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Differential Diagnosis of Nervous System Disorders

Classification of Vascular CNS Anomalies!!navigator!!

  1. VASCULAR MALFORMATION
    1. arterial = arteriovenous malformation (AVM)
      1. Classic brain AVM
      2. Cerebral proliferative angiopathy
      3. Cerebrofacial arteriovenous metameric syndrome
      4. Vein of Galen malformation
    2. capillary = capillary telangiectasia
      1. Capillary telangiectasia
      2. Facial port-wine stain
    3. venous = venous malformation
      1. Developmental venous anomaly
      2. Sinus pericranii
    4. lymphatic
      1. Cystic hygroma
    5. combinations
      1. Sturge-Weber disease
      2. Rendu-Osler-Weber disease
  2. VASCULAR TUMOR
    1. Hemangioma
      1. capillary hemangioma: seen in children, involution by 7 years of age in 95%
      2. cavernous hemangioma: seen in adults, no involution
    2. Hemangiopericytoma
    3. Hemangioendothelioma
    4. Angiosarcoma

Blunt Cerebrovascular Injury!!navigator!!

= carotid (CA) + vertebral artery (VA) injuries during generalized multitrauma / direct craniocervical trauma

Prevalence: 1.1–1.6% of all blunt trauma

Mechanism: partial / complete failure of arterial mural integrity ← longitudinal stretching of artery, direct blow to artery, piercing by bone fragment

Prognosis: 25–38% mortality if injury untreated

Cx:

  1. Infarction ← intimal disruption / flap / hematoma
    → thromboembolism of platelet aggregates
    →critical luminal stenosis + occlusion
  2. Brain ischemia ← steal phenomenon by AV fistula
  3. Fatal exsanguination

Type of Arterial Injury

  1. Minimal intimal injury
    • nonstenotic luminal irregularity
      DDx: arterial spasm
  2. Raised intimal flap
    • linear intraluminal filling defect emanating from arterial wall
  3. Dissection with intramural hematoma
    • eccentric / circumferential mural thickening:
      • narrowed arterial lumen
      • increased arterial diameter
  4. Arterial occlusion
    • lack of intraluminal enhancement
  5. Pseudoaneurysm
    • eccentric outpouching from native arterial lumen:
      • minimal contour abnormality
      • large irregular saccular outpouching
    • focal ballooning of arterial lumen
  6. Transection with active hemorrhage
    • irregular collection of extravascular contrast material surrounding parent vessel
  7. Arteriovenous fistula
    • early venous enhancement during the arterial phase
    • enlargement of draining vein

DDx:

  1. Atherosclerosis (presence of calcification, characteristic location, increasing age)
    Location: vessel origin, carotid bulb, cavernous carotid segment
  2. Coiled / looped cervical ICA segment (5–15%)
  3. Congenitally absent / small ICA (small / absent carotid canal)

Shunt Lesions of Cerebral Vasculature!!navigator!!

  1. AV malformation
  2. AV fistula: pia, dura, carotid-cavernous sinus
  3. Vein of Galen malformation

Congenital Venous Lesions!!navigator!!

  1. Developmental venous anomaly
  2. Cerebral cavernous malformation
  3. Sinus pericranii

Occlusive Vascular Disease!!navigator!!

  1. Embolic state:
    • single vascular territory
  2. Hypoperfusive state:
    • multiple vascular territories

Cause:

  1. Vasospasm from subarachnoid hemorrhage
  2. Embolic infarction (50%)
    1. thrombus (atrial fibrillation, valvular disease, atheromatous plaques of extracerebral arteries, fibromuscular dysplasia, intracranial aneurysm, surgery, paradoxic emboli, sickle cell disease, atherosclerosis, thrombotic thrombocytopenic purpura)
      • fluctuating blood pressures; hypercoagulability
      • cerebral petechial hemorrhage within cortical / basal gray matter during 2nd week (from fragments of embolus) in up to 40%; initial ischemia is followed by reperfusion (= HALLMARK of embolic infarction)
      • “supernormal artery” on NECT = high-density material lodged in cerebral vessel near major bifurcations
      • atheromatous narrowing of vessels
    2. fat
    3. nitrogen
  3. Watershed / border zone infarct (10%)
  4. Hypertension
    1. Hypertensive encephalopathy
      • diffuse white matter hypodensity (edema ← arterial spasm)
    2. Hypertensive hemorrhage
      Location: basal ganglia (putamen, external capsule), thalamus, pons, cerebellum
    3. Lacunar infarction
    4. Subcortical arteriosclerotic encephalopathy
  5. Amyloidosis
    involvement of small- + medium-sized arteries of meninges + cortex
    • normotensive patient >65 years of age
    • multiple simultaneous / recurrent cortical hemorrhages
  6. Vasculitis
    1. Bacterial meningitis, TB, syphilis, fungus, virus, rickettsia
    2. Collagen-vascular disease: Wegener granulomatosis, polyarteritis nodosa, SLE, scleroderma, dermatomyositis
    3. Granulomatous angiitis: giant cell arteritis, sarcoidosis, Takayasu disease, temporal arteritis
    4. Inflammatory arteritis: rheumatoid arteritis, hypersensitivity arteritis, Behçet disease, lymphomatoid granulomatosis
    5. Drug-induced: IV amphetamine, ergot preparations, oral contraceptives
    6. Radiation arteritis = mineralizing microangiopathy
    7. Moyamoya disease
  7. Anoxic encephalopathy
    cardiorespiratory arrest, near-drowning, drug overdose, CO poisoning
  8. Venous thrombosis

Multiple Infarctions

◊Typical in extracranial occlusive disease, cardiac output problems, small vessel disease; in 6% from a shower of emboli

Location: usually bilateral + supratentorial (¾); supra- and infratentorial (¼)

Reversal Sign!!navigator!!

= inversion of the normal attenuation relationship between gray and white matter (gray matter of lower attenuation than adjacent white matter of thalami, brainstem, cerebellum) on NECT of brain

Pathogenesis: not fully understood

Cause: global cerebral injury with anoxic insult ← head trauma, nonaccidental trauma, hypoxia, drowning, status epilepticus, hypothermia, bacterial meningitis, strangulation

Prognosis: poor ← irreversible brain damage; survivors with profound neurologic deficits + severe developmental delay

Diffusion Weighted Imaging (DWI)!!navigator!!

Hyperintense Lesion on DWI

  1. Cerebral infarction
  2. Epidermoid inclusion cyst
  3. Abscess with pus
  4. Encephalitis of cortex
  5. Creutzfeldt-Jakob disease
  6. Trauma: axonal shearing injury
  7. Neoplasm: medulloblastoma

Innumerable Punctate Hyperintense Lesions on DWI

= Starfield pattern

  1. Diffuse axonal injury (trauma)
  2. Emboli: cardiogenic, septic, fat
  3. Vasculitis
  4. Minute hemorrhagic metastases

Hypointense Lesion on DWI

  1. CSF
  2. Tumor cyst: pilocytic, hemangioblastoma
  3. Tumor nodules: hemangioblastoma

False Penumbra on Perfusion CT!!navigator!!

True penumbra: successfully treatable with thrombolysis

  • mean transit time (MTT) ↑
  • cerebral blood flow (CBF) ↓
  • cerebral blood volume (CBV) ↔

False penumbra: area of abnormal perfusion as in ischemic penumbra NOT treatable with thrombolysis

  1. Atherosclerosis at carotid bifurcation
    = upstream flow limitation WITHOUT significant intracranial collateral blood supply
    • carotid bulb disease by CT angiography
  2. Evolving ischemic condition / chronic infarct
    = delayed reperfusion + vascular collateralization of incomplete acute / chronic infarct
    • hypoattenuation in the same region
    • restricted diffusion on DWI + ADC map
  3. Vascular dysregulation
    = hyperemia on symptomatic side with apparent perfusion abnormality on contralateral normal side
    • clinical history!

    Cause:
    1. Hypertensive encephalopathy (PRES)
      • perfusion abnormality ← vasospasm
      • hyperintensity on STIR sequence
      • no restricted diffusion
    2. Seizure, subarachnoid hemorrhage, hemiplegic migraine
      • seizure activity
      • no restricted diffusion
  4. Head tilt / angulation
  5. Variations in cerebrovascular anatomy
    = physiologic perfusion delay in circle of Willis variants, unequal blood supply between anterior + posterior circulation, congenitally absent ICA, etc.

CNS Vasculitis!!navigator!!

  1. LARGE-VESSEL VASCULITIS
    1. Takayasu arteritis
    2. Giant cell arteritis = Temporal arteritis
  2. MEDIUM-SIZED–VESSEL VASCULITIS
    1. Polyarteritis nodosa
      • aneurysm / stenosis / occlusion of intracranial carotid arteries
    2. Kawasaki disease
      • nonspecific subdural effusion, cerebral infarction
      • reversible hyperintense lesion in splenium
  3. SMALL-VESSEL VASCULITIS
    1. IgA vasculitis = Henoch-Schönlein purpura
      • hypertensive encephalopathy
      • focal ischemic / hemorrhagic lesions
    2. Microscopic polyangiitis
      • cerebral hemorrhage + infarction, pachymeningitis
      • variable degree of small-vessel disease
    3. Granulomatosis with polyangiitis
      = Wegener granulomatosis
      • leptomeningeal enhancement
    4. Eosinophilic granulomatosis with polyangiitis
      = Churg-Strauss syndrome
      • macro- / microinfarctions + macro- / microhemorrhages
      • optic neuropathy
  4. VARIABLE-SIZED VESSEL VASCULITIS
    1. Behçet disease
    2. Cogan syndrome
      • nonspecific ischemic changes
      • obliteration / narrowing of vestibular labyrinth
  5. SINGLE-ORGAN VASCULITIS
    1. Primary angiitis of CNS (PACNS)
      • discrete / diffuse supra- and infratentorial lesions
      • ± areas of infarction and hemorrhage
  6. VASCULITIS OF SYSTEMIC DISEASE
    1. Systemic lupus erythematosus (SLE)
      • subcortical + periventricular white matter hyperintensity (60%)
      • cerebral atrophy (30%), intracranial hemorrhage (3%)
    2. Sjögren syndrome
      • extensive white + gray matter lesions + microbleeds
    3. Rheumatoid arthritis
      • pachymeningitis with leptomeningeal enhancement
      • cerebral vasculitis (rare)
    4. APLA (antiphospholipid antibody) syndrome
      • arterial / venous thrombosis, thrombocytopenia
    5. Scleroderma
      • nonspecific infarction, macro- and microhemorrhages
  7. VASCULITIS WITH PROBABLE ETIOLOGY
    1. Infection-induced vasculitis
    2. Acute septic meningitis
      • cerebral infarcts (5–15% in adults, 30% in neonates)
    3. Mycobacterium tuberculosis
      • vasculitis of smaller cerebral arteries → small infarcts in basal ganglia
    4. Neurosyphilis
      • predominantly MCA stroke in young adult
    5. Viral (in childhood):
      • HIV-related vasculitis
        • aneurysm, vessel occlusion, embolic disease, venous thrombosis
      • Varicella-zoster vasculopathy
        • uni- / bilateral basal ganglia infarcts
    6. Fungal: mucormycosis aspergillosis
    7. Parasitic: cysticercosis
    8. Malignancy-induced vasculitis
    9. Drug-induced vasculitis
      • cocaine
        • vasculitis, vasospasm, infarction, moyamoya-like
      • heroin
        • spongiform leukoencephalopathy
    10. Radiation-induced vasculitis
      • wall thickening + prominent wall enhancement in affected large arteries
    11. Reversible cerebral vasoconstriction syndrome: Call-Fleming syndrome, postpartum angiopathy, migrainous vasospasm, benign angiopathy of CNS, vasoactive substances (cannabis, selective serotonin recapture inhibitors, nasal decongestants)

Imaging signs of cerebral vasculitis:

  1. direct
    • vessel wall thickening
    • vessel wall enhancement with contrast material
  2. indirect
    • cerebral perfusion deficit
    • ischemic brain lesion
    • intracerebral / subarachnoid hemorrhage
    • vascular stenosis

Outline