<div>A case of jugular bulb diverticulum causing objective tinnitus</div><div>Ichiro Fukumoto, Kazuki Yamasaki, Shuji Yonekura, Tomohisa Iinuma,
Yukiyoshi Mita, Yuri Sonobe, Toyoyuki Hanazawa</div><div>Department of Otorhinolaryngology/Head and Neck Surgery, Chiba
University Graduate School of Medicine</div><div>Corresponding author: Ichiro Fukumoto</div><div>E-mail address: ichiro_ichiro_1124@yahoo.co.jp</div><div>Key clinical message</div><div>If we suspect vascular objective tinnitus from a medical interview, we
should check for jugular bulb diverticulum and cortical bone defects on
temporal bone CT, in addition to thorough physical examination and
contrast-enhanced imaging.</div><div>Abstract</div><div>Anatomical anomalies of the jugular bulb include a high jugular bulb and
deficiency of the cortical bone. Most cases are asymptomatic; however,
they may present with tinnitus, hearing loss, dizziness. We encountered
a rare case of jugular bulb diverticulum with deficiency of the cortical
bone that caused objective tinnitus.</div><div>Key words</div><div>High jugular bulb, Jugular bulb diverticulum, Objective tinnitus</div><div>Introduction</div><div>The jugular bulb is the vein structure of the posterior fossa that is
formed when the sigmoid sinus shifts to the internal jugular vein of the
jugular foramen <sup>1</sup>. It is generally divided between the
cortical bone with the tympanic cavity and the mastoid cavity.
Anatomical anomalies of the jugular bulb include a high jugular bulb
(HJB), which exists in the middle ear cavity across the bottom end of
the tympanic ring, and a dehiscent high jugular bulb (DHJB), which is
deficient in the cortical bone. The prevalence of HJB is 6%, and there
are more cases of HJB and DHJB on the right side than on the left. It is
often asymptomatic; however, it can sometimes cause hearing loss,
pulsatile tinnitus, dizziness, vertigo <sup>2</sup>, and repeated
facial paralysis <sup>3</sup>. During surgery of the middle ear
and lateral skull base, it is critical to confirm an HJB preoperatively.
Moreover, the bleeding must be assessed when the jugular vein is damaged<sup>4</sup>.</div><div>An HJB is common; however, a jugular bulb diverticulum is rare. The
projection direction of the jugular diverticulum varies, including the
middle ear cavity, mastoid cavity, and inside apex of the petrous bone<sup>5</sup>.</div><div>Tinnitus is a phenomenon that produces sound perception even when there
is no external sound. In most cases, the sound is subjective tinnitus,
which does not exist in the body, but the sound is objective tinnitus,
which is partly present in the body. Objective tinnitus can be in the
form of muscular scoliosis or be vascular in nature; however, there are
few reports of objective tinnitus. We encountered a case of an HJB
diverticulum that caused objective tinnitus.</div><div>Case history</div><div>A 30-year-old man presented to our hospital with a chief complaint of
intermittent right tinnitus persisting for 2 months. His medical history
included hypertension, dyslipidemia, and fatty liver disease. Tinnitus
was vascular pulsatile with a rushing sound; it began suddenly and
showed improvement in the cervical position. In addition, tinnitus was
exacerbated on the day when the patient forgot to take his
antihypertensive medications.</div><div>The eardrum was normal and a carotid run abnormality or HJB was not
suspected on eardrum examination. Although the patient had slight right
vascular pulsatile tinnitus during the hospital visit, we could not
detect objective tinnitus using an otoscope. The tinnitus disappeared
when the internal jugular vein was pressed from the cervical skin. The
audiometric test results were normal, and objective tinnitus was
suspected based on the anatomic abnormalities in the temporal bone,
including angiectopia, after interviewing the patient.</div><div>Jugular vein diverticulum was detected on the computed tomography (CT)
scan of the cephalad side, and the efficiency of the cortical bone was
detected in the mastoid sidewall of the diverticulum (Figure 1).
Neoplastic lesions, such as glomus tumors, were absent on enhanced
magnetic resonance (MR)imaging. In addition, there was no evidence of
cerebral aneurysm, cerebral arteriovenous malformation, or brain
arteriovenous fistulas on MR angiography(Figure 2). In MR venography
(MRV), there was obstruction of the left transverse sinus, and
hypoplasia was found from the left sigmoid sinus to the internal jugular
vein (Figure 3). The occipital sinus developed, and it flowed into the
right sigmoid sinus; consequently, the right jugular vein had
significantly more return in quantity (Figure 4).</div><div>We suggested to the patients about surgical and endovascular treatment;
however, he did not hope it and became the policy of the follow-up.</div><div>Discussion</div><div>The main causes of objective tinnitus are the muscle and blood vessels.
The muscular mechanism includes activities of the tensor veli palatini,
levator veli palatini, tensor tympani <sup>6</sup>, stapedius,
salpingopharyngeus, and superior constrictor muscle of the pharynx. The
vascular mechanism is divided into arteriosity and phleboid<sup>7</sup>. The arteriosity causes include are abnormalities of
the internal carotid artery, carotid hardening-related lesions,
aneurysms, arteriovenous malformations, and dural arteriovenous fistulas<sup>8</sup>. The phleboid causes include HJBs, glomus tumors,
and middle ear tumors <sup>9</sup>.</div><div>It is comparatively simple to determine whether the causes of objective
tinnitus are myogenic or vascular by conducting interviews and examining
the properties of the sound. If the causes are suspected to be vascular,
it should be confirmed whether there are changes in the tinnitus on
pressing the internal jugular vein from the neck skin and by judging the
arteriosity mechanisms or characteristics of the vein. The anatomical
anomaly should be examined using temporal bone CT in all patients with
objective tinnitus. When tinnitus is suspected from the vasculature, MRA
or MRV should also be performed.</div><div>The jugular bulb is located post lateral to the jugular foramen and
receives drainage from the intracranial and extracranial parts. The
sigmoid and inferior petrosal sinuses flow into the jugular bulb and
form the internal jugular vein.</div><div><sup>10</sup>.</div><div>Anatomic abnormalities of the jugular bulb include an HJB, deficiency of
the cortical bone, and jugular bulb diverticulum; however, they are
often asymptomatic. Nevertheless, it has been reported that an HJB and
deficiency of the cortical bone cause vascular tinnitus<sup>11</sup>, sensorineural hearing loss, facial paralysis,
vertigo, and dizziness. Moreover, they can cause Meniere’s disease and
endolymphatic hydrops <sup>12</sup>.</div><div>In this case, it was difficult to prove that the cause of vascular
tinnitus was the turbulence of flow in the jugular bulb diverticulum.
However, it was more likely to be vascular tinnitus, in addition to
phleboid tinnitus, when we assume that tinnitus is improved by pressing
the internal jugular vein from the neck and changing the cervical
position. Moreover, tinnitus may occur owing to jugular bulb
diverticulum when the deficiency of the cortical bone is considered,
along with the right venous return being completely dominant in MRV, and
multiple blood vessels flowing to the jugular bulb; there are no
neoplastic lesions reported previously <sup>13</sup>.</div><div>Although the jugular diverticulum was present previously, the cause of
its sudden occurrence at 30 years of age may be attributed to the change
in the blood flow of the venation. There is no contradiction that
regression of the blood flow, such as the left transverse sinuses,
increased the right blood flow, causing turbulence in the jugular bulb.
We measured D-dimer in consideration of thrombus as decreased blood flow
in the left vein was within the normal range. This patient had a past
medical history of juvenile hypertension and was diagnosed with phleboid
tinnitus according to a previous report <sup>1</sup>. As tinnitus
was aggravated when the antihypertensive medications were not taken,
hypertension can be considered one of the factors of sudden onset.</div><div>Although surgical therapy and endovascular treatment was recommended for
this patient, he did not agree to the treatment as he was aware that the
tinnitus was because of the jugular bulb and there were no aneurysms or
tumors. There is no established treatment for objective tinnitus caused
by jugular bulb anatomical anomaly.</div><div>It has been reported that improvement can be achieved by placing bone
wax in the cortical bone deficiency by surgery <sup>14</sup>.
Another study reported that improvement of the vascular tinnitus was
detected after surgery <sup>15</sup>. However, surgery or
endovascular treatment cannot be considered a definitive treatment.
Surgery should be considered in patients with severe tinnitus impairing
everyday life, persistent vertigo, and progressive sensorineural hearing
loss <sup>16</sup>.</div><div>Conclusion</div><div>We reported a case of jugular bulb diverticulum that caused objective
tinnitus. The jugular diverticulum and cortical bone deficiency must be
confirmed using temporal bone CT when vascular objective tinnitus is
suspected from an interview. It was assumed that the right venous return
was significantly associated with tinnitus based on MRV.</div><div>Acknowledgments</div><div>The authors would like to thank MD/PhD Yoichi Yoshida for his advice on
this manuscript from the viewpoint of a neurosurgeon.</div><div>Conflict of Interest</div><div>The authors declare no conflicts of interest.</div><div>Author contribution</div><div>Ichiro Fukumoto: Drafting of this article</div><div>Kazuki Yamasaki: Revision of this article</div><div>Shuji Yonekura: Revision of this article</div><div>Tomohisa Iinuma: Revision of this article</div><div>Yukiyoshi Mita: Collecting clinical information</div><div>Yuri Sonobe: Collecting clinical information</div><div>Toyoyuki Hanazawa: Final approval of this article</div><div>Reference</div><div>1. Manjila S, Bazil T, Kay M, Udayasankar UK, Semaan M. 2018. Jugular
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Audiol</i> . 16(1):39-42.</div><div>Figure Legends</div><div>Figure 1</div><div>In the temporal bone computed tomography (CT), the jugular bulb
diverticulum that goes above is present on the right side, and the
cortical bone is deficient on the sigmoid side; however, extension to
the middle ear alveus is not detected. In addition, a shadow suspected
as a glomus tumor is absent.</div><div>Figure 2</div><div>The cerebral aneurysm, cerebral arteriovenous malformation, and brain
arteriovenous fistulas are not found in the magnetic resonance
angiography (MRA).</div><div>Figure 3</div><div>In magnetic resonance venography (MRV), the left side transverse sinus,
sigmoid sinus, jugular bulb, and internal jugular vein are not depicted.
The venous return has clear laterality.</div><div>Figure 4</div><div>In magnetic resonance venography (MRV), the right occipital sinus is
developed, and flows into the right jugular bulb. The right jugular bulb
was considered to have many venous returns in quantity.</div>