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Jugular bulb diverticula: Clinical and radiologic aspects
Jugular bulb diverticula: Clinical and radiologic aspects CEM BILGEN,
MD,
TAYFUN KIRAZLI,
MD,
FATIH OGUT,
MD,
and SECIL TOTAN,
OBJECTIVE: This study was performed to determine the clinical presentation of jugular diverticulum and its relevance with the extension of the lesion. STUDY DESIGN: The records and high-resolution CT scans of 1474 patients, with otologic symptoms or related clinical findings, were evaluated retrospectively. In 17 cases in which CT scans revealed the presence of jugular diverticulum, sensorineural symptoms were evaluated with respect to a reference line, perpendicular to the basal turn of the cochlea and tangent to the vestibule in axial CT scan images. RESULTS: When the extension of jugular diverticulum was posterior to the reference line, sensorineural symptoms with vertigo were dominant in most patients (72.7%) in this group. On the other hand, for the patients with anterior-extending jugular diverticulum, sensorineural symptoms without vertigo were detected in 50% of patients, whereas 33.3% had sensorineural symptoms with vertigo. CONCLUSION: This study revealed a relationship between the extension of jugular diverticulum and clinical symptoms. However, this relationship lacks statistical evidence because of the limited number of patients. (Otolaryngol Head Neck Surg 2003;128: 382-6.)
T he dome of the jugular bulb, which has a large physiologic range, lies beneath the floor of the tympanic cavity. Found in 3.5% to 7.6% of temporal bones, a high-riding jugular bulb, projecting into the middle ear, is not uncommon. When dehiscent, this anatomic variation may be associated with pulsatile tinnitus or conductive hearing loss.1-3 On the other hand, a jugular diverticulum (JD), considered a true venous anomaly, is an outpouching of the jugular bulb that extends superiorly, From the ENT Department, Medical School of Ege University. Reprint requests: Dr Cem Bilgen, Talatpasa Bulv No:35 / 5 35220 Alsancak, Izmir, Turkey; e-mail, cembilgen@hotmail. com. Copyright © 2003 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. 0194-5998/2003/$30.00 ⫹ 0 doi:10.1067/mhn.2003.32 382
MD,
Bornova-Izmir, Turkey
medially, and posteriorly in the petrous bone. Twenty-one reported cases exist in the Englishlanguage literature.2,4 In this article, the clinical presentation of JD and its relevance with the extension of JD in 17 patients are discussed. MATERIALS AND METHODS The records of 1474 patients who had undergone evaluation with high-resolution CT scan (HRCT) of the temporal bone because of an otologic symptom or related clinical findings were investigated at the ENT Department of Ege University Hospital, Izmir, Turkey, from January 1996 to June 2001. Seventeen patients, with 1.0 mm-thick high-resolution, bone algorithm CT scans that showed a JD projecting medially to the inner ear structures, were included in the study. The patients were comprised of 8 men and 9 women with a mean age of 41 years (range, 23 to 54 years). The data of the patients were reevaluated according to the sensorineural otologic symptoms (tinnitus, hearing loss, and vertigo) and audiologic test results. The extension of JD, on HRCT, was identified with respect to a reference line, perpendicular to the basal turn of the cochlea and tangent to the vestibule (Fig 1). With consideration of the relationship between the upper most extension of JD and this reference line, JD was classified as either an anterior-extending or a posterior-extending lesion (Fig 2). The presence of sensorineural symptoms with or without vertigo were compared with the extension of JD. RESULTS Of the 17 patients, 8 (47.05%) had undergone HRCT of the temporal bone as a preoperative evaluation because of a unilateral or bilateral chronic otitis media. The remaining 9 patients with progressive symptomatology underwent evaluation with HRCT in search of a temporal bone anomaly, such as wide cochlear aqueduct. JD was on the right side in 6 patients (35.2%) and on the left side in 11 patients (64.7%).
Otolaryngology– Head and Neck Surgery Volume 128 Number 3
Among these 17 patients, with JD seen on the HRCT of the temporal bone, 3 (17.6%) with chronic otitis media did not have any symptoms revealing an inner ear pathology. Fourteen patients (82.3%) had tinnitus and hearing loss of sensorineural or mixed type, and 10 patients (58.8%) also had vertigo. Tinnitus was constant in all patients (Table 1). Five of 8 patients with chronic otitis media had audiograms that showed a hearing loss of mixed type ipsilateral to JD, and the sensorineural component of the mixed type hearing loss was in the high frequency range in each patient’s audiogram. All of the 5 patients had high-pitched, constant ipsilateral tinnitus. Three of the 5 patients with mixed type hearing loss also had positional vertigo, especially when the head was turned ipsilaterally. Dix-Hallpike testing had negative results in these 3 patients. Of 8 patients with chronic otitis media, 3 with ipsilateral JD had moderate conductive hearing loss. None of the 3 patients had vertigo. Six patients had high-pitched, constant tinnitus and progressive sensorineural hearing loss. The audiograms revealed sensorineural hearing loss on the side of JD. Four of 6 patients had downsloping audiograms, whereas 2 patients had flat audiograms. Auditory brainstem response audiometry did not reveal a retrocochlear lesion in any of the 6 patients. Four patients had vertigo of positional type with short duration, which was pronounced with turning of the head or hyperflexing of the neck. Electronystagmographic results were normal in these 4 patients, including Dix-Hallpike testing. Three cases had episodic vertigo, hearing loss, and tinnitus, which suggested endolymphatic hydrops. Two cases were diagnosed with moderate sensorineural hearing loss in audiometry with down-sloping curve. One case had a flat, symmetric audiogram pattern of sensorineural hearing loss. Electronystagmographic results were normal in each case. Results of transtympanic electrocochleography showed summating potential/action potential (SP/AP) ratios of greater than 0.35 on the side of JD in all 3 cases. When the extension of JD with respect to the reference line was evaluated, 6 patients with anterior-extending and 11 patients with posterior-
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383
Fig 1. CT scan, axial section. Reference line is perpendicular to basal turn of cochlea and tangent to vestibule. C, Cochlea; V, vestibule.
Fig 2. Axial CT scan section shows (A) anterior-extending JD and (B) posterior-extending JD with respect to reference line. Black arrow, JD.
extending JD were identified (Table 2). Three (50%) of the 6 patients with anterior-extending JD
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Table 1. Clinical and radiologic features of patients. Patient
Age (y)/Gender
Side
Symptom/Finding
Extension of JD
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
36/Female 34/Female 23/Female 37/Female 38/Female 53/Male 41/Male 32/Female 50/Male 49/Male 54/Female 37/Male 47/Female 40/Male 38/Male 42/Male 46/Female
Right Right Left Left Left Left Right Right Left Left Left Right Left Left Left Right Left
SNHL, T, V MHL, T, V MHL, T MHL, T CHL SNHL, T CHL MHL, T, V SNHL, T, V SNHL, T, V(eh) SNHL, T, V CHL SNHL, T, V SNHL, T, V(eh) SNHL, T, V(eh) MHL, T, V SNHL, T
Anterior Anterior Anterior Anterior Anterior Anterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior
SNHL, Sensorineural hearing loss; MHL, mixed-type hearing loss; CHL, conductive-type hearing loss; T, tinnitus; V, vertigo; eh, endolymphatic hydrops.
Table 2. Symptom of vertigo with respect to extension of JD Extension of JD
Anterior Posterior Total
SNSⴙV
SNSⴚV
2 8 10
3 1 4
No SNS Total
1 2 3
6 11 17
SNS, Sensorineural symptoms; SNS⫹V, sensorineural symptoms with vertigo; SNS⫺V, sensorineural symptoms without vertigo
had symptoms of hearing loss and tinnitus without vertigo. CT scans of 2 of these 3 patients with sensorineural hearing loss and tinnitus showed encroachment of JD on the internal acoustic canal (Fig 3). Two patients (33.3%) had sensorineural hearing loss, tinnitus, and vertigo. One patient (16.6%) had neither sensorineural hearing loss and tinnitus nor vertigo. As for the 11 patients with posterior-extending JD, 8 patients (72.7%) had symptoms of sensorineural hearing loss, tinnitus, and vertigo. One patient (9.09%) noted only sensorineural hearing loss and tinnitus, and 2 cases (18.1%) were symptom-free with regard to sensorineural pathology. In this group of 11 patients, 3 patients with endolymphatic hydrops had CT scans that showed involvement of vestibular aqueduct by JD ipsilaterally (Fig 4).
No surgery was performed for the patients with sensorineural hearing loss, tinnitus, and vertigo of positional type. For 3 patients with endolymphatic hydrops, because they did not have debilitating vertigo and were managed well with medical treatment, neither surgical treatment nor ablative treatment with gentamicin was considered. DISCUSSION The anatomy of the venous system, especially that of jugular fossa, is highly variable.2 When compared with high-riding jugular bulb, a relatively common venous variation, JD is considered to be a rare venous anomaly, projecting toward the petrous apex. In the English-language literature, 21 cases with JD exist at this time.2-9 However, the rarity is questionable. This retrospective study presents 17 new cases identified through the records of 1474 patients with otologic problems and HRCT evaluations. This number compares with that of the literature. Because this disease was rarely reported before HRCT and a significant number of JD are likely asymptomatic, it is considered that the disease is underreported.4 Because magnetic resonance imaging (MRI) is not the method of choice in the diagnosis of a JD and because MRI is almost always the only radiologic technique used in the evaluation of sensorineural symptomatology, many cases of JD are probably
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Fig 3. Axial CT scan image shows encroachment of JD (white arrow) on internal acoustic canal (*).
Fig 4. Axial CT scan image shows JD (white arrow) involving expected path of vestibuler aqueduct. Lesion is in close proximity to endolymphatic sac (*).
not diagnosed. On the other hand, the cases are usually discovered at preoperative assessment with CT scan, as in 8 patients (47.05%) with chronic otitis media in this series or as in an individual finding on CT scan examination of the temporal bone. A female-to-male ratio was reported as 3:1.2 This ratio was found to be 1.12:1 in this study. Despite the known dominance of the jugular venous system on the right, left-side involvement is more common.4 A similar situation was found in this study: 11 left-sided and 6 right-sided involvements were identified. The relationship between JD and the clinical symptoms is questionable.2 However, with location in close proximity to the inner ear, this venous anomaly is considered to produce sensorineural symptoms, such as sensorineural hearing loss, tinnitus, and vertigo. These symptoms are related to the size and extension of the JD. Depending on the degree of extension, the cochlea, vestibular aqueducts, endolymphatic sac, posterior semicircular canal, and internal auditory canal can be involved.4 Encroachment of the JD on the internal auditory canal or the posterior semicircular canal results in a sensorineural hearing loss, whereas involvement of the vestibular aqueduct or the endolymphatic sac can produce Meniere’s diseaselike symptoms.10 In this series, sensorineural symptoms with the presence or absence of vertigo have been focused on in relation to the extension of the JD with respect to a reference line, perpendicular to the
basal turn of the cochlea and tangent to the vestibule. It has been noted that sensorineural symptoms with vertigo are generally produced when there is a posterior-extending JD (8/11 cases; 72.7%). On the other hand, an anterior-extending JD will likely cause sensorineural symptoms without vertigo (3/6 cases; 50%). Among these patients with anterior-extending JD, 2 cases (2/6; 33.3%) had sensorineural hearing loss, tinnitus, and vertigo. In consideration of the anterior position of the cochlea with respect to the posteriorly located vestibular labyrinth, these results correlate well in anatomoclinical aspect, despite the limited number of patients for a statistical correlation. As for more objective radiologic evidence, in 2 cases with sensorineural hearing loss and tinnitus, an apparent encroachment of JD on the internal auditory canal was shown. An involvement of the vestibular aqueduct was shown in 3 patients with endolymphatic hydrops. However, there were 3 symptom-free cases (17.6%), 2 with posterior-extending JD and 1 with anterior-extending JD. This situation may agree with the statement that the relationship between JD and clinical symptoms is questionable.2 On the other hand, because many of the cases in the literature and in this study have had progressive clinical symptoms starting in adulthood, an opposing question can be posed of whether JD represents a stable congenital anomaly or a pathologic progressive process that is capable of expanding to cause clinical symptoms. The answer to this question is still unclear, although reports document the growth
Otolaryngology– Head and Neck Surgery March 2003
386 BILGEN et al
of the lesion in a limited number of patients.2,6 For a reliable answer, comparison of follow-up images of the patients included in this series is being considered in a companion future study. A high-resolution bone algorithm CT scan with 1.0 mm-thick or 1.5 mm-thick images is the method of choice for evaluation of the vascular anatomy within the temporal bone. A JD is characterized by its continuity with the jugular bulb, its smooth edges, and the lack of aggressive pattern of bone destruction. The differential diagnosis includes jugular foramen lesions and petrous apex lesions.4 A JD will not typically be evident on standard spin MRI, unless an abnormal flow pattern is present. MRI venography would show these anomalies but is not routinely performed during evaluation of suspected seventh or eighth cranial nerve neoplasms. Because MRI alone is presently the standard method of diagnosis for cerebellopontine angle tumors, unexpected vascular anomalies may not be diagnosed before surgery.2 Patients with Meniere’s disease-like symptoms and CT scan evidence of involvement of the endolymphatic system by JD may benefit from surgical intervention, such as endolymphatic sac decompression. For the patients with sensorineural hearing loss or tinnitus and evidence of internal acoustic canal or posterior semicircular canal dehiscence, a decision for surgery, for instance, mastoidectomy and compression of the venous anomaly, should be made with careful evaluation of risks and benefits in each case.4,10 CONCLUSION JD is not an uncommon anomaly as previously believed. Partly because it is asymptomatic and
partly because it causes sensorineural symptoms, generally evaluated with MRI, which is not the method of choice in diagnosis, JD is probably underdiagnosed. Although a relationship between the extension of JD and clinical symptoms seemed to be identified in this study, the study still lacks of statistical evidence because of the limited number of patients in this series. Finally, the progressive nature of this pathology is still a question to be answered. REFERENCES
1. Edwards EA. Anatomic variations of the cranial venous sinuses: their relation to the effect of jugular compression in lumbar manometric tests. Arch Neurol Psychiatry 1931;26:801. 2. Pappas DG, Hoffman RA, Cohen NL, et al. Petrous jugular malposition (diverticulum). Otolaryngol Head Neck Surg 1993;109:847-52. 3. Presutti L, Laudadio P. Jugular bulb diverticula. ORL J Otorhinolaryngol Relat Spec 1991;53:57-60. 4. El-Kashlan HK, Arts HA, Gebarski S. Jugular diverticulum: clinical significans. Otolaryngol Head Neck Surg 2000;122:575-6. 5. Graham MD. The jugular bulb: its anatomic and clinical considerations in contemporary otology. Laryngoscope 1977;87:105-25. 6. Jahrsdorfer RA, Cail WS, Cantrell RW. Endolymphatic duct obstruction from a jugular bulb diverticulum. Ann Otol Rhinol Laryngol 1981;90:619-23. 7. Kennedy DW, El-Sirsy HH, Nager GT. The jugular bulb in otologic surgery: anatomic, clinical and surgical considerations. Otolaryngol Head Neck Surg 1986;94:6-15. 8. Shotton JC, Ludman H, Cox TCS. Temporal bone venous anomaly of surgical significans. J Laryngol Otol 1989; 103:101-6. 9. Stern J, Goldenberg M. Jugular bulb diverticula in medial petrous bone. AJR Am J Roentgenol 1980;134:959-61. 10. Grayeli AB, Bouccara D, Julien N, et al. Traitement chirurgical des vertiges induits par une ectasie du golfe de la jugulaire. Rev Laryngol Otol Rhinol 1995;116: 31-7.
MD,
TAYFUN KIRAZLI,
MD,
FATIH OGUT,
MD,
and SECIL TOTAN,
OBJECTIVE: This study was performed to determine the clinical presentation of jugular diverticulum and its relevance with the extension of the lesion. STUDY DESIGN: The records and high-resolution CT scans of 1474 patients, with otologic symptoms or related clinical findings, were evaluated retrospectively. In 17 cases in which CT scans revealed the presence of jugular diverticulum, sensorineural symptoms were evaluated with respect to a reference line, perpendicular to the basal turn of the cochlea and tangent to the vestibule in axial CT scan images. RESULTS: When the extension of jugular diverticulum was posterior to the reference line, sensorineural symptoms with vertigo were dominant in most patients (72.7%) in this group. On the other hand, for the patients with anterior-extending jugular diverticulum, sensorineural symptoms without vertigo were detected in 50% of patients, whereas 33.3% had sensorineural symptoms with vertigo. CONCLUSION: This study revealed a relationship between the extension of jugular diverticulum and clinical symptoms. However, this relationship lacks statistical evidence because of the limited number of patients. (Otolaryngol Head Neck Surg 2003;128: 382-6.)
T he dome of the jugular bulb, which has a large physiologic range, lies beneath the floor of the tympanic cavity. Found in 3.5% to 7.6% of temporal bones, a high-riding jugular bulb, projecting into the middle ear, is not uncommon. When dehiscent, this anatomic variation may be associated with pulsatile tinnitus or conductive hearing loss.1-3 On the other hand, a jugular diverticulum (JD), considered a true venous anomaly, is an outpouching of the jugular bulb that extends superiorly, From the ENT Department, Medical School of Ege University. Reprint requests: Dr Cem Bilgen, Talatpasa Bulv No:35 / 5 35220 Alsancak, Izmir, Turkey; e-mail, cembilgen@hotmail. com. Copyright © 2003 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. 0194-5998/2003/$30.00 ⫹ 0 doi:10.1067/mhn.2003.32 382
MD,
Bornova-Izmir, Turkey
medially, and posteriorly in the petrous bone. Twenty-one reported cases exist in the Englishlanguage literature.2,4 In this article, the clinical presentation of JD and its relevance with the extension of JD in 17 patients are discussed. MATERIALS AND METHODS The records of 1474 patients who had undergone evaluation with high-resolution CT scan (HRCT) of the temporal bone because of an otologic symptom or related clinical findings were investigated at the ENT Department of Ege University Hospital, Izmir, Turkey, from January 1996 to June 2001. Seventeen patients, with 1.0 mm-thick high-resolution, bone algorithm CT scans that showed a JD projecting medially to the inner ear structures, were included in the study. The patients were comprised of 8 men and 9 women with a mean age of 41 years (range, 23 to 54 years). The data of the patients were reevaluated according to the sensorineural otologic symptoms (tinnitus, hearing loss, and vertigo) and audiologic test results. The extension of JD, on HRCT, was identified with respect to a reference line, perpendicular to the basal turn of the cochlea and tangent to the vestibule (Fig 1). With consideration of the relationship between the upper most extension of JD and this reference line, JD was classified as either an anterior-extending or a posterior-extending lesion (Fig 2). The presence of sensorineural symptoms with or without vertigo were compared with the extension of JD. RESULTS Of the 17 patients, 8 (47.05%) had undergone HRCT of the temporal bone as a preoperative evaluation because of a unilateral or bilateral chronic otitis media. The remaining 9 patients with progressive symptomatology underwent evaluation with HRCT in search of a temporal bone anomaly, such as wide cochlear aqueduct. JD was on the right side in 6 patients (35.2%) and on the left side in 11 patients (64.7%).
Otolaryngology– Head and Neck Surgery Volume 128 Number 3
Among these 17 patients, with JD seen on the HRCT of the temporal bone, 3 (17.6%) with chronic otitis media did not have any symptoms revealing an inner ear pathology. Fourteen patients (82.3%) had tinnitus and hearing loss of sensorineural or mixed type, and 10 patients (58.8%) also had vertigo. Tinnitus was constant in all patients (Table 1). Five of 8 patients with chronic otitis media had audiograms that showed a hearing loss of mixed type ipsilateral to JD, and the sensorineural component of the mixed type hearing loss was in the high frequency range in each patient’s audiogram. All of the 5 patients had high-pitched, constant ipsilateral tinnitus. Three of the 5 patients with mixed type hearing loss also had positional vertigo, especially when the head was turned ipsilaterally. Dix-Hallpike testing had negative results in these 3 patients. Of 8 patients with chronic otitis media, 3 with ipsilateral JD had moderate conductive hearing loss. None of the 3 patients had vertigo. Six patients had high-pitched, constant tinnitus and progressive sensorineural hearing loss. The audiograms revealed sensorineural hearing loss on the side of JD. Four of 6 patients had downsloping audiograms, whereas 2 patients had flat audiograms. Auditory brainstem response audiometry did not reveal a retrocochlear lesion in any of the 6 patients. Four patients had vertigo of positional type with short duration, which was pronounced with turning of the head or hyperflexing of the neck. Electronystagmographic results were normal in these 4 patients, including Dix-Hallpike testing. Three cases had episodic vertigo, hearing loss, and tinnitus, which suggested endolymphatic hydrops. Two cases were diagnosed with moderate sensorineural hearing loss in audiometry with down-sloping curve. One case had a flat, symmetric audiogram pattern of sensorineural hearing loss. Electronystagmographic results were normal in each case. Results of transtympanic electrocochleography showed summating potential/action potential (SP/AP) ratios of greater than 0.35 on the side of JD in all 3 cases. When the extension of JD with respect to the reference line was evaluated, 6 patients with anterior-extending and 11 patients with posterior-
BILGEN et al
383
Fig 1. CT scan, axial section. Reference line is perpendicular to basal turn of cochlea and tangent to vestibule. C, Cochlea; V, vestibule.
Fig 2. Axial CT scan section shows (A) anterior-extending JD and (B) posterior-extending JD with respect to reference line. Black arrow, JD.
extending JD were identified (Table 2). Three (50%) of the 6 patients with anterior-extending JD
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384 BILGEN et al
Table 1. Clinical and radiologic features of patients. Patient
Age (y)/Gender
Side
Symptom/Finding
Extension of JD
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
36/Female 34/Female 23/Female 37/Female 38/Female 53/Male 41/Male 32/Female 50/Male 49/Male 54/Female 37/Male 47/Female 40/Male 38/Male 42/Male 46/Female
Right Right Left Left Left Left Right Right Left Left Left Right Left Left Left Right Left
SNHL, T, V MHL, T, V MHL, T MHL, T CHL SNHL, T CHL MHL, T, V SNHL, T, V SNHL, T, V(eh) SNHL, T, V CHL SNHL, T, V SNHL, T, V(eh) SNHL, T, V(eh) MHL, T, V SNHL, T
Anterior Anterior Anterior Anterior Anterior Anterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior Posterior
SNHL, Sensorineural hearing loss; MHL, mixed-type hearing loss; CHL, conductive-type hearing loss; T, tinnitus; V, vertigo; eh, endolymphatic hydrops.
Table 2. Symptom of vertigo with respect to extension of JD Extension of JD
Anterior Posterior Total
SNSⴙV
SNSⴚV
2 8 10
3 1 4
No SNS Total
1 2 3
6 11 17
SNS, Sensorineural symptoms; SNS⫹V, sensorineural symptoms with vertigo; SNS⫺V, sensorineural symptoms without vertigo
had symptoms of hearing loss and tinnitus without vertigo. CT scans of 2 of these 3 patients with sensorineural hearing loss and tinnitus showed encroachment of JD on the internal acoustic canal (Fig 3). Two patients (33.3%) had sensorineural hearing loss, tinnitus, and vertigo. One patient (16.6%) had neither sensorineural hearing loss and tinnitus nor vertigo. As for the 11 patients with posterior-extending JD, 8 patients (72.7%) had symptoms of sensorineural hearing loss, tinnitus, and vertigo. One patient (9.09%) noted only sensorineural hearing loss and tinnitus, and 2 cases (18.1%) were symptom-free with regard to sensorineural pathology. In this group of 11 patients, 3 patients with endolymphatic hydrops had CT scans that showed involvement of vestibular aqueduct by JD ipsilaterally (Fig 4).
No surgery was performed for the patients with sensorineural hearing loss, tinnitus, and vertigo of positional type. For 3 patients with endolymphatic hydrops, because they did not have debilitating vertigo and were managed well with medical treatment, neither surgical treatment nor ablative treatment with gentamicin was considered. DISCUSSION The anatomy of the venous system, especially that of jugular fossa, is highly variable.2 When compared with high-riding jugular bulb, a relatively common venous variation, JD is considered to be a rare venous anomaly, projecting toward the petrous apex. In the English-language literature, 21 cases with JD exist at this time.2-9 However, the rarity is questionable. This retrospective study presents 17 new cases identified through the records of 1474 patients with otologic problems and HRCT evaluations. This number compares with that of the literature. Because this disease was rarely reported before HRCT and a significant number of JD are likely asymptomatic, it is considered that the disease is underreported.4 Because magnetic resonance imaging (MRI) is not the method of choice in the diagnosis of a JD and because MRI is almost always the only radiologic technique used in the evaluation of sensorineural symptomatology, many cases of JD are probably
Otolaryngology– Head and Neck Surgery Volume 128 Number 3
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Fig 3. Axial CT scan image shows encroachment of JD (white arrow) on internal acoustic canal (*).
Fig 4. Axial CT scan image shows JD (white arrow) involving expected path of vestibuler aqueduct. Lesion is in close proximity to endolymphatic sac (*).
not diagnosed. On the other hand, the cases are usually discovered at preoperative assessment with CT scan, as in 8 patients (47.05%) with chronic otitis media in this series or as in an individual finding on CT scan examination of the temporal bone. A female-to-male ratio was reported as 3:1.2 This ratio was found to be 1.12:1 in this study. Despite the known dominance of the jugular venous system on the right, left-side involvement is more common.4 A similar situation was found in this study: 11 left-sided and 6 right-sided involvements were identified. The relationship between JD and the clinical symptoms is questionable.2 However, with location in close proximity to the inner ear, this venous anomaly is considered to produce sensorineural symptoms, such as sensorineural hearing loss, tinnitus, and vertigo. These symptoms are related to the size and extension of the JD. Depending on the degree of extension, the cochlea, vestibular aqueducts, endolymphatic sac, posterior semicircular canal, and internal auditory canal can be involved.4 Encroachment of the JD on the internal auditory canal or the posterior semicircular canal results in a sensorineural hearing loss, whereas involvement of the vestibular aqueduct or the endolymphatic sac can produce Meniere’s diseaselike symptoms.10 In this series, sensorineural symptoms with the presence or absence of vertigo have been focused on in relation to the extension of the JD with respect to a reference line, perpendicular to the
basal turn of the cochlea and tangent to the vestibule. It has been noted that sensorineural symptoms with vertigo are generally produced when there is a posterior-extending JD (8/11 cases; 72.7%). On the other hand, an anterior-extending JD will likely cause sensorineural symptoms without vertigo (3/6 cases; 50%). Among these patients with anterior-extending JD, 2 cases (2/6; 33.3%) had sensorineural hearing loss, tinnitus, and vertigo. In consideration of the anterior position of the cochlea with respect to the posteriorly located vestibular labyrinth, these results correlate well in anatomoclinical aspect, despite the limited number of patients for a statistical correlation. As for more objective radiologic evidence, in 2 cases with sensorineural hearing loss and tinnitus, an apparent encroachment of JD on the internal auditory canal was shown. An involvement of the vestibular aqueduct was shown in 3 patients with endolymphatic hydrops. However, there were 3 symptom-free cases (17.6%), 2 with posterior-extending JD and 1 with anterior-extending JD. This situation may agree with the statement that the relationship between JD and clinical symptoms is questionable.2 On the other hand, because many of the cases in the literature and in this study have had progressive clinical symptoms starting in adulthood, an opposing question can be posed of whether JD represents a stable congenital anomaly or a pathologic progressive process that is capable of expanding to cause clinical symptoms. The answer to this question is still unclear, although reports document the growth
Otolaryngology– Head and Neck Surgery March 2003
386 BILGEN et al
of the lesion in a limited number of patients.2,6 For a reliable answer, comparison of follow-up images of the patients included in this series is being considered in a companion future study. A high-resolution bone algorithm CT scan with 1.0 mm-thick or 1.5 mm-thick images is the method of choice for evaluation of the vascular anatomy within the temporal bone. A JD is characterized by its continuity with the jugular bulb, its smooth edges, and the lack of aggressive pattern of bone destruction. The differential diagnosis includes jugular foramen lesions and petrous apex lesions.4 A JD will not typically be evident on standard spin MRI, unless an abnormal flow pattern is present. MRI venography would show these anomalies but is not routinely performed during evaluation of suspected seventh or eighth cranial nerve neoplasms. Because MRI alone is presently the standard method of diagnosis for cerebellopontine angle tumors, unexpected vascular anomalies may not be diagnosed before surgery.2 Patients with Meniere’s disease-like symptoms and CT scan evidence of involvement of the endolymphatic system by JD may benefit from surgical intervention, such as endolymphatic sac decompression. For the patients with sensorineural hearing loss or tinnitus and evidence of internal acoustic canal or posterior semicircular canal dehiscence, a decision for surgery, for instance, mastoidectomy and compression of the venous anomaly, should be made with careful evaluation of risks and benefits in each case.4,10 CONCLUSION JD is not an uncommon anomaly as previously believed. Partly because it is asymptomatic and
partly because it causes sensorineural symptoms, generally evaluated with MRI, which is not the method of choice in diagnosis, JD is probably underdiagnosed. Although a relationship between the extension of JD and clinical symptoms seemed to be identified in this study, the study still lacks of statistical evidence because of the limited number of patients in this series. Finally, the progressive nature of this pathology is still a question to be answered. REFERENCES
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