Neurological examination quiz Part 4

A child should be able to move towards light and fixate by 2 weeks post partum. (link)

Normal visual development in children is characterised by the presence of doll’s-eye movements at birth and development of conjugate eye movements soon after birth. By 2 weeks of age the eyes should move toward light and fixate but complete following movements in all directions does not occur until approximately 4 months of age. Acoustically elicited eye movements appear by 5 months of age and depth perception, stable binocular alignment and the capacity for nystagmus appear by 24 months of age. (link)

Optic disk lesions are the most likely to cause an ipsilateral central scotoma as demonstrated. A partial optic nerve lesion usually causes a ipsilateral unilateral nasal or temporal field defect, although a lesion in the centre of the L optic nerve (very uncommon) could cause this type of defect. Right optic radiation or occipital lobe lesions cause a left sided homonymous hemianopia. (link)

Optic disk lesions are more likely to cause an ipsilateral central scotoma, than complete unilateral blindness as demonstrated. A complete optic nerve lesions is the most likely cause of this type of defect. Left optic radiation or occipital lobe lesions cause a right sided homonymous hemianopia. (link)

A right sided temporal aspect optic nerve lesion causes a right nasal hemianopia. A right sided optic tract lesion would cause a left sided homonymous hemianopia. An occipital lobe lesion would cause a homonymous hemianopia and a left optic radiation lesion would cause a right sided homonymous hemianopia, not bitemporal, if complete. (link)

Optic chiasmal lesions cause bitemporal hemianopia as demonstrated. Bilateral temporal partial optic nerve lesions would cause binasal hemianopia. Bilateral occipital lobe lesions cause complete blindness. A left optic radiation lesion would cause a right sided homonymous hemianopia, not bitemporal, if complete. (link)

Optic tract lesions tend to give complete homonymous hemianopia on the opposite side of the lesion. A right optic radiation lesion would cause a left sided (not right sided) hemianopia if complete. Optic chiasmal lesions cause bitemporal hemianopia and bilateral occipital lobe lesions cause complete blindness.(link)

The defect is most likely due to a left occipital cortex lesion. Macular sparing may be present with lesions at this location as the blood supply of the occipital pole of the visual cortex can be from the middle cerebral artery instead of the posterior cerebral artery.(link)

Athough lower quadrantanopia is traditionally stated as being due to a parietal lobe lesion affecting the optic radiation, about 80% of cases are due to occipital lobe lesions.(link)

Athough upper quadrantanopia is traditionally stated as being due to a temporal lobe lesion affecting the optic radiation, about 80% of cases are due to occipital lobe lesions. (link)

Pendular nystagmus is usually congenital, downbeat nystagmus is acquired and associated with lesions around the foramen magnum. As eye movements have equal speed in pendular nystagmus (unlike the fast – slow speed of jerky nystagmus) it can be difficult to differentiate from ocular clonus. (link)

Either right sided vestibular or cerebellar lesions can cause nystagmus to the right, however vestibular lesions are more common than cerebellar lesions in ED practice particularly if unilateral. (link)

Periodic alternating nystagmus is associated with posterior fossa lesions. Pendular nystagmus is usually congenital or associated with severe visual impairment. (link)

Nystagmus due to a central cause does not fatigue. (link)

There is a  2- 20 second latency from stimulus (e.g. Nylen-Barany (Hallpike) manoeuvre) to the onset of nystagmus in peripheral lesions, in contrast to central lesions that have an immediate onset of nystagmus. (link)