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Huntington's Chorea P011

Document
Last amended 
30 June 2015
Current RMA Instruments:
Reasonable Hypothesis SOP
37 of 2015
Balance of Probabilities SOP
38 of 2015
Changes from Previous Instruments:

SOP Bulletin 179

ICD Coding:
  • ICD-9-CM Codes: 333.4
  • ICD-10-AM Codes: G10

This is a genetic disorder of the nervous system, progressively manifesting with a movement disorder (chorea) and then cognitive dysfunction and neuropsychiatric disorder.

Is specific diagnostic evidence required to apply the SOP? - Yes.

This diagnosis is based on specialist neurologist opinion with recourse to MRI [magnetic resonance imaging] scan of the brain and spinal cord and genetic testing.

Are there sub-factors that require specific information? – No.

The only factor is for clinical worsening from inability to obtain appropriate clinical management. It is difficult to ascertain a clinical worsening given the progressive nature of the disorder. See notes below.

Diagnoses covered by SOP
  • Nil
Conditions excluded from SOP
  • Brain and nervous pathology from other causes
  • Dementia from other causes including Alzheimer's disease
  • Psychiatric disorders from other causes
Unconfirmed diagnosis

If, after applying the above information, you are unable to confirm the diagnosis, you should then seek medical officer advice about further investigation.

Notes on appropriate clinical management

Natural progression of the disease varies with the phenotype.  Worsening beyond the normal progression of the disease needs to be evident before a clinical worsening factor can be considered.

No cure or disease-modifying treatment is currently available for Huntington’s disease.  Therapy is focused on symptom management and supportive care in order to optimize quality of life. (1)

Symptoms of Huntington’s chorea begin insidiously with movement abnormalities and/or with psychiatric and cognitive features.  Chorea is a key feature and the defining sign at the time of diagnosis.  With disease progression, motor function slowly deteriorates.  Chorea may eventually be replaced in advanced stages of by a parkinsonian akinetic-rigid state.  The slow but relentless deterioration in cognitive and motor function causes significant morbidity and early mortality.  Cognitive decline is inevitable.  The disease is associated with an increased risk of suicide for diagnosed patients. (2)

Footnotes:

(1) Suchowersky, O. 2014, ‘Huntington’s Chorea: Management’, UpToDate, http://www.uptodate.com/contents/huntington-diseas...

(2) Suchowersky, O. 2014, ‘Huntington’s Chorea: Clinical features and diagnosis’, UpToDate, http://www.uptodate.com/contents/huntington-diseas...