Obstructive Sleep Apnea-MRI

A young adult with clinical sleep apnoea (lasting more than 10 seconds and atleast 5 per hour), with polysomnography suggesting moderate OSA (Obstructive sleep apnoea) on Dynamic MR shows significant reduction of oropharyngeal air column under induced sleep and mullers manoevuer, with absence of air column in atleast one image in the cinemode.

Teaching Points By Dr MGK Murthy, Mr Hari Om, Dr Sumer Sethi.

Sleep apnoea is common snoring medicle problem ocuring predominantly in males between 30 to 60 years, leading to day time sleeping and loss of man hours.

Three types are described :

          a) Central where, neural drive is reduced.
          b) Obstructive where, oropharyngeal (Velopharynx), air way narrowing / occlusion – Most common.
          c)  Mixed – Central variety superadded with obstructive component..

Radiology (Primarly MR in mid sagittal and mid axial slices) plays signifiant role in anatomic delineation of the abnormalities including presence of retrognathia, macroglosia, bulky soft palate, high arched palate, posteriorly located palate, reduced mandibulohyoid distance etc.

It also plays a role in demonstration of functional abnormality in induced sleep - Reduced measurements of oropharyngeal air column in wakeful and sleeping state.

Mullers Manoevure (Reversal of Valsalva) can practically replace need for Induction of the sleep in the gantry, demonstrating similar accuracy.

Upto 50 % of reduction of the airway in wakeful to sleeping is considered normal.

More than 70 % is significant.

More than 90 % with atleast one image in the cine-acquisition showing absence of the aircolumn is pathognomic.

Lateral pharyngeal wall collapse leads to 'T' shaping of the sleeping state air column in these patients.