Sigmoid Sinus Wall Anomalies and Idiopathic Intracranial Hypertension Resulting in Pulsatile

Tinnitus: Spectrum of Imaging Findings

Yafell Serulle, MD, PhD, Kevin Quinn, BS, David Eisenman, MD, Robert Morales, MD and Prashant Raghavan, MBBS

University of Maryland Medical CenterDepartment of Radiology

eEdE - 142

Disclosures

• The authors have no relevant relationships to disclose.

Background• Tinnitus may be categorized as subjective, when it

originates in either the peripheral or central auditory system and is perceived only by the patient, or objective, when it arises from a mechanical somatosound.

• Pulse-synchronous tinnitus (PST) arises from the abnormal self-perception of one’s own vascular flow, and can arise from a number of venous and arterial abnormalities.

• Venous PST is more commonly encountered in clinical practice than arterial PST.

Background cont.• Sigmoid wall anomalies (SWA) are an

increasingly recognized cause of venous PST. SWA include sigmoid sinus thinning, dehiscence, diverticulum and ectasia.

• Both open surgical and endovascular interventions have proven successful in the amelioration of PST in patients with SWA

Purpose• The purpose of this exhibit is to present the

spectrum of imaging findings encountered on CT and MRI exams of patients with pulsatile tinnitus secondary to sigmoid wall anomalies in our institution.

• Findings associated with SWA are also described in idiopathic intracranial hypertension (IIH) prompting speculation that IIH may cause SWA

Case 1: 18-year-old male with right pulsatile tinnitus

Axial post-contrast CT images demonstrate thinning of the right sigmoid plate. Note thenormal appearance of the left sigmoid plate.

Case 2: 34 year-old female with right pulsatile tinnitus

Non-contrast axial CT shows a defect along the right sigmoid plate with a small sigmoid sinus diverticulum protruding through the osseous defect.

Case 2 cont.: 34 year-old female with right pulsatile tinnitus

Post-contrast T1-weighted MRI demonstrates a right sigmoid sinus diverticulum

Case 3: 44 year-old female with left pulsatile tinnitus

Axial CT shows ectatic left sigmoid sinus with thinning of the left sigmoid plate without a focal diverticulum

Case 4: 38 year-old female with right PST. Right sigmoid diverticulum found on CT exam

Axial T2-weighted MRI shows dilated CSF spaces around the optic nerves (red arrows). There is also flattening of the optic discs (orange arrows). These findings are typically seen with IIH.

Case 5: 41 year-old female with right tinnitus. Patient had body mass index (BMI) of 40.

Axial temporal bone CT on bone windows demonstrates dehiscence of the right sigmoid. The median BMI in our patient population with venous PST is high (34.6 kg/ m2)

Cont. Case 5: 41 year-old female with high BMI and right PST.

Sagittal T1-weighted MRI (right) demonstrates an empty sella. Axial T2-weighted MRI demonstrates increased CSF spaces around the optic nerves (right).

Case 6: 38 year-old female with right PST.

Axial CT on bone window demonstrates a small dehiscence of the right sigmoid plate. Postcontrast axial CT demonstrates narrowing of the bilateral transverse sinuses. Patient had BMI of 48 kg/m2.

Findings associated with SWA- Overlap with idiopathic intracranial hypertension (IIH)

• Empty Sella• Dilated optic nerve sheaths• Skull base meningoencephaloceles• Transverse sinus stenosis

• Harvey SH et al.* described demographics of 30 patients with SWA who responded to surgery: mean age 38 years, 92.9% females, average BMI 35.5 Kg/m2. This patient population strongly resembles that of patients with idiopathic intracranial hypertension.

• *Otol Neurotol 2014. 35(1):7-15

Findings associated with SWA- Overlap with idiopathic intracranial hypertension (IIH)

• Association between IIH and pulsatile tinnitus has been recognized for some time, however, precise pathologic mechanism not established

• Transverse sinus stenosis (TSS) may be a cause of both IIH and PST

Transmastoid approach for sigmoid sinus wall repair: Intraoperative findings

(A) Appearance of a right sigmoid sinus diverticulum during transmastoid surgery. Yellow lines: outline of normal sigmoid sinus; Blue oval: diverticulum. (B) Post-reduction of diverticulum. Metal suction tip sitting on the wall of the sigmoid sinus through a hole in the bone after diverticulum reduction. (C) Post-repair of sinus wall. Tissue graft reinforcing the wall of the sigmoid sinus, sitting deep to the bone on the sinus wall, through the hole in the bone. Following this step, the hole itself is repaired with synthetic bone cement (Hydroset) and bone pate made from the patient’s own bone.

Eisenman DJ. Otol Neurotol 2011. 32(7): 1116-9

A B C

Postoperative imaging findings: CT

Axial CT image of the temporal bone on soft tissue window (A) demonstrates relatively hypoattenuating material (arrows) lateral to the hyperattenuating, contrast enhanced sigmoid sinus. (B) On bone windows, hydroset material is identified as sharply demarcated hyperdense material (asterisk) conforming to the size and shape of dehiscence. Bone pate is identified lateral to the hydroset as amorphous ill-defined hyperdensity (arrow).

*

A B

*

Imaging Findings

• Sigmoid wall anomalies include attenuation of the sinus plate, frank dehiscence resulting in exposure of the sinus to the air in the mastoid air cells, diverticula and segmental sigmoid sinus ectasia

• There is a high prevalence of imaging findings associated with intracranial hypertension including empty sella, distended optic nerve sheaths and flattening of the optic discs

• There is high incidence of female sex, obesity and weight gain among these patients. Epidemiologic and imaging data suggest substantial overlap with the idiopathic intracranial hypertension patient population

Treatment• Sigmoid sinus wall reconstruction (SSWR) is now commonly

performed via an extraluminal approach, with a high rate of success

• The goal of the procedure is to provide a smooth reconstructed wall of the sigmoid sinus eliminating audible turbulence and minimizing transmission of mural vibrations through the mastoid air cells

• Postoperative imaging appearance is characteristic and include the presence of rigid and soft materials employed for reconstruction

Summary • The neuroradiologist plays a key role in the evaluation

of pulsatile tinnitus. Careful scrutiny of the sigmoid sinus wall may reveal a spectrum of abnormalities that may result in pulsatile tinnitus.

• If detected, imaging signs that may support a diagnosis of idiopathic intracranial hypertension must be sought.

• Future studies to establish the precise link between IIH and venous PST are necessary.

• Postoperative findings following sigmoid sinus wall repair are characteristic, and it is important for radiologists to be familiar with these findings

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