DIFFERENTIAL DIAGNOSISFOR BILATERAL ABNORMALITIES

OF THE BASAL GANGLIAAND THALAMUS

Dr Roshan Valentine

PG Resident

St Johns Medical College

INTRODUCTION• Abnormalities of basal ganglia seen in various conditions.• MR – IOC• CT - emergency situations – altered sensorium / acute seizures.• In this article , we review the MRI anatomy of basal ganglia and

pathology conditions of these brain structures

ANATOMY• Deep gray matter include paired

BG and thalamus• Here we restrict to abnormalities

of lentiform nucleus and caudate nucleus

• Lentiform N : GP(D) + Putamen(I)• Caudate N (I)• Basal ganglia involved in

production of movement and in memory , cognition and emotion.

ANATOMY• LFN is rich in mitochondria , vascular supply , neurotransmitters –

high metabolic activity and oxygen uptake - vulnerable to metabolic abnormalities

• Thalamus is paired structure on either side of third ventricles. • Responsible for relaying sensory and motor signals to and from the

cerebral cortex• Disorders of thalamus affects consciousness and abnormalities of

sensation

ANATOMYBLOOD SUPPLY• BG : Medial and lateral

lenticulostriate arteries• Thalamus : PCA and PCOM• Venous drainage : deep venous

system ; internal cerebral veins - basal vein of Rosenthal - great vein of galen

TOXIC POISONING• CAUSE : MC - CO , methanol and CN• Impairs mitochondrial enzyme in electron transport chain .• CLINICAL FEATURES : Acute cognitive impairment /coma , optic

neuritis (methanol) DIAGNOSIS• Toxicology and Lab tests , imaging ( assess brain damage)

TOXIC POISONINGIMAGING FINDINGS• CO – GP(MC) : T1 & T2 hyperintense + DWI RD , Delayed

leukoencephalopathy • CN , Meth : Hemorrhagic necrosis of putamen• Meth : White matter edema

LIVER DISEASE• CAUSATIVE AGENT : Due to nitrogenous waste crossing BBB• CLINICAL FEATURES : cirrhosis with portal htn /iatrogenic (TIPSS)• IMAGING FINDINGS : - GP and SN : hyper on T1( due to Mn deposn) - Reversible post transplantation. - Acute hyperammonemia : bilaterally symmetric swelling, T2 prolongation restricted diffusion in the basal ganglia, insular cortex, and cingulate gyrus - MRS : Detection of glutamate-glutamine

NON KETOTIC HYPERGLYCEMIA• CLINICAL FEATURES : poorly controlled diabetes with chorea ,

hemiballismus +/- altered mental status.• Treatable condition which shows resolution of findings when

performed 2-12 months laterIMAGING FINDINGS⁻ CT: B/L or rarely U/L hyperattenuation of GP or CN⁻ MR : hyperintensity on T1 and variable intensity in T2

HYPOGLYCEMIA• CLINICAL FEATURES : Diabetic pts, Seizures , focal neurological

deficits and coma.• Extent of brain damage depends on severity and duration of

hypoglycemia.IMAGING FINDINGS:• T2 hyperintensity in cerebral cortex , hippocampi and BG• Mild reversible hypoglycemia – transient and isolated WMI with true

diff restriction involving splenium , internal capsule and corona radiata.

• BG INVOLVEMENT : POOR PX

HYPOXIC ISCHEMIC ENCEPHALOPATHY• CAUSE : Result of cardiac arrest /drowning/asphyxiationIMAGING FINDINGS: • Mild HIE : water shed zones• Severe HIE : grey matter structures like cerebral cortex , BG and hippocampi.

• Brainstem and WM are typically spared.

• CT : Diffuse edema , decreased attenuation of the cortical gray matter with loss of normal gray matter–white matter differentiation, BG and Thalamus

• WHITE CEREBELLUM SIGN : diffuse cerebral damage results in lower attn. of cerebral parenchyma , compared to cerebellum and BG which are spared – POOR PX

HYPOXIC ISCHEMIC ENCEPHALOPATHY• Earliest finding(after 2 hrs) : Increased SI of the affected areas on

DW• T2W : hyperintensity and swelling of affected areas ( after 24 hrs) • Delayed : T2 hyperintensity in subcortical WM

LEIGH DISEASE• Subacute necrotizing encephalopathy• CAUSE : Disorder in ATP synthesis at ETC• CLINICAL FEATURES : Central hypotonia , developmental

regression/arrest , ophthalmoplegia , resp and bulbar dysfunction and ataxia.

IMAGING FINDINGS: • T2 hyperintensity in BG , periaquedeuctal region , cerebral peduncles

and putamen.• MRS : High lactate levels in BGDIAGNOSIS : Imaging + Elevated serum and CSF lactate levels.

WILSON DISEASE• CAUSE : Accumulation of Cu due to ceruloplasmin deficiency.• CLINICAL FEATURES : dysarthria, dystonia, tremors, ataxia,

Parkinsonian symptoms, and psychiatric problems.IMAGING FINDINGS: • MR : T2 hyperintensity in Putamen(MC)• GP , caudate nucleus , thalamus• Less common : cortical and subcortical region , mesencephalon , pons , vermis

and dentate nuclei• DWI restriction in early stages

OSMOTIC MYELINOLYSIS• CAUSE : electrolyte imbalance, chronically alcoholic pts, chronically

debilitated organ transplant pts , rapid overcorrection of hyponatremia.

• Oligodendroglial cells are more susceptible to osmotic stresses.

OSMOTIC MYELINOLYSISIMAGING FINDINGS:• MRI : T1 and T2 hyperintensity in affected areas• Central pontine myelinolysis : Symmetric trident shaped / bat wing

shaped T2 /FLAIR hyperintensity in central pons • Ventrolateral pons and pontine portion of CST are spared

• Extrapontine myelinolysis : T2 hyperintensity in GP , putamen , thalamus and cerebellum.• DWI R in early stages – not typical though

DIAGNOSIS : Imaging + serial Na measurement

WERNICKE ENCEPHALOPATHY• CAUSE: Vit B1 def , Chronic alcoholics , GI or hemat neoplasm ,

chronic dialysis , prolonged TPN without vit supplementation.• CLINICAL FEATURES : altered consciousness, ocular dysfunction, and

ataxiaIMAGING FINDINGS: • MRI : Symmetric T2 hyperintensity in medial thalamus ,

periaqueductal area , mammillary body and tectal plate. • Petechial hemorrhage , diffusion restriction and contrast

enhancement of affected areas

NEURODEGENERATION WITH BRAIN IRON ACCUMULATION (NBIA)• Heterogenous group of disorder with brain degeneration and

excessive iron deposition in basal ganglia(PAN K 2 gene mutation.)• 2 types • Classic early onset , rapidly progressive(halloverden spatz)• Atypical late onset and slowly progressive

• CLINICAL FEATURES : pyramidal or extrapyramidal signs, dystonia, and dysarthria

IMAGING FINDINGS: • MR : B/L T2 hypointensity in GP with high signal intensity center -

EYE OF THE TIGER appearance

Creutzfeldt –jakob Disease• Transmissible fatal neurodegenerative disorder caused by prions• CLINICAL FEATURES : rapidly progressive dementia, myoclonus, and

multifocal neurologic dysfunction.• DIAGNOSIS: Brain Biopsy /autopsy, periodic charp wave complexes

at EEGIMAGING FINDINGS: • MRI : DWI R of cerebral cortex and basal ganglia• Variant CJD : Bovine spongiform encephalopathy • B/L lesions in pulvinar nuclei of thalamus(pulvinar sign/hockey stick sign)

FAHR DISEASE• Bilateral striopallidodentate calcinosis• B/L symmetric deposition of Ca and other minerals in BG ,Thalamus ,

Dentate nuclei and centrum semiovale in absence of HYPOPARATHYROIDISM.

• CLINICAL FEATURES : Headache , vertigo , movt disorders , syncope , seizures , coma, dementia , parkinsonism , chorea, dystonia etc.

IMAGING FINDINGS: • MRI/CT : B/l symmetric dense calcifications in BG , dentate nuclei ,

thalamus , subcortical white matter .

DEEP CVT• CAUSE : hypercoagulable states , OCPS , vasculitis , intracranial / systemic infectionsIMAGING FINDINGS: • Superficial CVT: cerebral edema and venous infraction of cerebral

cortex near vertex.• Deep CVT: Venous HTN , b/L involvement of thalamus and basal ganglia.• MRI/CT: Venous HTN and cerebral edema results in T2 hyperintensity

in thalamus , BG , internal capsule and DWM • Hemorhhagic transformation common

• MR venogram : evaluation of thrombus

ARTERIAL OCCLUSION • CLINICAL FEATURES : Agitation , obtundation , coma , memory

dysfunction and various ocular changesIMAGING FINDINGS: • Acute infarcts : T2 hyperintensity and DWI R with occlusion seen on

MRA based on the artery occluded.• Artery of Percheron infarct : B/l symmetric paramedian parts of

thalamus and midbrain on both sides.

Figure 19. Basilar artery occlusion in a 61-year-old man with ocular signs and severe obtundation. (a) Diffusionweighted MR image shows bilateral hyperintense areas in the paramedian thalamus (arrows). (b) Timeof- flight MR angiogram clearly depicts occlusion of the rostral portion of the basilar artery (arrow). (c, d) Noncontrast CT scans obtained 3 days later show bilateral subacute infarcts of the thalamus (arrows in c) and an infarct in the right cerebellar hemisphere(arrow in d).

NEURO – BEHCET DISEASE• Behcet syndrome : uveitis , oral ulcers and genital ulcers.• CNS involvementin 4-49%• CLINICAL FEATURES : Headache , dysarthria , cerebellar signs ,

sensory signs and personality change.IMAGING FINDINGS: • T2 hyperintense and T1 hypointense and CE with vasogenic edema

at brainstem, basal ganglia (bilateral involvement in one-third of cases), and thalamus , WM(LC)

FLAVI VIRUS ENCEPHALITIS• Eg : Japanese encephalitis, West nile fever , Murray valley feverIMAGING FINDINGS: • Symmetric involvement of deep grey matter JE : T2 hyperintensity in B/L posteromedial thalamus

• Intralesional hemorrhages + DWI R• Less common sites : basal ganglia, substantia nigra, red nucleus, pons, hippocampi,

cerebral cortex, and cerebellum.

• JE and Murray valley fever involve THALAMUS• West nile fever : B/L involvement of thalamus , caudate and lentiform nucleus

CEREBRAL TOXOPLASMOSIS• CAUSE : Toxoplasma gondii typically in imuncompromised ptsMAGING FINDINGS: • Multiple focal lesions in the basal ganglia and lobar gray matter–

white matter junctions• T2 W : hypo to isointense lesions with prominent mass effect and

vasogenic edema +/- hemorrhagic lesions• Post Contrast : nodular/ ring enhancement• MRS : increased lipid levels without elevated choline levels

PRIMARY CNS LYMPHOMA• CAUSE : immunocompetent and immunocompromisedIMAGING FINDINGS: • T2 hypointensity and high attenuation in CT involves deep

hemispheric periventricular white matter, corpus callosum, and basal ganglia

• MRS : Elevated choline levels• Immunocompetent : Solid, homogeneously enhancing lesions• Immunocompromised : Ring enhancement and central necrosis

PRIMARY BILATERAL THALAMIC GLIOMA• Thalamus is affected in 1-1.5% of brain tumors / contiguous spread

from pineal germ cell tumors.• CLINICAL FEATURES : behavioral impairment ranging from

personality changes to dementia. • IMAGING : T2 hyperintense and T1 isointense B/L symmetric mass

with no CE • Low grade tumors characterized by absence of tumor progression

on serial MR images,

NEUROFIBROMATOSIS TYPE I• MC neurocutaneous syndrome• CLINICAL FEATURES : café-au-lait spots, axillary freckling, Lisch

nodules, neurofibromas, plexiform neurofibromas, optic glioma, bone dysplasias, or pseudoarthrosis.

IMAGING FINDINGS: Focal T2 hyperintense and TI hypointense in GP > brainstem and cerebellum• NO mass effect• No surrounding edema• No CE

• MRS : high NAA-Ch , Naa-Cr and Cr- Cho ratios

IMAGING

LAB IXCL.HISTORY

DX

LAB EVALUATIONImmunoassay Toxoplasmosis and Flavivirus

Eeg + CSF analysis CJD

Vit B1 assay Wernickes

Serum glucose Hypoglycemia/Hyperglycemia

Serum Ceruloplasmin Wilsons disease

Serum and CSF Lactate Leigh Disease

Serum Ca , P and PTH Fahrs DIsease

IMAGING

LAB IXCL.HISTORY

DX

• CLINICAL HISTORY • Suicide attempt • cardiac arrest • diabetic hypoglycemia • hyperglycemia • Hiv – AIDS • Vit deficiency • Electrolyte imbalance

IMAGING

LAB IXCL.HISTORY

DX

IMAGING FINDINGS

B/L symmetric LN andCN Systemic /metabolic

Asymmetric focal/Discrete Infection/neoplasm

Thalamus+ BG Hypoxia , osmotic myelinolysis , wilsons disease , Leighs disease , Fahrs disease , CJD , deep CVT, Infection , Primary CNS lymphoma

BG w/o Th Systemic disease ( toxic poisoning , hypoglycemia , hyperglycemia , liver disease , huntingtons disease , NF)

B/L Th w/o BG Focal ( arterial occlusion ,Flavivirus , infection )

ASSOCIATED ABNORMALITIES

Diffuse or focal cortical involvement Hypoxia , hypoglycemia and CJD

Diffuse and bilateral white matter abnormality

poisoning , hypoglycemia

Brainstem Leigh disease , Myelinolysis , Neuro behcets disease , Basilar artery occlusion

Perilesional edema + infiltration outside BG + Th

CNS infection + tumors

ASSOCIATED ABNORMALITIEST2W HYPERINTENSITY Acute diseases of deep grey

matter nuclei T1W HYPERINTENSITY Hepatic dis , Mn deposition ,

Hyperglycemia , NF 1

CT Ca – Fahrs disease, HypoparathyroidismH’age – Poisoning, CNs toxoplasmosis, Venous infarction , JE

DWI Acute cytotoxic brain damage in acute infarction, hypoxia, hypoglycemia, CJD,and Wernicke encephalopathy

MRS lactate in hypoxia or mitochondrial disease