BPPV of the Lateral Semicircular Canal (LSC)
In the BPPV of the LSC there is also a GEOTROPIC FORM, which represents 70-75% of cases, and an APO-GEOTROPIC FORM, for the remaining 25-30%.
Prof. Nuti’s classification foresees 5 forms.
NUTI’S CLASSIFICATION OF BPPV
- APO-GEOTROPIC CHANGING INTO GEOTROPIC
- PURE APO-GEOTROPIC (Remains such until its disappearance)
- GEOTROPIC THAT BECOMES BPPV OF THE PSC
- BPPV OF THE PSC THAT BECOMES BPPV OF THE LSC
Obviously, for each form, the appropriate treatment is dealt with within each specific chapter. For this reason, the main emphasis here is given to the individual geotropic and apo-geotropic forms.
For diagnostic purposes, the PAGNINI-MCLURE MANOEUVRE is very important.
PAGNINI –MCLURE MANOEUVRE
Otherwise known as the supine head rotation test, it is as much a diagnostic as therapeutic manoeuvre. The patient is placed in a supine position lying on the examination table, and a 180° head rotation is performed on both sides.
Diagnostic characteristics of the LSC BPPV
The rapid phase of the nystagmus appears as purely horizontal, beating downwards in the GEOTROPIC FORM and upwards in the APO-GEOTROPIC FORM, when positioned towards the affected side. Reversal of the nystagmus during the maintenance of the reactive position is not uncommon. Presenting paroxysm and a long duration, as it can easily reach over a minute, and very short latency (2 seconds), or even latency-free. Nystagmus of the LSC BPPV is certainly less extinguishable than others, especially in the PSC.
In the treatments of the LSC BPPV the Gufoni Manoeuvre is certainly very important. In the geotropic form, this requires the patient to be brought rapidly from the sitting position into a side-lying position towards the unaffected side and, always with a quick movement and towards the unaffected side, rotate the patient’s head by 45° towards the table. The position is held for a couple of minutes and then the patient is returned into a straight sitting position.
In the apo-geotropic form, the patient is rapidly moved to the affected side and the head is rotated by 45° towards the unaffected side. In this way two different results can be achieved. Firstly, the freeing of the canal, secondly, the transformation of the form from apo-geotropic into geotropic, which subsequently allows to perform the Gufoni manoeuvre.