Shu Yi Teh

Introduction

Abusive Head Trauma (AHT) in young children refers to repeated acceleration-deceleration abusive injury with or without blunt head impact (1). Abnormal eye findings are frequently observed in children with AHT, for example retinal haemorrhages, vitreous haemorrhages, or optic nerve sheath (the latter visible only on autopsy) and less commonly, retinoschisis or peri-macular retinal folding (2).

Ophthalmologic Findings

Retinal haemorrhages

Retinal haemorrhages have been recognised as an important indication of abusive head injury (3), and that the positive findings or retinal haemorrhage significantly increases suspicion for trauma and inflicted injury but does not necessarily confirm the diagnosis and vice versa.

Description of the number, the distribution pattern, the types and severity of haemorrhages have diagnostic and prognostic implications (4). Studies have shown strong association between severe retinal haemorrhages and AHT, and that the number and severity of retinal haemorrhages correlate with the severity of neurologic injury (2,5). Bilateral retinal haemorrhages are more commonly seen in AHT, but asymmetry and unilaterality are also well recognised (6). Retinal haemorrhages can extend to the ora serrata or can be confined to the peripapillary area or posterior pole. Retinal haemorrhages can be subretinal, intraretinal, or preretinal and may extend into the vitreous (2). Dense or extensive preretinal or vitreous haemorrhage may also obscure underlying retinal haemorrhage.

Retinal haemorrhages in AHT can range from mild to severe. Mild refers to few intraretinal haemorrhages primarily in the posterior pole, usually in a peripapillary and perivascular pattern. Whilst the severe spectrum is diffusely distributed multi-layered retinal in the posterior pole and retinal periphery haemorrhages that are too numerous to count, with also haemorrhages present in the far retinal periphery nearing ora serrata. The midperiphery of the retina and central macula may be spared, but there may be macular findings of retinoschisis, circumlinear fold or haemorrhagic cyst as well.

The severity of trauma is in proportional correlation with the severity of retinal haemorrhages, and specific findings that indicate increased severity include greater number of haemorrhages, presence of intraretinal haemorrhage with preretinal or subretinal haemorrhage, anterior extension of haemorrhages beyond the posterior pole and far into the retinal periphery, presence of circum-macular retinal folds or macular retinoschisis (2).

The pattern of retinal haemorrhages could also provide useful information to estimate the timing of the traumatic event (7). Intraretinal haemorrhages suggests a more acute injury as it starts to resolve within 24 to 48 hours, with most clearing in the first or second week. Preretinal haemorrhage in AHT is always accompanied by intraretinal haemorrhage and represents a more chronic injury as it takes longer to clear which may range from weeks to months). Retinal scars and optic atrophy indicate a distant previous injury which may be months ago or longer, as they take time to develop. (7).

Retinal folds and retinoschisis

Circular retinal folds centred on the macula are not a pathognomonic finding in AHT but can be indicative of severe trauma (1). They can occur after fatal car accident, crush injuries to the head, and falls from great heights (8). They typically result from strong forces that cause shearing or traction on the retina, especially near the macula.

Both peripheral and macular traumatic retinoschisis may develop in AHT and can be only a subtle finding. Haemorrhage within the split retinal layers is also known as haemorrhagic macular cyst. In many instances of retinoschisis, only the internal limiting membrane and/or the nerve fibre layer is separated by the vitreous, due to the strong vitreous attachment in infants. However, deeper schisis and focal macular detachment can occur as well (9). Histological findings may include depigmentation of the retinal pigmented epithelium underlying the folds and attachment of the vitreous at the edges of the lesion (10).

A hypopigmented or haemorrhagic arc or elevated retinal fold may surround the schisis cavity. The retinal fold may surround the entire posterior pole, along with the optic nerve, or may encompass only the macula. It can occur as continuous, discontinuous, or as an arc. Retinal folds are typically consequential of fatal injury that may results in death or neurologic sequelae. However, some patients have demonstrated good visual recovery (10).

Vitreous haemorrhage

Vitreous haemorrhage may be present at the first examination shortly after injury and can obscure fundus detail. It may also occur days later from rupture of the internal limiting membrane over a haemorrhagic cyst (10).

Papilledema

Papilledema, also known as optic disc swelling, is caused by raised intracranial pressure. The prevalence of papilledema in AHT cases is approximately 10 percent and typically takes 12 to 24 hours to develop in patients with elevated intracranial pressure after a head injury. Therefore, initial presentation with papilledema may suggest delay in seeking care post AHT and is an ominous finding associated with high mortality (6).

Optic nerve sheath haemorrhage

Optic nerve sheath haemorrhage is frequently observed in patients with AHT but can appear in individuals with non-abusive head injuries as well. It tends to be most noticeable in the anterior portion of the optic nerve but may not span the entire length of the nerve and does not always occur alongside retinal haemorrhage. It often involves multiple layers around the optic nerve, with a concentration of haemorrhage typically found in the subdural space (11).

Other orbital trauma

Additional signs of orbital trauma caused by acceleration-deceleration forces, often observed during autopsy, include intradural haemorrhage of the optic nerve as well as haemorrhages in the orbital fat, extraocular muscles, or cranial nerve sheaths (12).

References

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2. Bhardwaj, G. et al. (2010) ‘A systematic review of the diagnostic accuracy of ocular signs in pediatric abusive head trauma’, Ophthalmology, 117(5). doi:10.1016/j.ophtha.2009.09.040.
3. Al-Holou, W.N. et al. (2009) ‘Nonaccidental head injury in children’, Journal of Neurosurgery: Pediatrics, 3(6), pp. 474–483. doi:10.3171/2009.1.peds08365.
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8. Lantz, P.E. et al. (2004) ‘Perimacular retinal folds from childhood head trauma’, BMJ, 328(7442), pp. 754–756. doi:10.1136/bmj.328.7442.754.
9. Greenwald, M.J. et al. (1986) ‘Traumatic retinoschisis in battered babies’, Ophthalmology, 93(5), pp. 618–625. doi:10.1016/s0161-6420(86)33688-1.
10. Gaynon, M.W. et al. (1988) ‘Retinal folds in the shaken baby syndrome’, American Journal of Ophthalmology, 106(4), pp. 423–425. doi:10.1016/0002-9394(88)90877-x.
11. Budenz, D.L. et al. (1994) ‘Ocular and optic nerve hemorrhages in abused infants with intracranial injuries’, Ophthalmology, 101(3), pp. 559–565. doi:10.1016/s0161-6420(94)31300-5.
12. Wygnanski-Jaffe, T. et al. (2006) ‘Postmortem orbital findings in shaken baby syndrome’, American Journal of Ophthalmology, 142(2). doi:10.1016/j.ajo.2006.03.038.