04 March 2017

Huntington Disease

10 years old boy from parents being cousins to each other presents with progressive rigidity and dystonia. Initial MR showing significant bilateral atrophy in caudate nuclei and putamina with high signal on FLAIR and T2 consistent with gliosis.

Note striking symmetric atrophy of the putamina and caudate nuclei on T2 and IR.

Huntington disease (HD) is also known as Huntington chorea. HD is an autosomal dominant chronic hereditary neurodegenerative disorder with complete penetrance [Osborn]. 

Aggregates of huntingtin protein accumulate in axonal terminals, which eventually leads to the death of medium spiny neurons. Autopsy shows generalized cerebral atrophy with an average of 30% reduction in brain weight. Both the cortex and hemispheric WM are affected. The most characteristic gross abnormality is volume loss with rarefaction of the caudate nucleus, putamen, and globus pallidus [Osborn]. 

Microscopically, HD features neuronal loss with huntingtin nuclear inclusions, astrocytic gliosis, and iron accumulation. The changes are most severe in the basal ganglia but can also be seen in other regions of the brain, including the cerebellum [Osborn].

Juvenile-onset HD is initially characterized by rigidity and dystonia, much more than by chorea [Osborn].

26 February 2017

Intracranial Hypotension with Dural Sinus Thrombosis

Contrast enhanced T1 sequences showing large thrombi in the posterior parts of the superior sagittal sinus (SSS). However note that this young female patient in postpartum period is also presenting with classical signs of Intracranial Hypotension. There is general dura enhancement, swelling of hypophysis and slight sagging of the cerebellum. 

Transversal SWI and T2 show thrombus in SSS and swelling of the cortical veins. 

Sagittal and transversal FLAIR sequences show thrombus with higher signal that is obstructing (black ) flow-voids in SSS. 

It is believed that Intracranial Hypotension (that is most often caused by CSF leakage) is the reason for slowing down the venous blood flow in the dural sinus. However note that Dural Sinus Thrombosis (DST) is a very seldom complication of Intracranial Hypotension (2%). Most often does DST manifest as Intracranial Hypertension (20-40%).

Check my previous cases:
CSF Leakage - Intracranial Hypotension
Intracranial Hypotension
CSF Leakage Spine - MRI Protocol
Idiopathic Intracranial Hypertension

Capillary Telangiectasia

Classic case of an incidental finding of a small Capillary Telangiectasia in the pons. Note low signal on SWI and diffuse subtle contrast enhancement on T1. Location is very typical but other locations are common. 

On T2 this small Capillary Telangiectasia is hardly visible, without any signs of oedema. There is a blush of enhancement on T1C+ coronal image. 

Carbon Monoxide Poisoning - infarctions in globi pallidi

82 years old admitted with signs of intoxication, history of suicide attempt. NECT shows symmetric low density oedematous globi pallidi (GP) - compared to old CT.

Note low density in globi pallidi on the admission NECT compared to old CT. 

MR exam has shown diffusion restriction in globi pallidi (high signal in GP on this rather dark DWI and low signal on ADC) corresponding with acute infarctions.

FLAIR and T2 show oedema in globi pallidi corresponding with acute infarctions. 

Contrast enhanced T1 sequence (right) shows a very subtle enhancement in both globi pallidi consistent with blood-brain barrier damage. 

20 February 2017

Herpes Simplex Encephalitis

6 months old child diagnosed with Herpes Simplex Encephalitis (HSE). CT showing low density areas in both temporal lobes. This finding is difficult on CT due to artefacts often present in middle cerebral fossa. Clue here is the coronal reconstruction showing low density in the lower parts of the basal ganglia.

MR in acute phase confirms diffusion restriction bilateral in the lower parts of the basal ganglia as well as oedema seen on T2.

T2 and FLAIR show diffuse oedema in the lower parts of basal ganglia on both sides. 

Follow up MR about 3 months later showing on FLAIR and T1 extensive atrophy and gliosis in the temporal lobes. 

Axial SWI showing extensive hemorrhagic changes (hemosiderin) in the HSE damaged regions. Note extensive encephalomalacia involving temporal lobes and lower parts of basal ganglia.

Teaching point here is to have an extra careful look at CT images that are mostly performed as first line of examination, especially look for oedema and low density in both temporal lobes, lower parts of basal ganglia and the limbic system. It is recommended to perform MR study for further diagnosis. In older patients infarction is the main differential diagnosis. HSE is mostly bilateral and often asymmetric.