 99.6°F and blood pressure was 95/65 mm Hg. The patient was drowsy and restless. Physical examination revealed a left central facial palsy and left hemiparesis. A lumbar spinal puncture showed an opening pressure of 240 mm H2 0 . The cerebrospinal fluid contained 42 white blood cells and 25 red blood cells per cubic millimeter. Right carotid angiography on the day after admission showed a 1-cm shitt of the anterior cerebral artery to the lett. An 8mm-wide extracerebral avascular zone was present over the right convexity (Fig. 5). Spasm of the supraclinoid portion of the internal carotid artery and proximal portion of the anterior and middle cerebral arteries was noted. In addition, segmental arterial dilatation was seen, primarily involving the intrasylvian branches of the middle cerebral artery. There were multiple peripheral arterial occlusions in the parietal area (Fig. 6). Immediate surgery was performed and thick purulent material was drained from beneath the dura through three separate burr holes. Culture of this material revealed alpha-hemolytic streptococci. The patient began to improve on the third postoperative day but remained lethargic. Because of suspected hydrocephalus, a second right carotid angiogram was obtained which showed resolution of the previously present spasm and segmental middle cerebral artery dilatation without any residual vascular occlusions (Fig. 7). There was no
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angiographic evidence of hydrocephalus. The patient's condition gradually improved and she was discharged. CASE IV. A 38-year-old white man was hospitalized because of a one-week history of headache, "sore neck," and vomiting. The patient was unconscious, but responded to painful stimuli. The right pupil was larger than the left. The left eye deviated laterally and there was a left central facial palsy. Purulent material discharged
623
Neuroradiology
from both external auditory canals and there was moderate neck stiffness. A lumbar spinal puncture revealed an opening pressure of 250 mm H2 0 . The cerebrospinal fluid contained 83 mg/100 ml of protein and no cells. Right carotid angiography revealed a thin, extracerebral avascular zone over the right convexity. There was marked shift of the anterior cerebral artery and internal cerebral vein to the left. A hypertrophied anterior falx artery was demonstrated. Spasm of the larger arteries
KWANG S. KIM AND OTHERS
624
Fig. 8. CASE IV. Right common carotid injection, lateral projection. Spasm involves the supraclinoid segment of the internal carotid artery (single arrow). The anterior falx artery is enlarged and is visualized over an abnormally long course (closed arrowheads). Multiple peripheral occlusions involve branches of the middle cerebral artery in the frontal and parietal regions (open arrowheads).
at the base of the brain was noted along with multiple peripheral arterial occlusions inthe frontal and parietal areas (Figs. 8 and 9). An emergency right frontal temporal craniotomy revealed a large subdural collection of pus within a membrane. Proteus mirabilis was cultured. Postoperatively there was gradual improvement. ENT consultation reported bilateral cholesteatomas with erosion of the tegmen tympani proven surgically. The patient again did well postoperatively and wassubsequently discharged.
March 1976
empyema. Ferris et et. (8) described 6 cases of subdural empyema, one of which was associated with septic sagittal sinus thrombosis with meningitis and multiple arterial occlusions, arteriovenous shunting and spasm of the large arteries at the base of the brain. The pattern of an interhemispheric subdural empyema has been described as an avascular area along the falx cerebri on the anteroposterior view with displacement of the anterior cerebral artery branches away from the midline (10, 11, 15, 18). The importance of preoperative localization of an interhemispheric collection has been emphasized. An extracerebral subdural collection was present in all of our patients. None demonstrated a thickened vascular wall of the dura, and an irregular border of the subdural collection was difficult to appreciate. Only one case revealed the semilunar avascular zone on the lateral view with the convexity pointing towards the brain surface. In 2 patients (CASES III and IV), there was evidence of narrowing of the supraclinoid portion of the internal carotid artery and proximal segments of the anterior and middle cerebral arteries. CASE III also revealed segmental arterial dilatation primarily involving the intrasylvian branches of the middle cerebral artery. CASE IV, however, showed equivocal evidence of segmental arterial dilatation involving the branches of the middle cerebral artery. Vasoconstriction in connection with cere-
DISCUSSION In cases of subdural empyema nonspecific angiographic findings of an extracerebral collection are encountered similar to those seen with subdural hematoma. The literature has little to offer with respect to specific angiographic findings of subdural empyema. Weber (17) described visualization of the inflammatory wall as a finding specific for subdural empyema in the presence of an extracerebral collection. Feiring et a/. (6) reported similar observations in subdural empyema and described a circular thick zone of hypervascularity around an avascular area seen in a case of chronic subdural abscess. Cornelle et a/. (3) described the angiographic appearance of subdural empyema, emphasizing the irregular image in contrast with the regular image seen in subdural hematoma. Ferris et a/. (7) presented a case of subdural empyema with angiographic findings of (a) an irregular border of the extra-axial collection in contrast to the smooth wall of subdural hematoma, (b) a thickened vascular wall of dura seen on the AP and lateral views and (c) a semilunar avascular zone noted on 'the lateral view. The authors presented these angiographic features as a definitive triad in subdural
Fig. 9. Same case. Right common carotid injection, lateral projection. The anterior falx artery is enlarged and tortuous and is displaced away from the inner table of the skull (three large arrows). Note stretching and separation of branches of the anterior cerebral artery (two small arrows) and posterior displacement of the main branches of the anterior cerebral artery (open arrowhead).
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ANGIOGRAPHIC FEATURES OF SUBDURAL EMPYEMA
bral inflammatory disease is well known (5, 8, 9, 12, 13) but there are relatively few reports of associated vasodilatation (5, 9, 12). In CASE III, a follow-up angiogram demonstrated resolution of both the arterial narrowing at the base of the brain and the segmental middle cerebral arterial dilatation. In all of our patients, multiple occlusions involving the distal branches of the middle cerebral artery were seen. Multiple peripheral arterial occlusions related to various types of meningitis have been described (5, 8, 12, 13). Follow-up angiograms after treatment in CASES I and III showed resolution of the arterial occlusions seen in the initial angiograms. Enlargement of the anterior falx artery was present in 3 of our 4 cases, a finding described by Pollock and Newton (16) in a variety of pathological conditions. They mention a case of chronic meningitis in which the anterior falx artery was enlarged, presumably as a result of increased vascularity associated with the inflammatory process. This angiographic finding has not been described in other case presentations of subdural empyema. The authors (K.S.K., P.E.W.) have observed a markedly enlarged anterior falx artery in a patient with epidural empyema in the frontal region (Fig. 9). We believe that the enlargement of this vessel in both subdural and epidural empyemas is due to hypervascularity secondary to pachymeningeal involvement by the in.. flammatory process. A chronic subdural hematoma may cause enlargement of this vessel but in both our experience and reports in the literature, such a finding is very rare. The differential diagnosis between epidural and subdural empyema may be difficult. Vascular displacement which serves to differentiate between epidural and subdural hematoma is simUarly used to differentiate between subdural and epidural collections of pus. These angiographic features include displacement of meninqeal arteries and dural sinuses away from the inner table of the skull. However, the presence of an enlarged anterior falx artery displaced away from the inner table of the skull should suggest epidural empyema.
SUMMARY The previously described specific angiographic findings of subdural empyema include: (a) An irregular border of the extracerebral collection (b) A thickened vascular wall of dura, and (c) A semilunar avascular zone on the lateral view. In addition, the following angiographic findings due to leptomeningeal and pachymeningeal inflammatory processes may be present:
Neuroradiology
Spasm of the large arteries at the base of the brain with or without segmental arterial dilatation (e) Multiple peripheral arterial occlusions, and (f) Enlargement of the anterior falx artery. A diagnosis of subdural empyema should be considered with one or a combination of the above findings in conjunction with an extracerebral collection. (d)
Department of Radiology Northwestern Memorial Hospital Superior Street and Fairbanks Court Chicago, III. 60611
REFERENCES 1. Annotations: Subdural intracranial empyema. Lancet 1: 538-539,6 Mar 1965 2. Bhandari YS, Sarkari NBS: Subdural empyema. J Neurosurg 32:35-39, Jan 1970 3. Cornelis RG, Van denBergh R, Stroobandt G: [Carotid angiogram in subdural empyema.] Ann Radiol 6:143-145, 1963 (in French) 4. Courville CB: Subdural empyema secondary to purulent frontal sinusitis; clinicopathologic study of 42 cases verified at autopsy. Arch OtolaryngoI39:211-230, Mar 1944 5. Davis DO, Dilenge 0, Schlaepfer W: Arterial dilatation in purulent meningitis; a case report. J Neurosurg 32:112-115, Jan 1970 6. Feiring EH, Shapiro JH, Lubetsky HW: The ring-like vascular pattern in cerebral arteriography. Am J Roentgenol 89:385-390, Feb 1963 7. Ferris EJ, Ciembroniewicz J: Subdural empyema. Report of a casedemonstrating the unusual angiographic triad. AmJ Roentgenol 92:838-943, Oct 1964 8. Ferris EJ, Rudikoff JC, Shapiro JH: Cerebral angiography of bacterial infection. Radiology 90:727-734, Apr 1968 9. Greitz T: Angiography in tuberculous meningitis. Acta Radiol [Diag] 2:369-378, Sep 1964 10. Hitchcock E, Alexander A: Subdural empyema; a review of 29 cases. J Neurol Neurosurg Psychiatr 27:422-434, Oct 1964 11. Kristiansen K, Zimmer J: Interhemispheric subdural abscess. Br J Radiol 31:278-279, May 1958 12. Leeds NE, Goldberg HI: Angiographic manifestations in cerebral inflammatory disease. Radiology 98:595-604, Mar 1971 13. Lyons, EL, Leeds NE: The angiographic demonstration of arterial vascular disease in purulent meningitis. Report of a case. Radiology 88:935-938, May 1967 14. McLawrin RL: Subdural Infection, Cranial and Intracranial Suppuration. Gurdjian ES, ed. Springfield, tll., Thomas, 1969, pp 73-88 15. Patton JT, Hitchcock E: Angiographic features of falcine subdural empyema. Clin RadioI19:229-232, 1968 16. Pollock JA, Newton TH: The anterior falx artery: normal andpathologic anatomy. Radiology 91:1089-1095, Dec 1968 17. Weber G: Subdurale Empyeme und Abszesse im Carotisangiogramm. Schweiz Med Wochenschr 92:1571-1573, 1 Dec 1962 18. Wilkins RH, Goree JA: Interhemispheric subdural empyema: angiographic appearance. J Neurosurg 32:459-462, Apr 1970 19. Woodhall B: Osteomyelitis and epl-, extra-, and subdural ebscesses. Clin Neurosurg 14:239-255, 1966
