Carol is a 62 year old female who has had episodes of dizzy spells over the last few weeks. Carol explains that episodes usually occur upon waking as she rolls over and sits up in bed. She immediately feels ‘the world is spinning’ around her for approximately a minute before symptoms spontaneous resolve. The last two episodes were associated with nausea and vomiting. Carol denies any hearing loss, tinnitus or headaches. She is normally fit and well, though you notice from her medical records she was involved in a road traffic accident last year.
Systems examination including neurological examination is intact. Dix-Hallpike manoeuvre provokes a clockwise torsional nystagmus and vertigo lasting approximately 45seconds.
What is the most likely diagnosis?