This schwannoma grows at the expense of the Schwann sheath of the vestibular nerve in the IAC (Internal auditory canal) at the Scarpa’s ganglion.
The questions and answer session indicates that there is an imbalance (swerving motion while walking). Said imbalance becomes more acute in the dark and can appear if the head is moved quickly.
It will be noted that this symptomatology resembles, although mistakenly, the medium and log term consequences of a badly re-educated SUVD.
Differential diagnosis is nevertheless simple; there has never been major initial vertigo lasting a number of days.
There are homolateral acoustic signs: hearing loss (and not presbyacussis) and comprehension issues (on the telephone ...).
The examination will show:
1 – unilateral perceptive deafness often associated with bad speech comprehension
2 – sometimes a slight horizontal spontaneous nystagmus using VNS / VNG
3 – a homolateral hyperreflexia most often than not compensated
4 – an AEP (Auditory Evoked Potential) with elongation of the range I-V or a disruption to the alignment.
Diagnosis can be confirmed by MRI (Magnetic Resonance Imaging) (weighted T1 or T2 images with Gadolinium - Gd - in I.V.) focused on the IAC, the vestibular nerve and the central and posterior structures.
Evolution: the development of the tumour in the cerebellopontine angle will cause central vestibular signs to appear:
- vertical or multidirectional perverted nystagmus,
- too weak an OFI (Ocular Fixation Index),
- a saccadic pursuit eye movement,
- saccadic dysmetria (with overshooting) with saccadic eye movement upon refocusing.
Acoustic neuroma is treated using surgery. The translabyrinthic is the chosen approach. Only this approach will avoid scarring of the cerebellum.
Respectively, the subpetrous approach should be used when the tumour is IAC and the retrosigmoid approach when the tumour is located at the cerebellopontine angle, as these will allow us to try to save homolateral hearing (socially useful) when it is essential.
Even if equilibration problems generally diminish after surgery, vestibular reeducation is essential, especially in cases where pre-operative areflexia is incomplete.
Often HF will be put to good use to "subdue" the system in pre-op, having consulted with the surgeon.
In post-op, customising rehabilitation will take precedence over all other “fixed” protocol.