We saw the patient next 2 1/2 years after her initial appointment.  The history in the intervening time is a bit unclear. Some history was relayed by her audiologist friend, some obtained from the patient.

Her dizziness continued. She continued to receive vestibular rehabilitation which helped somewhat.  As her condition deteriorated she became ataxic.  She walked unsteadily with a wide spaced gate.  Nausea and vomiting increased  Her friend noted exopthalmia and a new consult at another major medical center was obtained.

Another MRI was obtained, two years after the initial one that was reported as negative.  Medulloblastoma, a malignant brainstem tumor, was found in the cerebellum near the 4th ventricle.  The tumor has metastasized.

• How does the diagnosis explain the exopthalmia?
• How common is medulloblastoma?  How rapidly does it grow?
• Does that explain her >2.5 year history of dizziness?

She has had surgical debulking of the tumor and radiation to shrink it. There was a burn on the right pinna from the radiation. The ear canals were swollen. Her tinnitus was worse, she rates it 8-9/10 for high pitch and for loudness.

She is now seen for  baseline testing before receiving chemotherapy.  The report states:

“Tympanometry was conducted to assess middle ear function. The tympanogram was within normal limits for the right ear and indicated a wide slope gradient for the left ear, usually associated with middle ear pathology. However, the presence of acoustic reflexes and no air-bone gaps present on the audiometric results does not substantiate this finding. Acoustic immittance measures indicate normal ear canal volume, static complaince and peak pressure for each middle ear system.

Uncrossed and crossed acoustic stapedial reflexes were eleveated for each ear; however, high artifact levels during testing was noted. Acoustic reflex decay findings are largely uninterpretable. The amplitude of the reflex fluctuated in the first 5 seconds and/or the amplitude of the reflex at 10 seconds appeared unattenuated; however, after signal offset the return to baseline amplitude was reduced, suggesting possible decay.”

• Interpret the statement above.  How could this reflex potentially indicate the presence of decay?

The report continues “DPOAEs . . . were present in each ear at 1000-2000 Hz (only).”

The audiogram is shown below.

• Were the OAE findings as characterized as expected?
• Has hearing changed in the past 2.5 years?
• Next look closely at the OAE actual results (only the right ear is shown, the left was similar). The finding of an emission at 8000 Hz was repeatable and improbable.  We have a hearing impaired student, and her OAEs were also present.  Next, a 2 cc hearing aid coupler was “tested” and it too had an 8 kHz “emission.”  The system was sent for repair.

 

 

 

 

 

 

 

 

 

Hearing thresholds through 14 kHz were obtained as well to aid in monitoring hearing during chemotherapy treatment.

Spondee thresholds were 20 dB HL AD, 25 dB HL AS. Word recognition scores were 100% at 60 dB HL in each ear.

Because she may need retesting when not feeling up to participating in behavioral testing, and because OAE data is so limited, we also did ABR testing. Click evoked potentials were obtained partly to answer our own clinical question – were the auditory pathways affected by this tumor?   The ECoG previously administered did not reveal any suggestion of prolonged neural conduction times but the use of the horizontal montage made it difficult to interpret.

• Interpret the click ABRs.

The NSU summary form may be useful.

NSU Auditory Brainstem Response Report Summary

 

 

Tone burst 2k Hz (5 ms duration stimulus) ABRs were obtained at 60 and 80 dB nHL left and just 80 dB nHL right, which also could be used in monitoring for hearing changes.

• What do you think of the choice of 2k as the stimulus?

We additionally wanted some vestibular baseline information.  The Snellen chart was used to evaluate visual acuity with and without headshake. The patient’s ability to read was reduced by two lines during horizontal headshake.  Halmagyi head thrust was conducted in both left and right directions; there were no catch-up saccades.

• Why was this testing done, and why not assess the patient’s abilities standing on foam?