Dear Professor Chiesa,Thank you for offering us the possibility to reply to the
Letter to the Editor and we also thank Dr. Asprella Libonati
for the interest shown in our article Converting apogeotropic
into geotropic lateral canalolithiasis by headpitching
manoeuvre in the sitting position which was
recently published in Acta Otorhinolaryngologica Italica.
I fully agree with Dr. Asprella Libonati’s comments concerning
the need to offer (if possible, I would add) a theory
related to the phenomena observed in lateral canalolithiasis,
a concept which is, in fact, expressed also in
our article: "The pathophysiology of Pseudospontaneous
Nystagmus (Fig. 1), Bow and Lean Nystagmus (Figs. 2,
3), Positioning Nystagmus from sitting to supine position
(Fig. 4) and the transformation from apogeotropic to geotropic
canalolithiasis, are in keeping with the theory of
canalolithiasis … They (Otoliths) move as if they are on
an inclined plane and their movement provokes the Bow
Nystagmus towards the healthy side, and the Pseudospontaneous
Nystagmus, the Lean Nystagmus and the Positioning
Nystagmus from the sitting to the supine position
towards the affected side".As can be seen, we mentioned and evaluated, the mechanism
of the inclined level, moreover, not neglecting, in our
article, to quite rightly refer to (including also the titles in
the list of References) the important work performed by
Dr. Asprella Libonati in this particular field.We also agree with his having pointed out the various
modes and the meaning of diagnostic "Head-Pitching"
(Head-Pitching Test) compared with the therapeutic aspects
(Head-Pitching Manoeuvre), both as far as concerns
the meaning from a terminology viewpoint but also from
a practical point of view, indeed the title of our article
refers to the "head-pitching manoeuvre".On the other hand, we do not completely agree with the
proposal to combine, in a single definition "pseudospontaneous
nystagmus", all the types of non-paroxystic nystagmus
observed in lateral canalolithiasis.This for two reasons:The forms of nystagmus defined as "Bowing (or Bending)
Nystagmus", "Leaning Nystagmus" and "Sitting
to supine positioning Nystagmus (or Lying-down nystagmus)"
may be present also in the absence of "Pseudospontaneous
Nystagmus" thus as defined by Dr.
Asprella Libonati, with the patient in a sitting position
with his/her head straight and aligned with the body.
In my opinion, therefore, these signs are autonomous,
also as far as concerns the unifying theory of canalolithiasis
and of the otolithic movement on an inclined
level resulting from, on the one hand, the initial position
of the otoliths in the canal and, on the other, the
positioning of the head, and consequently of the canal,
in the planes of the space.These forms of nystagmus have been described in the
Literature and, therefore, with due respect to those
Authors who proposed them, they should be correctly
cited, when reference is made to them.In closing, just one last observation. Reading between
the lines of the article, it was our intention, to point out
the possibility of the conversion from lateral apogeotropic
canalolithiasis to the geotropic form by means of the
Head-Pitching manoeuvre, not so much for its effective
practical usefulness (other manoeuvres, in our opinion,
in particular the first step of Gufoni’s therapeutic manoeuvre
towards the affected side, are more efficacious
for this purpose), but inasmuch as it represents, as far as
concerns the lateral apogeotrope forms, further confirmation
of its usefulness, at least in the majority of cases, of
the pathogenetic interpretation, held by Italian Authors, of
the "free-"oating otoliths" in the ampullar arm, compared
to that of the "cupula-adherent otoliths", preferred, on the
other hand, by authoritative foreign Authors.In other words, our intention was to offer a further contribution,
by means of a description of a phenomenon,
which had, so far, not been reported, to that hypothesis
of the otolithic sliding along a sloping plane being a moment
which determined the endolymphatic currents responsible
for the excitatory or inhibitory canalar stimuli
which trigger the paroxistic and non-paroxistic nystagmic
ocular movements characteristic of lateral canalolithiasis.With kindest regards,Luigi Califano