Diagnosis: Intracranial Hypertension
It is often unclear to clinicians what patients mean when they complain of an ear infection. As such, clinicians must ask detailed questions about the patient's exact symptoms at the time of the infection to understand if the patient's problem is indeed acute otitis media. In our experience, a vast majority of patients who report an ear infection and ear pain don't usually have acute otitis media. Their ear pain is typically related to a headache or temporomandibular joint dysfunction. Occasionally, some patients may have acute otitis externa. Since external ear canal infections usually have symptoms of both significant pain and drainage, it is easier to distinguish this condition from acute otitis media, in which the pain and draining occur consecutively. Acute otitis media usually starts with significant and surging pain. This eventually results in perforation, after which the pain stops and drainage begins.
It is our practice to ask who made the diagnosis of otitis—whether it was an ENT, emergency, urgent care, or primary care physician. In general, acute otitis media is very uncommon in adults, so adult patients with this diagnosis need further investigation.
When a patient presents with a history of meningitis, it is important to know if a culture was obtained at the time of diagnosis. Bacterial meningitis is usually caused by a bacterium called Neisseria meningitides or Streptococcus pneumoniae. The latter is found in the respiratory tract (sinuses, ears, lungs, nasopharynx, etc.). Patients with Streptococcus pneumoniae meningitis almost always have an infection that originated from the ear or sinuses. When addressing this, clinicians must identify the pathway through which Streptococcus reached the meninges. The passage of bacteria between the ears and sinuses can occur via several mechanisms, such as congenital defects between the ear or sinuses and the intracranial cavity, invasion of venules (small veins traversing the intracranial cavity and the ear or sinuses), destruction of the bone separating the intracranial cavity from the ear or sinuses due to an infection (e.g., chronic otitis, cholesteatoma), or destruction of the bone by the dura (such as in encephalocele, intracranial hypertension, and aggressive arachnoid granulations).
The workup of a patient with Streptococcus pneumoniae meningitis includes getting a fine-cut CT scan of the temporal bone and sinuses. It's also useful to obtain scans from when the meningitis was diagnosed as these will help identify the source of the infection. Whether it's from the sinuses or the temporal bone, the source will usually have an active infection that appears as an opacification (fluid) on the CT scan. Patients who undergo workup for meningitis almost always get imaging of the brain at the time of the infection, so the clinician would need to find the source of the meningitis to ensure proper treatment.
In this patient, the CT scan of the temporal bones showed significant thinning of the bone that separates the brain from the temporal bone (Figs. 2 and 3). The recent CT scan of the patient's sinuses was normal. Her right temporal bone showed an area of herniation of the meninges into the mastoid. The left mastoid had some fluid, and the tegmen was thinning. This made it difficult to identify which ear was the source of the meningitis. We therefore obtained the CT scan from the patient's original hospitalization for meningitis as well as her ER records. The review of the CT scan from her ER visit showed that the patient's right ear and left sphenoid sinus were filled with fluid when she had meningitis (Fig. 4). Given the thin bone separating the dura from the mastoid on the right temporal bone and the normal sphenoid sinus on her current CT scan, it was likely that the right ear was the source of the meningitis.
Further workup of the patient revealed intracranial hypertension, which is often seen in overweight women of around 50 years old. This condition is thought to be caused by an increase in the central venous pressure (blood pressure in the veinous sinuses of the brain). The best treatment is weight loss, but patients are usually given medications (e.g., acetazolamide) to control the pressure until they reach the recommended weight. In some cases, a ventriculoperitoneal or lumbarperitoneal shunt is placed to reduce the cerebrospinal fluid pressure.
This patient's treatment requires creating a strong barrier between the mastoid and intracranial cavity and correcting the intracranial hypertension. This procedure can be performed in several ways. The middle cranial fossa approach, wherein a window is created into the skull above the ear, provides the best visualization of the defect. In this procedure, the brain is lifted gently from the temporal bone, under which a tissue flap and a bone or cartilage graft is placed to create a barrier. Multiple tissue layers are commonly used to create enough of a barrier to minimize any chance of repeat infection.
Meningitis is a common presenting symptom of spontaneous cerebrospinal fluid leakage. It causes tremendous inflammation within the meninges, and can sometimes seal a small cerebrospinal fluid leakage. In general, a patient presenting with meningitis needs to have a thorough examination of the ear to rule out any acute otitis media. If acute otitis media is present in someone with meningitis, the middle ear must be drained via myringotomy with or without tube placement. Ideally, a tube should be placed to allow continued drainage of the middle ear and delivery of antibiotics into the middle ear.
A transmastoid approach can also be done to reach the mastoid tegmen defect (Am J Otolaryngol. 2012 Sep-Oct;33(5):556). This approach is advantageous because it does not require a craniotomy like the middle cranial fossa approach and patients can usually go home the day after surgery. Patients with a thin mastoid roof can be at risk of developing intracranial hypertension and would need to be evaluated when there is high suspicion. A history of meningitis can also lead to increased intracranial pressure. This patient presumably had intracranial hypertension, which led to the destruction of the tegmen, through which the meningitis-causing bacteria entered.
BONUS VIDEOS: VISUAL DIAGNOSIS
Read this month's Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient's imaging for yourself.
- Video 1. Coronal (vertical) CT of the right temporal bone showing the defect in the tegmen mastoideum (bone separating the brain from the ear).
- Video 2. Coronal (vertical) CT of the left temporal bone showing the thinning of the tegmen mastoideum.
- Video 3. Axial CT of the temporal bones showing no defect in the posterior fossa plate that separates the cerebellum and the mastoid.
- Video 4. Coronal T1-weighted post-contrast MRI of the temporal bones showing the brain close to the destruction of the tegmen above the ear canal on the patient's right side (left side of images).
- Video 5. Axial CT of the brain when the patient had meningitis showing fluid in the mastoid on the right side (left side of images).
- Video 6. Axial T2-weighted MRI of the brain showing fluid in the right mastoid (left side of images) at the time of the meningitis.
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