Otogenic Lateral Sinus Thrombosis Workup

Updated: Mar 21, 2019
  • Author: B Viswanatha, DO, MBBS, PhD, MS, FACS, FRCS(Glasg); Chief Editor: Arlen D Meyers, MD, MBA  more...
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Laboratory Studies

The following laboratory studies are indicated:

  • Culture and sensitivity of purulent material

  • CBC count and differential count

  • Blood culture

The antibiotic era has seen a change in not only the clinical presentation of lateral sinus thrombosis but also bacteriology. This change in bacteriology is thought to be due to the fact that the disease more commonly proceeds by chronic rather than acute ear infection. Beta hemolytic streptococcus is no longer a dominant organism. Since chronic, rather than acute, infection more commonly precedes lateral sinus thrombosis, cultures characteristically yield mixed flora, including Bacteroides, Staphylococcus, Enterobacteriaceae, Proteus, Pseudomonas, and other species. Because antibiotics are commonly used during the prodromal ear infection, blood culture is often negative.


Imaging Studies

Imaging studies have been considered diagnostic aids for lateral sinus thrombosis, and definitive diagnosis can be made at surgery. Present imaging techniques and experiences enable clinicians to have relatively precise view of lateral sinus thrombosis before surgeries.

CT is particularly important for demonstrating pathology in the mastoid and cranial cavity and excluding existing intracranial complication. CT scanning with contrast can demonstrate a filling defect in thrombosed sinus and ring enhancement or the “delta sign” around the thrombosed sigmoid sinus. CT scan usually demonstrates the "delta sign," an empty triangle at the level of sigmoid sinus that consists of a clot surrounded by a high-intensity rim of contrast-enhanced dura, when thrombus is present. However, this sign is not always detectable and not all thrombus can be demonstrated by CT scanning.

MRI is more sensitive than CT scanning in detecting the thrombus. It shows blood flow, sinus obstruction, and the subsequent reversal of flow. On gadolinium-enhanced MRI, thrombus appears as soft tissue signal associated with vascular bright appearance of the dural wall (the "delta" sign, as seen with gadolinium enhanced MRI). This is the investigation of choice and should be performed in conjunction with CT scanning, thereby fully evaluating the associated otologic and cerebral pathology.

With the presence of significant sinus thrombosis, an MRI and magnetic resonance venogram (MRV) are warranted, because they can be used serially for clot progression and resolution.


Other Tests