BPPV of the Anterior Semicircular Canal (ASC)
BPPV of the ASC generally shows in videoculonystagmoscopy with a positional down-beating nystagmus with rotation towards the affected side, where a torsional component also directed towards the pathological side can be associated, albeit infrequently. Often, it is precisely this torsional component that allows a clearer identification of the affected side. ASC nystagmus is to be found mainly by means of a videoculonystagmoscopy with the Dix-Hallpike manoeuvre and head hanging position. Nystagmus in ASC canalolithiasis has an average latency of 2 seconds, therefore inferior to that of the posterior semicircular canal, and a duration that can range from a few seconds to over sixty-ninety seconds. Its paroxysm may not be particularly marked because of its initial brief increasing trend, and the slow decrease with non-constant stress.
The repositioning of the ASC otolith can be carried out by means of a variety of manoeuvres. Here listed are some particularly useful ones:
Reverse Epley manoeuvre
Modified Semont manoeuvre
In the reverse Epley manoeuvre, the most applied at Vestibology medical, the patient is placed in the Dix-Hallpike position on the healthy side, and the head is rotated very slowly towards the pathological side. Once in the counter-lateral Dix-Hallpike position, the patient is rotated on the affected side, with a further 90° downward rotation of the head. The patient remains in this position for a few seconds and then is brought back to a sitting position to favour the outflow of debris from the ASC.
A variant of the reverse Epley manoeuvre:
- The patient sits on the examination table
- rotates the head by 45° towards the healthy side
- The patient is kept in the Dix-Hallpike position for at least 2 minutes
- the patient’s head is placed in the supine position while maintaining a 45° rotation towards the affected side
- holding the position for at least a minute
- seated repositioning of the patient with the chin towards the chest
- Patient positioned on the healthy side
- a downward rotation of the head by about 45° is performed
- The head is brought back in line with the body and then rotated by about 45° upwards
- The position is maintained for no less than 30 seconds
- Patient placed in a sitting position for at least 3 minutes
MODIFIED SEMONT MANOEUVRE
Otoconial debris can induce spontaneous nystagmus in BPPV of the ASC. In this case, the patient is placed in the Dix Hallpike position to achieve the reversing of the spontaneous nystagmus. Before the end of the nystagmus, the patient, while maintaining the hyperextension of the head, is repositioned sitting. Upon reaching the sitting position, the head is aligned vertically with the trunk.
While the patient is sitting on the examination table, the head is rotated by 45° towards the pathological side and brought down towards the affected side, holding the position for at least 2 minutes. After that, the patient is moved to the other side, so as to make an opposite movement of about 180° without the position of the head ever undergoing changes. This movement must be done slowly. The patient is held in this position for approximately another 2 minutes, after which is brought back to a sitting position rotating the head vertically.
While the patient is on the examination table, the head is moved rapidly off the table in a tilted and dangling position. It is held in this position for about 30-40 seconds, after which the head is raised so that the chin almost reaches the chest. The position is held for a further 30-40 seconds. The patient is then brought back to a sitting position with the legs stretched along the table, while keeping the head always inclined forward, however with a lesser inclination than in the previous position. When the nystagmus detected during the entire execution of this manoeuvre disappears, the head is raised and aligned with the trunk. If necessary, the manoeuvre can be repeated.