KEY FACTS Terminology Subcortical injury (SCI): Deep diffuse axonal injury lesions of brainstem, basal ganglia, thalamus, and regions around 3rd ventricle Intraventricular hemorrhage (IVH): Hemorrhage within ventricular system Choroid hemorrhage (CH): Hemorrhage localized to choroidal plexus Imaging SCI: FLAIR most sensitive → hyperintense foci IVH: Hyperdense intraventricular blood; fluid-heme level common CH: Localized hyperdense choroidal hemorrhage Top Differential Diagnoses SCI: Cavernous malformation, lacunar infarcts, small-vessel ischemia…

KEY FACTS Terminology Traumatic axonal stretch injury Imaging General features Can be hemorrhagic or nonhemorrhagic – Microbleeds important imaging marker for diffuse axonal injury (DAI) – Intraventricular hemorrhage correlates with DAI Location – Subcortical/deep white matter (WM), corpus callosum – Deeper brain involvement = ↑ severity, poor prognosis NECT often normal (50-80%) MR FLAIR: Hyperintense foci T2* GRE: Hypointense “blooming” foci (hemorrhage) SWI: Depicts significantly more…

KEY FACTS Terminology Brain surface injuries involving gray matter and contiguous subcortical white matter Imaging Best diagnostic clue: Patchy hemorrhages within edematous background Characteristic locations: Adjacent to irregular bony protuberance or dural fold Anterior inferior frontal lobes and anterior inferior temporal lobes most common FLAIR: Best for hyperintense cortical edema and subarachnoid hemorrhage GRE: Hypointense hemorrhagic foci “bloom” Best imaging tool CT to detect acute hemorrhagic…

KEY FACTS Terminology Blood within subarachnoid spaces Contained between pia and arachnoid membranes Imaging High density on CT, hyperintensity on FLAIR Top Differential Diagnoses Nontraumatic SAH Meningitis: Cellular and proteinaceous debris Carcinomatosis meningitis Pseudosubarachnoid hemorrhage Gadolinium administration High inspired oxygen Pathology Associated with contusions, subdural or epidural hematoma, diffuse axonal injury Clinical Issues Headache, emesis, decreased consciousness Trauma is most common cause of subarachnoid hemorrhage (SAH)…

KEY FACTS Terminology Intentionally inflicted injury; abusive head trauma, inflicted head injury, nonaccidental head injury Imaging Plays key role in early diagnosis Disparate brain injuries relative to proffered history Skeletal survey, NECT as initial primary imaging tools Detection/characterization of intracranial hemorrhage Detection/characterization of fractures MR Delayed (24-72 hours) for detection of parenchymal injuries, demonstration of unexplained, different-aged subdural hemorrhages (SDHs) – Use T1WI, T2WI, T2*/SWI (best…

KEY FACTS Terminology “Typical” epidural hematoma (EDH) Arterial laceration 90-95% supratentorial (temporoparietal most common) Biconvex, unilateral Atypical EDH Unusual etiology Unusual location Unusual shape or density Imaging Venous EDH (10% of EDHs) Fracture (linear, diastatic) crosses dural venous sinus Skull base, vertex Easily overlooked Coronal, sagittal reformats key to diagnosis Anterior temporal EDH (10% of EDHs) Middle cranial fossa – In front of, not lateral to,…

KEY FACTS Terminology Blood collection between skull and dura Imaging NECT Hyperdense, biconvex, extraaxial collection > 95% unilateral, supratentorial Does not cross sutures unless venous or sutural diastasis/fracture is present Compresses/displaces underlying brain, subarachnoid space Low-density swirl sign: Active/rapid bleeding with unretracted clot 1/3-1/2 have other significant lesions Bone CT Skull fracture in 90-95% Top Differential Diagnoses Subdural hematoma Neoplasm Infection/inflammation Extramedullary hematopoiesis Pathology Arterial (90-95%)…

KEY FACTS Terminology Chronic subdural hematoma (cSDH) Chronic (> 3 weeks to months) subdural blood products Mixed chronic and acute hemorrhage is common Imaging Crescent-shaped extraaxial collection Spreads diffusely over affected hemisphere Surrounded by enhancing membranes Often septated, loculated, with fluid-fluid levels Recurrent, mixed-age hemorrhage is common and raises suspicion of nonaccidental trauma in children Imaging recommendations NECT is good initial screen Use wide window settings…

KEY FACTS Terminology Subacute (~ 3 days to 3 weeks) collection In subdural space (between arachnoid and dura or within inner border cell layer) Partially liquefied clot, resorbing blood products Surrounded by granulation tissue (“membrane”) Imaging Crescent-shaped, iso- to hypodense extraaxial collection Spreads diffusely over hemisphere May cross sutures, not dural attachments May be of same density as underlying cortex Look for inwardly displaced “dots” of…

KEY FACTS Terminology Acute blood between inner border cell layer of dura, arachnoid Imaging NECT as initial screening study Use both bone, soft tissue algorithms Use both standard brain, wide windows (150 HU) Coronal, sagittal reformatted scans best for detecting small subdural hematomas (SDHs) Crescentic hyperdense extraaxial collection Spreads diffusely over cerebral convexity Often extends along falx, tentorium Inward displacement of cortical veins, sulci May cross…

Approach to Head Trauma General Considerations Epidemiology : Trauma is the most common worldwide cause of death and disability in children and young adults. In these patients, neurotrauma is responsible for the vast majority of cases. In the USA and Canada, emergency departments (ED) treat more than 8 million patients with head injuries annually, representing 6-7% of all ED visits. The vast majority of patients with…

KEY FACTS Terminology Li-Fraumeni syndrome (LFS) Autosomal-dominant familial cancer syndrome 75% of LFS cases have loss of function mutations in TP53 tumor suppressor gene Lifelong ↑ risk of osteosarcoma, soft tissue sarcoma, leukemia, breast cancer, brain tumors, melanoma, adrenal cortical tumors Imaging Astrocytoma: Cerebrum > cerebellum > spine Choroid plexus carcinoma: Lateral ventricle > > 4th ventricle Top Differential Diagnoses Hereditary syndromes causing familial cancers, including…

KEY FACTS Terminology Lhermitte-Duclos disease (LDD) Benign cerebellar lesion; unclear if neoplastic, malformative, or hamartomatous Multiple hamartoma syndrome (MHAM) → autosomal dominant, mutation in PTEN gene, associated with increased incidence of malignancy MHAM = Cowden syndrome (CS); Cowden plus Lhermitte-Duclos = MHAM with LDD – CS is most common phenotype of PTEN hamartoma tumor syndrome LDD now considered manifestation of MHAM and neurocutaneous syndrome Imaging Relatively…

KEY FACTS Terminology Hereditary hemorrhagic telangiectasia (HHT) Rendu-Osler-Weber, Osler-Weber-Rendu syndrome Autosomal dominant disorder with widely distributed, multisystem angiodysplastic lesions Mucocutaneous telangiectasias with arteriovenous malformations (AVMs) in visceral organs (primarily lungs, brain, liver) Imaging Best diagnostic clue Multiple pulmonary or cerebral malformations (pAVM/cAVM) in patient with recurrent epistaxis MR “Blooming” of capillary telangiectasias (SWI > GRE) – “Fluffy” enhancement on T1 C+ cAVM: Nest (“tangle”) of flow…

KEY FACTS Terminology Synonyms: Sturge-Weber-Dimitri, encephalotrigeminal angiomatosis Imaging Imaging features are pial angioma with sequelae of chronic venous ischemia Pial angiomatosis unilateral (80%), bilateral (20%) Cortical Ca++, atrophy, and enlarged ipsilateral choroid plexus “Tram-track” calcification in cortex (not angioma) Early: Transient hyperperfusion → “accelerated” myelin maturation Late: Increased signal in region of gliosis and decreased cortical signal in regions of calcification Early: Serpentine leptomeningeal enhancement, pial…

KEY FACTS Terminology Tuberous sclerosis complex (TSC) Multisystem genetic disorder with epilepsy, multiorgan tumors, and hamartomas Spectrum of CNS hamartomas; all contain dysplastic neurons and giant (balloon) cells Caused by mutation in TSC1 or TSC2 gene Now considered an infantile (developmental) tauopathy – Tau abnormally expressed in many dysmorphic neurons and glial cells of TSC – Similar to focal cortical dysplasia (FCD) 2 Imaging FLAIR and…

KEY FACTS Terminology Familial cancer syndrome Multiple cranial nerve (CN) schwannomas, meningiomas, and spinal tumors Imaging Best diagnostic clue: Bilateral vestibular schwannomas Multiple extraaxial tumors Schwannomas of CNs and spinal nerve roots Meningiomas on dural surfaces (up to 50%) Intraaxial tumors Ependymomas in spinal cord and brainstem (6%) Recommendation: Use high-resolution T1 C+ FS MR through basal cisterns to evaluate cranial nerves Top Differential Diagnoses Schwannomatosis…

KEY FACTS Terminology Neurofibromatosis type 1 (NF1), von Recklinghausen disease, peripheral neurofibromatosis Imaging Benign hyperintense white matter (WM) lesions on T2WI in 70-90% of preteen children Lesions are poorly defined, no mass effect/enhancement May also involve cerebellar WM, globus pallidus, thalamus, brainstem Wax, then wane; disappear by 20 years of age Neoplasms Plexiform neurofibromas – Sphenoid wing and occipital bone dysplasia found in association with plexiform…

KEY FACTS Terminology Autosomal-dominant familial syndrome with hemangioblastomas (HGBLs), clear cell renal carcinoma, cystadenomas, pheochromocytomas Imaging 2 or more CNS HGBLs or 1 HGBL plus visceral lesion or retinal hemorrhage HGBLs vary from tiny mass to very large with even larger associated cysts Top Differential Diagnoses Vascular metastasis Solitary HGBL Pilocytic astrocytoma Hemispheric medulloblastoma in teenager or young adult Multiple arteriovenous malformations in vascular neurocutaneous syndrome…

KEY FACTS Imaging Transmantle gray matter (GM) lining clefts Look for dimple in wall of ventricle if cleft is narrow/closed Up to 1/2 of schizencephalies are bilateral When bilateral, 60% are open-lipped on both sides GM lining clefts may appear hyperdense Ca++ when associated with CMV or COL4A1 mutations Prior to myelination, T2WI more clearly defines lesion Top Differential Diagnoses Encephaloclastic porencephaly Lined by gliotic white…