Читать книгу Neurology - Charles H. Clarke - Страница 113

A rarity, compared with others:

 Double vision on looking down, twisted images, a.k.a. torsional diplopia

 Head tilt: away from side of superior oblique weakness

 No obvious squint.

When diplopia does not fit one of the patterns above, Formal Rules help.

1 False image: usually the less distinct and more peripheral

2 Diplopia: occurs in positions dependent upon contraction of a weak muscle

3 False image: is projected in direction of pull of the weak muscle

4 Image separation: increases in direction of pull of the weak muscle.

Dificulties: these include myasthenia, where diplopia varies; also blurring/false‐framing is easily accomplished, sometimes deliberately, by converging too closely. Diplopia is normal at extremes of gaze.