Marchiafava Bignami Disease MRI

A chronic alcoholic brought unconscious. On admission MRI axial FLAIR shows T2 hyper intensity confined to corpus callosum with restricted diffusion on Dw images. 

Marchiafava Bignami Disease

A rare toxic disease that results in progressive demyelination and necrosis of the corpus callosum.

Mostly seen in chronic alcoholics but occasionally seen in non alcoholics.

Believed to be mainly due to deficiency of Vitamin B complex as many improve with Vit B supplementation but some may not.

At first, MB was thought to be particular to individuals living in the central region of Italy and consuming large amounts of inexpensive Chianti red wine. It is now known that MB occurs worldwide with all other alcoholic beverages too.
Most males, between 40 and 60 years of age with history of chronic alcoholism and malnutrition.

Diagnosis is made on the basis of clinical findings in combination with imaging.
Acute MB patients present with mental confusion, disorientation, neurocognitive deficits, and seizures. Most of them go into coma and eventually die. Acute MB may be difficult to distinguish from Wernicke encephalopathy and may occur together. Patients with Wernicke encephalopathy have ataxia, ophthalmoplegia, nystagmus, and confusion. 

Subacute form of MB is characterized by dementia, disarthria, and muscle hypertonia—may survive for years. 

Chronic form of MB is characterized by a chronic dementia and now differentials includes Alzheimer disease, multi-infarct dementia, and Pick disease.

On MRI, MB show high T2 and FLAIR signal intensity, typically affects the body of the corpus callosum, followed by the genu, and finally the splenium. The entire corpus callosum may be also involved. May extend to adjacent white matter tracts such as the anterior and posterior commisures and the cortico-spinal tracts. The corpus callosum degenerates and splits into three layers - “layered necrosis”. The reason of predilection for corpus callosum is not known.
The lesions are difficult to visualize on CT.

On MR spectroscopy mildly increased choline level (probably secondary to acute demyelination), low N-acetyl aspartate (probably secondary to neuronal damage), and the presence of lactate. 

Other lesions showing restricted diffusion in corpus callosum include infarctions, shearing injuries, demyelination and Encephalitis.
Differentiating acute MB from Wernicke encephalopathy on imaging is not difficult; WE shows abnormal signal intensity and contrast enhancement in the mamillary bodies, periaqueductal region and the walls of the third ventricle. 

Reference: Acute Marchiafava-Bignami Disease: MR Findings in Two Patients, Andres Arbelaeza, Adriana Pajona and  Mauricio Castillob; AJNR 2003 24: 1955-1957

Restricted diffusion in Splenium of Corpus Callosum

A 18 yo male, known case of GTCS under treatment with anti epileptic drugs (which drug i am deliberately not mentioning), comes now with very recent history of seizure, at the time of admission conscious and well oriented.
Vitals normal.
No neurological signs.
No fall or significant head injury during seizure episode.
No any cardio pulmonary resuscitation required.
Immediate post admission MRI Brain done show a focal restricted diffusion in the region of splenium of corpus callosum.

Rest of the brain parenchyma normal.
Csf evaluation done turned out normal.
Managed conservatively, continued the same AEDs and discharged.

Discussion about the case: 

Differentials for Splenial signal abnormality are Ischemia, Diffuse axonal injury, Multiple sclerosis, Marchiafava-Bignami disease, Wernicke's encephalopathy , Encephalitis, Post ictal and long term antiepileptic drug usage.

Now in this case we’ll rule out one by one to cut short the list of differentials. 

• Ischemia is unlikely as pt was stable, vitals were normal. No history of cardiac arrest or cardio pulmonary resisutation.
• Diffuse axonal injury unlikely as there was no history of significant trauma. Pts was not unconscious, Glass-Glow Coma score.
• Multiple sclerosis unlikely as there were no plaques elsewhere.
• For Marchiafava-Bignami disease patient is non alcoholic.
• Wernicke's encephalopathy (WE) caused by profound vitamin B1 (thiamine) deficiency and commonly presents with the classic clinical triad of mental confusion, ataxia, and ophthalmoplegia.
• Encephalitis, yes milder form of encephalitis is possible and mentioned in literature with reversible restricted diffusion in SCC. ( Reference: American Journal of Neuroradiology 27:1983-1986, October 2006)
• Long term use of Antiepileptic drungs, may be, as mentioned in most of the literature as possible cause for restricted diffusion in SCC which also mentions that it reverses with discontinuation of AEDs. But there are certain literatures reports presence of restricted diffusion in SCC in patients not using AEDs (reference: Epilepsia, 44(6):1–3, 2003, Blackwell Publishing, Inc.C 2003 International League Against Epilepsy) which support that it is related to seizure activity itself and not the result of long term use of AEDs, Drug toxicity or Demyelination. They also mention that it’s a transient signal abnormality with intramyelinic vasogenic edema as possible mechanism.

So the post ictal transient signal abnormality appears to be the most convincing.

A follow up MRI after 1 month showed complete regression of the signal abnormality again supports that the signal abnormality which was seen in splenium of corpus callosum is a reversible signal abnormality and can be correlated to seizure activity itself and not the result of use of AEDs.