Vit B12 deficiency MRI brain findings

Clinically young female with psychiatric complaints like altered behaviors and generalized weakness.

MRI FLAIR images of brain shows bilateral fronto parietal and temporal peri ventricular confluent T2 hyper intensities. DDs given were Viral encephalitis like HIV encephalitis, ADEM, Toxic Metabolic encephalopathy. MRI screening of spine shows no obvious spinal cord involvement.

Lab report showed significantly low level of Vit B12 suggestive of isolated brain involvement in B12 deficiency. Patient improved with Vit B12 supplements.

Vitamin B12 deficiency 

Vitamin B12 or Cobalamin deficiency causes a wide range of hematological, gastrointestinal, psychiatric and neurological disorders.

Neuropsychiatric symptoms may precede hematologic signs and are represented by myelopathy, neuropathy, dementia and visual loss due to optic nerve atrophy. 

Causes 

A strict vegetarian diet contains very little cobalamin. There is clear evidence of abnormal cobalamin metabolism in vegetarians and hyper-homocysteinemia is a risk factor, especially for stroke and vascular dementia, vegetarians are advised to take cobalamin supplements lifelong.

In developed countries, the diet is rich in meat and cobalamin-rich foods; thus, malabsorption is the most common cause of cobalamin deficiency. 

Infants born to vegetarian mothers are at risk of cobalamin deficiency and may present with megaloblastic anemia.

Clinical and Hematological Manifestations ranges from incidental increased mean corpuscular volume and neutrophils hypersegmentation in otherwise asymptomatic patients to symptoms due to severe anemia, such as angor, dyspnea on exertion, fatigue or symptoms related to congestive heart failure, such as ankle edema, orthopnea and nocturia. 

Neuroimaging

Vitamin B12 deficiency may affect both the central (brain, spinal cord and optic nerve) and the peripheral (peripheral nerves) nervous system.

The spinal cord involvement is associated with the most frequent manifestation of vitamin B12 deficiency, namely subacute combined degeneration (SCD), is characterized by symmetric dysesthesia, disturbance of position sense and spastic paraparesis or tetraparesis. The most consistent MRI finding is a symmetrical abnormally increased T2 signal intensity, commonly confined to posterior columns in cervico dorsal spinal cord ' inverted V' configuration. 

Isolated brain involvement has also been reported in B12 deficiency but is rare in adults. 

MRI shows confluent T2 high-intensity signal in periventricular white matter.

Isolated brain involvement is common in children with inherited cobalamin-related diseases characterized by white matter loss with delayed myelination.

In infants with nutritional cobalamin deficiency MRI has revealed delayed myelination.

Therapy is definitely Vitamin B12 supplements oral or intra muscular.