0:00

We're here with our 67-year-old man with

0:03

late-onset Huntington's chorea.

0:06

And on this coronal FLAIR,

0:08

he manifests many of the imaging features of HC,

0:13

namely Sylvian atrophy, frontal,

0:17

generalized frontal atrophy,

0:18

especially in the anterior Sylvian projections,

0:21

some sub frontal atrophy,

0:23

and then generalized parietal temporal atrophy,

0:26

although the temporal component of the atrophy is

0:29

less conspicuous than the other components,

0:31

unlike ALZ and its variants,

0:34

where the temporal component is more conspicuous.

0:36

Now, a range of 27 to 35 cytosine adenine guanine

0:41

repeats or CAG repeats is considered normal.

0:44

But there's a particular risk of expansion of

0:48

Huntington's disease into the Huntington's range

0:51

in the paternal germ line.

0:53

So, with each successive progeny on the male side

0:57

the number of CAG repeats may increase.

1:00

So, the disease may become more penetrant

1:03

and more severe

1:05

as each generation continues onward.

1:07

Carriers of the mutated Huntington's disease gene

1:11

typically first develop symptoms in

1:13

their mid-thirties or forties.

1:14

But the age of onset for Huntington's disease varies

1:17

from early childhood to the 70's

1:19

and even into the 80s.

1:21

So, old age does not preclude this as a diagnosis.

1:24

The onset of Huntington's disease before age

1:27

20 is known as the Westfall variant.

1:30

It's strongly associated with a very high number

1:33

of CAG repeat lengths in mutated Huntington's

1:37

disease genes, usually greater than 55,

1:41

whereas association between CAG

1:43

or cytosine adenine guanine repeat length

1:46

and age of onset is in the

1:48

range of 40 to 50 repeats in weak presentations

1:53

of Huntington's disease.

1:54

Now, the full spectrum of motor impairment in

1:56

Huntington's disease includes

1:58

eye movement abnormalities,

1:59

which can sometimes simulate

2:01

clinically progressive supranuclear palsy

2:05

Parkinson's features and dystonia,

2:07

which can particularly simulate

2:10

Parkinson's syndromes.

2:12

You see Parkinson features and dystonia,

2:15

particularly in juvenile Huntington's disease

2:18

before age 20,

2:19

myoclonus, ticks, ataxia, dysarthria,

2:23

dysphasia, spasticity with hyperreflexia,

2:27

as well as extensor plantar responses.

2:30

With progressing illness,

2:32

chorea is commonly superseded by dystonia.

2:36

This sort of rigid,

2:38

Parkinsonian-like presentation where the patient

2:40

will have a movement and then

2:42

freeze in that movement.

2:44

And often these movements are natural movements,

2:46

like reaching or touching the face,

2:48

and then the patient is stuck in that position.

2:51

Huntington's disease is broad and includes

2:54

obsessive-compulsive symptoms

2:56

on the psychiatric side,

2:57

mania, psychosis, irritability, aggressive behavior,

3:02

sexual disinhibition and apathy.

3:06

It's a relentless, progressive disease.

3:08

Usually, the survival is about 15 to 20 years

3:12

after the onset of symptoms,

3:13

and some atypical antipsychotics may be used

3:16

to try and control some of these symptoms.