Main directions of differential search
The presence of subdural fluid collections does not always unambiguously indicate physical abuse. When formulating a diagnosis, the following conditions must be excluded:
- Coagulopathies (blood clotting disorders).
- Sequelae of previous diseases: subdural effusions can develop against the background of acute severe dehydration or as a complication of meningitis.
- Congenital metabolic disorders: glutaric aciduria type I (glutaric aciduria type I) and Menkes disease (Menkes disease).
Types of injuries and imaging modalities
The nature of injuries in shaken baby syndrome (shaken baby syndrome) is determined by the biomechanics of the impact. Main imaging findings include:
- Intraventricular hemorrhages. They occur due to the rupture of subependymal veins. In the acute stage, they are clearly visible on CT, while in the chronic stage, they are better detected on MRI (T2* or SWI sequences). They are dangerous due to the development of secondary obstructive hydrocephalus (which must be distinguished from passive ventricular enlargement in brain atrophy).
- Retinal hemorrhages (retinal haemorrhages). They are a highly specific marker of non-accidental trauma. In addition to ophthalmoscopy, they can be noticed on orbital MRI scans (in susceptibility-weighted sequences).
- Intraparenchymal hemorrhagic contusions. They usually localize at the gray-white matter junction. On fresh CT scans, they appear hyperdense, with density decreasing over time. T1-weighted MRI better visualizes them in the subacute stage due to hemoglobin degradation products.
Specific neuroradiological signs
MRI has high sensitivity in detecting venous thrombosis and blood breakdown products. A detailed analysis of SWI images can reveal thrombi within bridging veins (bridging veins). In foreign literature, these signs are described as the tadpole sign (tadpole sign) and the lollipop sign (lollipop sign).
Pathognomonic findings also include:
- Presence of fluid-fluid levels within subdural hematomas.
- Thrombosis of deep medullary veins.
- Reversal sign (reversal sign) on CT: due to diffuse parenchymal hypoattenuation (resulting from edema), the cerebellum visually appears denser than the cerebral hemispheres.
Prognostically important information is provided by MR spectroscopy. A decrease in the N-acetylaspartate peak (a marker of neuronal viability) combined with a high lactate peak (a sign of anaerobic glycolysis and ischemia) indicates severe brain damage and an unfavorable clinical outcome.
Musculoskeletal trauma and spinal lesions
Spinal injuries often go unnoticed during the evaluation of patients with Abusive Head Trauma, although they are closely associated with this syndrome.
All children with suspected non-accidental trauma are recommended to undergo MRI of the entire spinal column. Attention should be paid to:
- Spinal cord signal changes: may indicate infarction or contusion.
- Epidural and subdural hemorrhages. Evaluating the epidural fat tissue helps differentiate them (if preserved, the hemorrhage is likely subdural). Nodal or diffuse thickening of the dura mater with compression of the dural sac is also observed.
- Neck injuries. Ligamentous injuries and muscle edema are well detected on fat-suppressed fluid-sensitive sequences (fat-saturated fluid-sensitive sequences).
Imaging strategy
In an emergency situation, the method of choice is non-contrast head computed tomography, which allows rapid exclusion of life-threatening hemorrhages. For subsequent follow-up and detailed assessment of parenchymal injuries, MRI is mandatory. The protocol should include T1, T2, diffusion-weighted imaging (DWI) to assess cytotoxic edema, as well as T2* or SWI.
Data interpretation should be performed by a specialist experienced in pediatric trauma. Determining the exact age of injuries (dating) presents significant difficulty and requires an extremely cautious multidisciplinary approach.
Briefly: answers to topical questions
What types of intracranial hemorrhage are typical for shaken baby syndrome?
Shaken baby syndrome is most commonly characterized by subdural and intraventricular hemorrhages.
- Subdural hematoma (Subdural haematoma) is the most frequent type of intracranial hemorrhage in non-accidental trauma, often bilateral, closely adhering to the falx cerebri and layering along the tentorium cerebelli.
- Intraventricular hemorrhage (Intraventricular haemorrhage) is associated with subependymal vein injury and may be complicated by secondary obstructive hydrocephalus.
Subarachnoid hemorrhages and parenchymal injuries, including intraparenchymal hemorrhagic contusions (Intraparenchymal haemorrhagic contusions), may also be detected.
What bone lesions and skeletal fractures are most specific for child abuse syndrome?
The most specific findings for child abuse syndrome are classic metaphyseal lesions and fractures in specific locations.
Highly specific injuries include:
- Classic metaphyseal lesion (Classic metaphyseal lesion - CML) — a series of microfractures across the entire width of the metaphysis.
- Rib fractures — especially of the posterior segments.
- Scapular fractures.
- Spinous process fractures.
- Sternal fractures.
Multiple bilateral fractures, fractures of different ages, epiphyseal separation (Epiphyseal separation), phalangeal fractures, and complex skull fractures have moderate specificity.
How to differentiate acute, subacute, and chronic subdural hematomas on CT?
The differential diagnosis of subdural hematoma (SDH) stages on CT is based on changes in the X-ray density of collections and the presence of membranes.
| SDH Stage | CT appearance |
|---|---|
| Acute | Predominantly hyperdense collections (may be isodense in anemia or CSF dilution). |
| Subacute | Density varies from slightly hyperdense to isodense relative to the brain parenchyma. |
| Chronic | Hypodense collections. |
Subacute and chronic stages differ from acute stages by the presence of reactive granulation tissue membranes, which appear on CT as septa within an iso- or hypodense hematoma.
Class and exam questions
Why is SWI MRI ordered when child abuse is suspected?
Susceptibility-weighted imaging (SWI) has maximum sensitivity to blood breakdown products. It allows the detection of minute parenchymal hemorrhages, microthrombi in bridging veins, and retinal hemorrhages.
What MRI findings indicate acute cerebral ischemia?
Acute hypoxia and ischemia are indicated by restricted water molecule diffusion on diffusion-weighted images (DWI) and ADC maps, which is a sign of developing cellular cytotoxic edema.
What long-term consequences of diffuse brain injury are visible on imaging?
The outcome of severe hypoxic-ischemic injuries on CT and MRI is visualized as pronounced secondary brain atrophy or the formation of multicystic encephalomalacia.
What else to study on this topic
- Mechanisms of secondary obstructive hydrocephalus formation in intraventricular hemorrhage
- Evaluation of MRI healing patterns of fractures in young children
- Methodology of using ASL perfusion to assess cerebral blood flow asymmetry
- Differential diagnosis of epidural and subdural spinal hematomas
- Legal and forensic significance of documenting cervical spine injuries
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