Article
Evaluation of inner ear function before and after diagnostic large volume CSF removal in normal pressure hydrocephalus patients
Die Entnahme größerer Liquormengen und der Einfluss auf die Innenohrfunktion
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Published: | April 23, 2004 |
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Outline
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Objective
Diagnostic removal of cerebrospinal fluid (CSF) via lumbar puncture or drainage is a routine procedure in patients with suspected normal pressure hydrocephalus (NPH). Large volume CSF removal, however, may result in hearing loss. We have shown previously that there is no change in pure tone and speech audiometry after diagnostic CSF removal in NPH patients. In this study, inner ear function was assessed by additional objective examinations.
Methods
In this prospective study, 55 consecutive patients with suspected NPH underwent diagnostic large volume CSF removal via lumbar puncture or lumbar drainage. All patients underwent a test battery including pure tone audiometry, speech audiometry for total word comprehension (mono syllables) and number comprehension, tympanometry, threshold of stapedius reflex, evoked otoacoustic emissions, nystagmogram and acoustic evoked potentials before and after CSF removal to investigate its short-term effect on inner ear function. A significant difference in the hearing levels was presumed if the normal individual range of 10 dB in tone audiometry or 10% in speech audiometry was exceeded. Patients were reexamined within the first three days after CSF removal.
Results
There were no complications related to large volume CSF removal. In pure tone audiometry, some patients had hearing loss or showed improvement of hearing in more than four frequencies tested. This correlated neither with the method of CSF removal (LP vs. Touhy drainage) nor with a cognitive change due to the CSF removal. Tympanometry, threshold of stapedius reflex and evoked otoacoustic emissions showed no differences before and after CSF removal. The results of these examinations supported the findings of audiometry. Nystagmograms were unremarkable after CSF drainage. The acoustic evoked potentials showed no significant differences in amplitudes, latencies or inter-peek-latencies.
Conclusions
Diagnostic large volume CSF removal by lumbar puncture or by lumbar drainage appears to be relatively safe concerning inner ear function in patients with suspected NPH.