Non-parkinsonian Movement Disorders: Chorea and Huntington’s Disease

00:01 Now let's talk about Chorea.

00:03 Chorea is defined as a hyperkinetic movement disorder so there's extra movement characterized by involuntary, brief, random and irregular contractions conveying a feeling of restlessness to the observer.

00:16 These people just move around.

00:17 Sometimes they look like they're dancing, sometimes they can't get still in their chair.

00:22 They appear restless and are constantly in some source of movement.

00:30 In terms of clinical manifestations, this is a brief movement that is irregular with contractions that are not repetitive or rhythmic, and they appear to flow from one joint to the next as the movement moves throughout the body.

00:44 It can give the appearance of a dance like pattern or an internal restlessness where patients continue to move.

00:51 There can also be associated movement disorder symptoms.

00:55 We can see motor impersistence in these patients and that's the inability to perform a sustained motor activity.

01:02 And some manifestations of that include the milkmaid's grip.

01:05 This is uncontrollable rhythmic squeezing of the examiners fingers when trying to grip.

01:10 It's a motor impersistence.

01:12 The examiner asked the patients to grip but they can't keep a grip.

01:15 So it results in this squeezing appearance.

01:18 We can see in a Jack-in-the-box tongue when patients are asked to protrude the tongue, it cannot be maintained out.

01:25 And so the tongue continually retracts back into the mouth and is protruded out and so that Jack-in-the-box tounge is a symptom of motor impersistence.

01:35 And then Choreiform gait so as patients walk they appear to have a dance like appearance of their gait, and this is suggestive of a chorea form disorder.

01:45 We can classify chorea as either primary or secondary.

01:49 Primary chorea's are idiopathic, they're often genetic in origin.

01:52 There's not a cause, they just develop as a result of some internal primary CNS disorder.

01:59 And the types of disorders where we can see primary chorea.

02:02 The most common and classic is Huntington's disease.

02:05 But we can see this with Huntington's disease-like syndromes, dentatorubral-pallidoluysian atrophy, benign hereditary chorea and Wilson's disease.

02:16 That differs from secondary choreas which is where chorea is related to infectious, immunologic or other medical causes.

02:24 And we can see this in Sydenham's chorea, drug-induced chorea, immune mediated chorea's, infectious choreas and vascular disorders that can contribute to chorea.

02:35 Sydenham's chorea is particularly interesting.

02:37 It can be seen in young children.

02:39 This is chorea that develops after a strep infection.

02:42 And it's a delayed effect of abnormal movement disorder circuitry where patients develop chorea after that infection.

02:51 Let's talk a little bit about Huntington's disease.

02:53 This is the classic syndrome where we associate chorea.

02:57 It's one of the most common causes of chorea.

02:59 It's an autosomal-dominant disorder with 100% penetrance.

03:03 It is a trinucleotide repeat disorder and so patients develop progressive lengthening of this aspect of the genes.

03:13 The age of onset is around 40 years, 5% may have juvenile onset at less than 20 years, and 30% late onset greater than 50 years of age.

03:23 Again, this is a clinical diagnosis.

03:25 We don't use imaging, but we can see imaging findings that are supportive of this diagnosis particularly late in the disease.

03:32 And the classic finding on imaging is caudate atrophy which you see here.

03:36 And it results in this appearance of boxcar ventricles.

03:39 You can see a normal ventricular system on the right where we see the prominent caught aid head butting into the lateral ventricles and this is lost in the patient on the left with Huntington's disease.

03:52 We see three types of symptoms, clinical features in patients with Huntington's disease.

03:56 It's a movement disorder, so we can see chorea and that's the prominent main phenomenology in adults, but it may not be seen in children.

04:05 We can also see dystonia, myoclonus and ataxia.

04:08 We also see cognitive impairment which is important.

04:11 This presents as a subcortical dementia, difficulty with fluency and speed of thought, impaired frontal executive function, disinhibition, short term memory impairment may also develop.

04:21 And then prominent neuropsychiatric features and these can be particularly debilitating and difficult to treat.

04:27 Depression, suicidality, anxiety, irritability, apathy, just not caring and aggression.

04:33 We also can see eye movement abnormalities, delayed initiation of saccades, and impaired anti saccade task.

04:40 The problem here is atrophy and degeneration of the caudate.

04:43 Caudate is important in both motor, cognition and mood and we see symptoms in each of those domains.

04:50 Symptoms develop, again around age of 50.

04:53 But there is genetic anticipation where symptoms develop earlier and earlier as this disease is passed from one generation and to the next.