Temporal bone venous anomaly of surgical significance

Large Jugular Bulb Diverticulum Invading the Internal Auditory Canal

Objectives:

We report, with neuro-otologic findings, a very rare case of a large jugular bulb diverticulum eroding the internal auditory canal (IAC).

Methods:

We present the imaging and functional studies of a 29-year-old woman in whom a large jugular bulb diverticulum on the left side was found incidentally.

Results:

Imaging studies revealed a normal external auditory canal, middle ear, and inner ear, but a large jugular bulb diverticulum extending superiorly on the left side had eroded the IAC from below and behind with destruction of the petrous bone. Caloric responses and facial movements were normal. Vestibular evoked myogenic potentials with bone conduction stimuli were absent on the left, indicating dysfunction of the left inferior vestibular system.

Conclusions:

This is the first report in the English-language literature of detailed imaging and functional findings in a very large diverticulum invading the IAC. Vestibular evoked myogenic potentials were useful in uncovering subclinical inferior vestibular system dysfunction in the jugular bulb diverticulum invading the IAC.

An anatomical and radiological study of the high jugular bulb on high-resolution CT scans and alcohol-fixed skulls of adults

Although many reports mention a "high jugular bulb" (HJB), it is often not clearly defined. We examined the relationship between the jugular bulb (JB) and the internal auditory canal (IAC) in 200 temporal bones on high resolution CT scans and alcohol-fixed skull bases of adults. The average distance (+/-standard deviation) between the IAC and the JB was 7.5+/-2.3mm (range, 1-16 mm). The JB was higher on the right side than its companion in 53.3% of patients (left side only in 22%; no side dominance in 23.7% of bases). When the JB reached or exceeded the floor of the IAC (16.5%), it was defined as a HJB; 61% of HJB were found in females. Bilateral HJB was found in 0.5% of patients. The HJB was not associated with a contralateral flat JB. Preoperative multiplanar high resolution CT reconstructions make the most detailed assessment of structural topography.

High jugular bulb in the translabyrinthine approach to the cerebellopontine angle: anatomical considerations and surgical management

BACKGROUND

Evidence of a high jugular bulb position (HJBP) during the translabyrinthine approach may compromise the surgical removal of cerebellopontine angle (CPA) tumours. We report a simple surgical procedure to safely manage this frequent normal variation and comment on various alternative options.

METHODS

The translabyrinthine approach included a complete skeletonization of the sigmoid sinus and of the presigmoid dura. A thin eggshell bone was left at the jugular bulb surface. The dome of the jugular bulb was gently dissected from the jugular fossa and gradually retracted downward in a tailored way, allowing the surgeon to drill below the internal auditory meatus. A small piece of bone was wedged over the jugular dome in order to maintain its lowered position.

RESULTS

Among 178 consecutive translabyrinthine approaches performed for the removal of large CPA tumors, the use of this procedure was required in 44 cases of HJBP. Excepting minimal venous bleeding easily controlled in several cases, we never observed any complication from this procedure nor failure to expose the inferior compartment of the CPA.

CONCLUSIONS

The HJBP can be systematically diagnosed with the preoperative CT-scan using bone window imaging. Our results demonstrate that the described procedure is safe and effective to widen the operative corridor that is required for the exposure of the inferior compartment of the CPA in this anatomical situation.

Vascular anomalies, sutures and small canals of the temporal bone on axial CT

PURPOSE

Subtle bony structures, small canals and fine sutures cause sometimes problems in the analysis of CTs of the temporal bone. The aim of this study was: to analyze the visibility of subtle structures and to estimate the incidence of vascular anomalies.

PATIENTS AND METHOD

We retrospectively analyzed axial scans of 223 high-resolution CTs of the temporal bone obtained as single slice or spiral CT with 1mm slice thickness. All CTs had clinical indications. Two experienced radiologists studied CTs regarding the visibility of the fine sutures, fissures and small canals and the occurrence of vascular anomalies.

RESULTS

The following structures were seen commonly: sphenosquamosal suture (76%), arcuate artery canal (93%), vestibular aqueduct (89%), mastoid emissary vein (82%), singular canal (56%). Not so commonly were observed: tympanosquamosal suture (31%), mastoid canaliculus (28%), lateral sigmoid sinus (28%), petrotympanic fissure (24%), tympanomastoid suture (10%). Seldom we identified: the inferior tympanic canaliculus (6%), high jugular bulb (6%), anterior sigmoid sinus (5%), dehiscent internal carotid artery canal (2%), persistent petrosquamosal sinus (1%), dehiscent jugular bulb (1%). Persistent stapedial artery, aberrant internal carotid artery, dehiscent jugular bulb, high jugular bulb with diverticulum, anterior and dehiscent sigmoid sinus were detected in below 1% of the analyzed temporal bones. The frequency of asymmetry of the jugular foramen, which varied between 3% and 42%, depended on different criterions of size.

CONCLUSION

A profound knowledge of normal anatomy and anomalies of the temporal bone avoids misinterpretation as pathological lesions and iatrogenic bleedings.

Jugular bulb diverticula: clinical and radiologic aspects

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.

Aberrant jugular bulb vein obstructing approach to intracanalicular vestibular schwannoma

In cases of jugular bulb anomalies, such as a high jugular bulb, troublesome bleeding may occur during surgery. We report an unusual case with a vestibular schwannoma, in which we recognized an additional branch arising from the jugular bulb. Three-dimensional computed tomography (3-D CT) revealed this anomaly beforehand, enabling us to avert excessive bleeding upon resection of the tumour. The abnormal vein was thought to be a remnant of the petrosquamosal sinus in the embryonic stage.

Computed tomographic evaluation of surgically significant vascular variations related with the temporal bone

Variations of the vascular structures related with the temporal bone may cause important problems in diagnosis, treatment planning and surgery. High resolution computed tomography (CT) scans of 700 temporal bones of 350 patients were retrospectively examined for the incidence of dehiscent jugular bulb, high jugular bulb, diverticulum of jugular bulb, anteriorly located sigmoid sinus and dehiscent internal carotid artery. Dehiscent jugular bulb was seen in 27 (3.9%), high jugular bulb was seen in 142 (20.3%), jugular bulb diverticulum was seen in 55 cases (7.9%). The average distance between external acoustic canal and sigmoid sinus was found to be 13.3 mm and in 12.4% of the cases this distance was < 10 mm. Of 700 temporal bones, 10 (1.4%) showed dehiscent carotid canal. To aid diagnosis, treatment planning and surgery, CT scanning is currently a very reliable tool in determining these conditions. Special attention should be paid to the position of the vascular structures in the preoperative temporal bone CT scans.

The high jugular bulb in ear surgery: three case reports and a review of the literature

Encounters with the jugular bulb in ear surgery are uncommon. This communication relates three cases where the author was confronted with the bulb in middle ear surgery--one in relation to the external auditory canal when raising a tympanomeatal flap and two in the hypotympanum when entering the middle ear. The anatomy of the jugular bulb is considered, particularly in regard to its quite variable placement within the temporal bone. The manner of clinical presentation of the high jugular bulb and previous cases in the literature where the jugular bulb has been discovered in juxtaposition to the surgical approach are discussed. Implications of surgical management are considered.

Petrous jugular malposition (diverticulum)

Jugular bulb anatomy is variable. A "high-riding" bulb extending into the tympanic cavity is a well-described anomaly. Petrous jugular malposition (diverticulum) (PJMD), however, is rare. The relationship between PJMD and clinical symptoms is questionable because the differentiation between PJMD as an anatomic variant and pathologic process is unproved. A literature review reveals 14 previously documented cases. We report an additional four cases. Diagnostic and management dilemmas are discussed, with the importance of high-resolution CT stressed.