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Sir,

The shaken baby syndrome is a serious and clearly definable form of child abuse caused by the violent shaking of young children with or without impact injuries.1 These children typically have intracranial and intraocular haemorrhages.2 Survivors may demonstrate a variety of neurological, intellectual, and ocular motility sequelae.2 We present a case of vertical nystagmus following a shaking injury in an infant.

Case report

An 8-week-old male infant was referred to The Hospital for Sick Children for management of uncontrolled seizures following diffuse brain injury resulting from a shaking injury. The diagnosis of shaken baby syndrome was made at the referring hospital on the basis of the clinical findings: subdural intracranial haemorrhage and retinal haemorrhages occurring in a characteristic pattern2 in the absence of any other identifiable medical cause. A second ophthalmologic consult was requested as the child had been noticed to have abnormal eye movements.

On examination, there was a blink reflex to bright light, but the child was unable to fix and follow, and there was no optokinetic response. The pupillary light reactions were sluggish bilaterally; there was no relative afferent pupillary defect. There was a constant, large-amplitude vertical pendular nystagmus of moderate frequency. The anterior segment examination was normal. Dilated fundus examination revealed vitreous and posterior pole haemorrhages in the right eye, involving the macula. In the left eye, there was a dense vitreous haemorrhage with no view of the retina. B-scan ultrasound demonstrated no retinal detachment in either eye. Magnetic resonance imaging (MRI) of the brain revealed bilateral subdural haemorrhages and diffuse infarction of cerebral cortex, with extensive loss of cortex consistent with a profound ischaemic event, but relative preservation of the brainstem.

At follow-up examinations 4 and 7 months later, the vertical nystagmus had resolved, though the eyes showed conjugate, random movements. Visual function was unchanged. Fundus examination showed resolution of all intraocular haemorrhages, bilateral optic atrophy, macular scarring, and vitreous veil formation in the left eye. There was a preretinal gliotic membrane bilaterally (Figure 1). Neuroimaging demonstrated severe atrophic changes throughout the cerebral cortex.

Figure 1
figure 1

Right fundus photograph 4 months following shaking injury. The intraocular haemorrhages have cleared, revealing optic disc pallor, atrophic, and pigmentary change at the macula and preretinal gliosis with retinal wrinkling.

Full size image

Comment

To our knowledge, there are no reports in the literature of nystagmus following shaking injuries in children. The shaken baby syndrome is a serious and clearly definable form of child abuse caused by the violent shaking of young children with or without impact injuries.1 Our case was typical of shaking injuries in most respects. These children typically have subdural or subarachnoid intracranial haemorrhage visible on neuroimaging.2 Intraocular haemorrhages are common following injuries occurring in at least 80% of cases, usually bilaterally.2 The injuries are fatal in nearly one-third of the children.2 Approximately 20% of survivors have reduced vision that is usually cortical in origin and highly correlated with severe neurologic outcome. Poor vision may sometimes, however, result from anterior pathway injuries such as optic atrophy or vitreous haemorrhage.2

Sensory nystagmus results from bilateral anterior visual pathway disease, in this case intraocular haemorrhages, whereas cortical visual loss typically does not cause sensory nystagmus. Sensory nystagmus is usually horizontal or rotary, but may sometimes be vertical. Vertical nystagmus in adults is most commonly due to intracranial pathology. Children however may demonstrate vertical nystagmus in the presence of normal neuroimaging, this nystagmus is invariably associated with poor visual acuity.3,4,5 In most children where the sensory nystagmus persists, the nystagmus eventually becomes horizontal in direction.4

The child described above developed vertical, pendular sensory-type nystagmus following a shaking injury with documented intracranial and intraocular haemorrhages. Resolution of the nystagmus coincided with clearing of the intraocular haemorrhages. The ocular movements then reverted to conjugate, random movements characteristic of cortical visual impairment. We postulate that this child developed reversible sensory nystagmus as a result of the occlusive effect of the intraocular haemorrhages. Future reporting of similar cases may clarify whether sensory nystagmus is more likely to be vertical in the presence of diffuse brain injury from shaking or other causes.