I think that many clinicians have made some fundamental incorrect conclusions about the use of SNOMED CT in clinical practice. In particular, as SNOMED CT is touted as a replacement for Read codes, widely used in general practice in the UK, it is easy to conclude that SNOMED CT adds complexity and redundant codes without adding any other value.

I have written a short introduction on SNOMED CT in my data standards blog post.

I would like you to understand and appreciate the benefit of the structure of SNOMED CT. To do this, I’m going to give a simple example of how we can leverage the structures built into SNOMED CT to create something useful.

SNOMED CT structure

Fundamentally, SNOMED-CT is broken down into three entities - “Concepts”, “Descriptions” and “Relationships”. A concept represents a concept, which might be a clinical diagnosis, an occupation, a pharmaceutical product or anything else really. Concepts may be simple “multiple sclerosis” or represent compound terms “family history of multiple sclerosis”. Each concept has a number of “Descriptions”, one of which is the preferred term for that language and the others synonyms for that term.

It is in the “Relationships” that I shall focus today. Relationships link concepts in a directional manner. However, the type of relationship is also a concept. I have shown this diagrammatically:

Snomed Relationship Structure

This means that multiple sclerosis IS-A type of demyelinating disease.

Now there are many practical uses of such a structure. One simple use is to understand the types of patients who present to your emergency department. You can iterate through the episodes of care, asking SNOMED-CT to tell you whether the final diagnosis was, for example, a type of respiratory illness.

To demonstrate the utility of the relationship structure within SNOMED CT, I would like to introduce the solution to a new problem:

Can we allow free-text searching of unstructured clinical documents for specific diagnoses, including synonyms of that diagnosis?

So what I want to do is allow the user to type, say “MI” and return documents that contain that concept. The simple option is to free-text search for “MI” but that won’t catch documents containing the text “myocardial infarction” or “heart attack”. Can we use the relationships within SNOMED CT to do this?

Yes you can, and I implemented this a few years ago.

The solution is:

  1. Search for synonyms matching the user entered term (e.g. “MI”). This should return diagnostic concepts matching myocardial infarction but also mitral valve incompetence.
  2. For each synonym, find the concept. For each concept, optionally also find concepts that are equivalent “child” concepts, recursively walking the IS-A relationship tree.
  3. For each concept, return all of the descriptions.

An example can be found here, hitting a live SNOMED CT REST terminology server.

You should end up with JSON with your results:

{
  "data": [
    "Heart attack",
    "Cardiac infarction",
    "Infarction of heart",
    "Myocardial infarction",
    "Myocardial infarct",
    "MI - Myocardial infarction",
    "MI - Mitral incompetence",
    "Mitral regurgitation",
    "Mitral valve insufficiency",
    "Mitral valve incompetence",
    "Mitral valve regurgitation",
    "Mitral insufficiency",
    "MR - Mitral regurgitation",
    "Acute myocardial infarction",
    "AMI - Acute myocardial infarction",
    "Coronary thrombosis not resulting in myocardial infarction",
    "MI - Myocardial infarction aborted",
    "Aborted myocardial infarction",
    "MI - Silent myocardial infarction",
    "Silent myocardial infarction",
    "NSTEMI - Non-ST segment elevation MI",
    "Acute non-ST segment elevation myocardial infarction",
    "Acute ST segment elevation myocardial infarction due to left coronary artery occlusion",
    "Acute ST segment elevation MI (myocardial infarction) due to left coronary artery occlusion",
    "Acute ST segment elevation myocardial infarction due to right coronary artery occlusion",
    "Acute ST segment elevation MI (myocardial infarction) due to right coronary artery occlusion"
  ],
  "total": 26
}

If I turn on support for returning synonyms of child concepts as well, then we end up with a very comprehensive list of search terms:

{
  "data": [
    "Acute myocardial infarction of basal-lateral wall",
    "Rheumatic mitral stenosis with regurgitation",
    "Rheumatic mitral stenosis with incompetence",
    "Rheumatic mitral stenosis with insufficiency",
    "Healed coronary",
    "Old myocardial infarction",
    "Healed myocardial infarction",
    "Acute papillary muscle infarction",
    "Acute infarction of papillary muscle",
    "Acute myocardial infarction of posterolateral wall",
    "MI - Myocardial infarction",
    "Myocardial infarct",
    "Myocardial infarction",
    "Infarction of heart",
    "Cardiac infarction",
    "Heart attack",
    "Acute myocardial infarction with rupture of ventricle",
    "Mitral incompetence - rheumatic",
    "Rheumatic mitral regurgitation",
    "Rheumatic mitral incompetence",
    "Rheumatic mitral insufficiency",
    "Past myocardial infarction diagnosed on electrocardiogram AND/OR other special investigation, but currently presenting no symptoms",
    "Past myocardial infarction diagnosed on ECG AND/OR other special investigation, but currently presenting no symptoms",
    "Microinfarction of heart",
    "Microinfarct of heart",
    "MR - Mitral regurgitation",
    "Mitral insufficiency",
    "Mitral valve regurgitation",
    "Mitral valve incompetence",
    "Mitral valve insufficiency",
    "Mitral regurgitation",
    "MI - Mitral incompetence",
    "Acute anteroapical myocardial infarction",
    "Acute anteroapical infarction",
    "Acute anterior myocardial infarction",
    "Acute myocardial infarction of anterior wall",
    "AMI - Acute myocardial infarction",
    "Acute myocardial infarction",
    "Acute lateral myocardial infarction",
    "Acute myocardial infarction of lateral wall",
    "Acute myocardial infarction of apical-lateral wall",
    "Rheumatic mitral AND aortic valve regurgitation",
    "Rheumatic mitral AND aortic valve incompetence",
    "Rheumatic mitral AND aortic valve insufficiency",
    "Acute anteroseptal myocardial infarction",
    "Acute myocardial infarction of high lateral wall",
    "Acute myocardial infarction of inferolateral wall",
    "Acute inferolateral myocardial infarction",
    "Acute myocardial infarction of anterolateral wall",
    "Acute anterolateral myocardial infarction",
    "Acute subendocardial infarction",
    "Acute nontransmural infarction",
    "Acute myocardial infarction of posterobasal wall",
    "Acute myocardial infarction of diaphragmatic wall",
    "Acute inferior myocardial infarction",
    "Acute myocardial infarction of inferior wall",
    "Acute inferoposterior infarction",
    "Acute myocardial infarction of inferoposterior wall",
    "Acute myocardial infarction of septum alone",
    "Acute septal infarction",
    "Acute myocardial infarction of septum",
    "Rheumatic mitral valve insufficiency AND aortic valve stenosis",
    "Postoperative myocardial infarction",
    "Mitral stenosis with insufficiency",
    "Mitral stenosis with regurgitation",
    "Mitral stenosis with incompetence",
    "Mitral incompetence and aortic stenosis",
    "Mitral regurgitation and aortic stenosis",
    "Mitral insufficiency and aortic stenosis",
    "Mitral and aortic incompetence",
    "Mitral and aortic insufficiency",
    "Mitral and aortic regurgitation",
    "True posterior wall infarction",
    "True posterior myocardial infarction",
    "Acute myocardial infarction of atrium",
    "Acute atrial infarction",
    "Aborted myocardial infarction",
    "MI - Myocardial infarction aborted",
    "Coronary thrombosis not resulting in myocardial infarction",
    "Subsequent myocardial infarction",
    "Reinfarction of myocardium",
    "Subsequent myocardial infarction of anterior wall",
    "Subsequent myocardial infarction of inferior wall",
    "Non-rheumatic mitral regurgitation",
    "Mitral incompetence, non-rheumatic",
    "Acute Q wave infarction - anteroseptal",
    "Acute non-Q wave infarction - anteroseptal",
    "Acute Q wave infarction - anterolateral",
    "Acute non-Q wave infarction - anterolateral",
    "Acute Q wave infarction - inferior",
    "Acute non-Q wave infarction - inferior",
    "Acute Q wave infarction - inferolateral",
    "Acute non-Q wave infarction - inferolateral",
    "Acute Q wave infarction - lateral",
    "Acute non-Q wave infarction - lateral",
    "Acute widespread myocardial infarction",
    "Acute Q wave infarction - widespread",
    "Acute non-Q wave infarction - widespread",
    "Acute posterior myocardial infarction",
    "Old anterior myocardial infarction",
    "Old inferior myocardial infarction",
    "Old lateral myocardial infarction",
    "Old posterior myocardial infarction",
    "Silent myocardial infarction",
    "MI - Silent myocardial infarction",
    "Mitral regurgitation due to dysfunct subvalvular apparatus",
    "Functional mitral regurgitation",
    "Prosthetic mitral valve regurgitation",
    "Acute Q wave myocardial infarction",
    "Acute Q-wave infarct",
    "Acute non-Q wave infarction",
    "Postoperative transmural myocardial infarction of anterior wall",
    "Postoperative transmural myocardial infarction of inferior wall",
    "Postoperative subendocardial myocardial infarction",
    "Non-Q wave myocardial infarction",
    "Myocardial infarction with complication",
    "Acute mitral regurgitation from chordal rupture",
    "Acute mitral regurgitation from chordal dysfunction",
    "Acute mitral regurgitation from papillary muscle dysfunction",
    "Acute mitral regurgitation from papillary muscle rupture",
    "Acute mitral regurgitation",
    "First myocardial infarction",
    "Acute ST segment elevation myocardial infarction",
    "STEMI - ST elevation myocardial infarction",
    "Acute non-ST segment elevation myocardial infarction",
    "NSTEMI - Non-ST segment elevation MI",
    "Myocardial infarction in recovery phase",
    "Mixed myocardial ischaemia and infarction",
    "Mixed myocardial ischemia and infarction",
    "Regurgitation of fetal mitral valve",
    "Regurgitation of foetal mitral valve",
    "Acute ST segment elevation myocardial infarction of anterior wall",
    "Acute STEMI (ST elevation myocardial infarction) of anterior wall",
    "Acute anterior ST segment elevation myocardial infarction",
    "Acute anterior ST segment elevation myocardial infarction with right ventricular involvement",
    "Acute STEMI (ST elevation myocardial infarction) of anterior wall with right ventricular involvement",
    "Acute ST segment elevation myocardial infarction of anterior wall involving right ventricle",
    "Prosthetic mitral valve stenosis and regurgitation",
    "Mitral prosthetic valve stenosis and regurgitation",
    "Acute prosthetic mitral valve regurgitation",
    "Acute mitral prosthetic valve regurgitation",
    "Subsequent inferior ST segment elevation myocardial infarction",
    "Subsequent ST segment elevation myocardial infarction of inferior wall",
    "Subsequent STEMI (ST elevation myocardial infarction) of inferior wall",
    "Subsequent STEMI (ST elevation myocardial infarction) of anterior wall",
    "Subsequent ST segment elevation myocardial infarction of anterior wall",
    "Subsequent anterior ST segment elevation myocardial infarction",
    "Subsequent ST segment elevation myocardial infarction",
    "Subsequent STEMI (ST elevation myocardial infarction)",
    "Acute myocardial infarction during procedure",
    "Acute periprocedural myocardial infarction",
    "Acute STEMI (ST elevation myocardial infarction) of inferior wall",
    "Acute inferior ST segment elevation myocardial infarction",
    "Acute ST segment elevation myocardial infarction of inferior wall",
    "Postprocedural mitral regurgitation",
    "Postprocedural mitral valve regurgitation",
    "Acute myocardial infarction of inferior wall involving right ventricle",
    "Acute myocardial infarction of inferior wall with right ventricular involvement",
    "Acute myocardial infarction of anterior wall involving right ventricle",
    "Acute myocardial infarction of anterior wall with right ventricular involvement",
    "Acute ST segment elevation myocardial infarction of inferior wall involving right ventricle",
    "Acute inferior ST segment elevation myocardial infarction with right ventricular involvement",
    "Acute STEMI (ST elevation myocardial infarction) of inferior wall with right ventricular involvement",
    "Mitral valve regurgitation due to cardiomyopathy",
    "Non-rheumatic mitral valve stenosis with insufficiency",
    "Non-rheumatic mitral valve stenosis with regurgitation",
    "Mitral regurgitation due to acute myocardial infarction",
    "Mitral valve regurgitation due to acute myocardial infarction",
    "Mitral regurgitation due to infiltrative disease",
    "Mitral valve regurgitation due to infiltrative disease",
    "Mitral valve regurgitation due to acute myocardial infarction without papillary muscle and chordal rupture",
    "Mitral valve regurgitation due to acute myocardial infarction with papillary muscle and chordal rupture",
    "Postprocedural mitral regurgitation due to papillary muscle and chordal damage",
    "Postprocedural mitral valve regurgitation due to papillary muscle and chordal rupture",
    "Subsequent non-ST segment elevation myocardial infarction",
    "Subsequent NSTEMI (non-ST segment elevation myocardial infarction)",
    "Acute myocardial infarction due to left coronary artery occlusion",
    "Acute myocardial infarction due to right coronary artery occlusion",
    "Acute ST segment elevation myocardial infarction involving left anterior descending coronary artery",
    "Acute ST segment elevation myocardial infarction involving left main coronary artery",
    "Acute ST segment elevation myocardial infarction of posterolateral wall",
    "Acute ST segment elevation myocardial infarction of anterolateral wall",
    "Acute ST segment elevation myocardial infarction of lateral wall",
    "Acute ST segment elevation myocardial infarction of anteroseptal wall",
    "Acute ST segment elevation myocardial infarction of posterior wall",
    "Acute ST segment elevation MI (myocardial infarction) due to left coronary artery occlusion",
    "Acute ST segment elevation myocardial infarction due to left coronary artery occlusion",
    "Acute ST segment elevation MI (myocardial infarction) due to right coronary artery occlusion",
    "Acute ST segment elevation myocardial infarction due to right coronary artery occlusion",
    "Acute ST segment elevation myocardial infarction of septum",
    "Acute ST segment elevation myocardial infarction of posterobasal wall"
  ],
  "total": 191
}

We could then use these results to maximise finding our search term in our unstructured corpus of documents.

Look what we get if we now search for “demyelinating disease”:

{
  "data": [
    "Charcot-Marie-Tooth disease, type IC",
    "Demyelinating disease of central nervous system",
    "Demyelinating disorders of the central nervous system",
    "Demyelinating CNS disease",
    "Demyelinating disease central nervous system (CNS)",
    "Central pontine myelinolysis",
    "Progressive multifocal leukoencephalopathy",
    "Multifocal leukoencephalopathy",
    "PML - Progressive multifocal leukoencephalopathy",
    "Progressive multifocal leucoencephalopathy",
    "Multifocal leucoencephalopathy",
    "PML - Progressive multifocal leucoencephalopathy",
    "PMLE - Progressive multifocal leukoencephalopathy",
    "PMLE - Progressive multifocal leucoencephalopathy",
    "Disseminated sclerosis",
    "MS - Multiple sclerosis",
    "DS - Disseminated sclerosis",
    "Multiple sclerosis",
    "Optic neuromyelitis",
    "Neuromyelitis optica",
    "Subacute myelo-optic neuropathy",
    "SMON - subacute myelo-optico-neuropathy",
    "Devic syndrome",
    "Devic's disease",
    "Charcot-Marie-Tooth disease, type IA",
    "Charcot-Marie-Tooth disease, type IB",
    "Diffuse sclerosis",
    "Schilder's disease",
    "Encephalitis periaxialis diffusa",
    "Schilder disease",
    "Acute hemorrhagic leukoencephalitis",
    "Hurst's disease",
    "Acute hemorrhagic leukoencephalitis of Weston Hurst",
    "Acute haemorrhagic leucoencephalitis",
    "Acute haemorrhagic leucoencephalitis of Weston Hurst",
    "ADEM - Acute disseminated encephalomyelitis",
    "Acute disseminated encephalomyelitis",
    "Binswanger's encephalopathy",
    "Subcortical arteriosclerotic encephalopathy",
    "Subcortical atherosclerotic dementia",
    "Chronic progressive subcortical encephalopathy",
    "Subcortical leukoencephalopathy",
    "Binswanger's dementia",
    "Encephalitis subcorticalis chronica",
    "Binswanger's disease",
    "Subcortical leucoencephalopathy",
    "Brain stem multiple sclerosis",
    "Multiple sclerosis of the brainstem",
    "Multiple sclerosis of the spinal cord",
    "Generalized multiple sclerosis",
    "Generalised multiple sclerosis",
    "Exacerbation of multiple sclerosis",
    "Multiple sclerosis (MS) exacerbation",
    "Acute relapsing multiple sclerosis",
    "Chronic progressive multiple sclerosis",
    "Multiple sclerosis (MS) chronic/progressive",
    "Remittent-progressive multiple sclerosis",
    "Multiple sclerosis (MS) remitting progressive",
    "Extrapontine myelinolysis",
    "Acute demyelinating transverse myelitis",
    "Acute non-infective transverse myelitis",
    "Subacute necrotising myelitis",
    "Subacute necrotizing myelitis",
    "Balo's concentric sclerosis",
    "Balo concentric sclerosis",
    "Concentric sclerosis",
    "Balos concentric sclerosis",
    "Chronic inflammatory demyelinating polyradiculoneuropathy with central nervous system demyelination",
    "Demyelination of spinal cord",
    "Spinal demyelination",
    "Marchiafava-Bignami disease",
    "Central demyelination of corpus callosum",
    "Marchiafava disease",
    "Hereditary sensory-motor neuropathy, type I",
    "Peroneal muscular atrophy of demyelinating type",
    "Inherited dominant hypertrophic neuropathy",
    "Hereditary motor and sensory neuropathy type I",
    "Charcot-Marie-Tooth disease of demyelinating type",
    "HSMN, type I",
    "Charcot-Marie-Tooth disease, type I",
    "Charcot Marie Tooth disease, type 1",
    "Progressive multifocal leukoencephalopathy associated with AIDS",
    "Progressive multifocal leucoencephalopathy associated with AIDS",
    "Progressive multifocal leukoencephalopathy associated with acquired immunodeficiency syndrome",
    "Progressive multifocal leucoencephalopathy associated with acquired immunodeficiency syndrome",
    "Central nervous system demyelinating disease associated with AIDS",
    "Central nervous system demyelinating disease associated with acquired immunodeficiency syndrome",
    "Secondary progressive multiple sclerosis",
    "Multiple sclerosis (MS) secondary progressive",
    "Relapsing remitting multiple sclerosis",
    "Multiple sclerosis (MS) relapsing remitting",
    "Primary progressive multiple sclerosis",
    "Multiple sclerosis (MS) primary progressive",
    "Benign multiple sclerosis",
    "Malignant multiple sclerosis",
    "Clinically isolated syndrome",
    "Vanishing white matter disease",
    "Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation",
    "LBSL - Leukoencephalopathy with brainstem and spinal cord involvement with lactate elevation",
    "Multifocal clinically isolated syndrome",
    "Polysymptomatic clinically isolated syndrome",
    "Monofocal clinically isolated syndrome",
    "Progressive multifocal leukoencephalopathy co-occurrent with human immunodeficiency virus infection",
    "Progressive multifocal leucoencephalopathy co-occurrent with human immunodeficiency virus infection",
    "Demyelinating disease of central nervous system co-occurrent with human immunodeficiency virus infection",
    "Charcot-Marie-Tooth disease and deafness",
    "Charcot-Marie-Tooth disease type 1E",
    "Charcot-Marie-Tooth disease type IE",
    "Acute disseminated encephalomyelitis following infectious disease",
    "[X]Other specified acute disseminated demyelination",
    "[X]Acute disseminated demyelination, unspecified",
    "Uhthoff's syndrome",
    "Uhthoff phenomenon"
  ],
  "total": 113
}

And can we find patients with something related to Parkinsonism? Let’s ask SNOMED CT for the terms to search for….

{
  "data": [
    "Ethopropazine poisoning",
    "Poisoning by ethopropazine",
    "Poisoning by profenamine",
    "Poisoning caused by ethopropazine",
    "Poisoning caused by profenamine",
    "Parkinsonism due to drug",
    "Parkinsonism caused by drug",
    "Antiparkinsonian drug poisoning",
    "Poisoning by anti-parkinsonism drug",
    "Poisoning caused by anti-parkinsonism drug",
    "Methylphenyltetrahydropyridine-induced parkinsonism",
    "1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism",
    "MPTP-induced parkinsonism",
    "1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonism",
    "MPTP - Methylphenyltetrahydropyridine-induced parkinsonism",
    "Postencephalitic parkinsonism",
    "SND - Striatonigral degeneration",
    "Striatonigral degeneration",
    "Striatonigral atrophy",
    "Amantadine poisoning",
    "Poisoning by amantadine",
    "Poisoning caused by amantadine",
    "Parkinsonism",
    "Disorders presenting primarily with parkinsonism",
    "Syphilitic parkinsonism",
    "Idiopathic Parkinson's disease",
    "PD - Parkinson's disease",
    "Parkinson's disease",
    "Paralysis agitans",
    "Shaking palsy",
    "Primary Parkinsonism",
    "Idiopathic Parkinsonism",
    "Parkinson disease",
    "Parkinsons disease",
    "Parkinson-dementia complex of Guam",
    "Parkinson's disease - dementia complex on Guam",
    "Parkinsonian syndrome associated with idiopathic orthostatic hypotension",
    "Parkinsonian syndrome associated with symptomatic orthostatic hypotension",
    "Neuroleptic-induced Parkinsonism",
    "Neuroleptic-induced parkinsonism",
    "Diphenhydramine poisoning",
    "Poisoning by diphenhydramine",
    "Poisoning caused by diphenhydramine",
    "Levodopa poisoning",
    "Poisoning by levodopa",
    "Poisoning by L-dopa",
    "Poisoning caused by L-dopa",
    "Poisoning caused by levodopa",
    "Poisoning by anticonvulsant AND/OR anti-Parkinsonism drug",
    "Poisoning caused by anticonvulsant AND/OR anti-Parkinsonism drug",
    "Parkinsonism with orthostatic hypotension",
    "Accidental amantadine poisoning",
    "Accidental poisoning by amantadine",
    "Accidental poisoning caused by amantadine",
    "Juvenile Parkinson disease",
    "Juvenile Parkinson's disease",
    "Secondary Parkinson's disease",
    "Secondary Parkinson disease",
    "Secondary parkinsonism",
    "Carbon monoxide-induced parkinsonism",
    "Manganese-induced parkinsonism",
    "Parkinsonism with calcification of basal ganglia",
    "Vascular parkinsonism",
    "Symptomatic parkinsonism",
    "Anticonvulsant and antiParkinsonian drug poisoning",
    "Accidental levodopa poisoning",
    "Intentional levodopa poisoning",
    "Levodopa poisoning of undetermined intent",
    "Intentional amantadine poisoning",
    "Amantadine poisoning of undetermined intent",
    "Lisuride poisoning",
    "Lysuride poisoning",
    "Accidental lisuride poisoning",
    "Accidental lysuride poisoning",
    "Intentional lisuride poisoning",
    "Intentional lysuride poisoning",
    "Lisuride poisoning of undetermined intent",
    "Lysuride poisoning of undetermined intent",
    "Bromocriptine poisoning",
    "Accidental bromocriptine poisoning",
    "Intentional bromocriptine poisoning",
    "Bromocriptine poisoning of undetermined intent",
    "Accidental ethopropazine poisoning",
    "Intentional ethopropazine poisoning",
    "Ethopropazine poisoning of undetermined intent",
    "Decarboxylase inhibitor poisoning",
    "Selegiline poisoning",
    "Accidental selegiline poisoning",
    "Intentional selegiline poisoning",
    "Selegiline poisoning of undetermined intent",
    "Accidental diphenhydramine poisoning",
    "Intentional diphenhydramine poisoning",
    "Diphenhydramine poisoning of undetermined intent",
    "Dopaminergic drug used in parkinsonism adverse reaction",
    "Adverse reaction to levodopa, L-dopa",
    "Levodopa adverse reaction",
    "Co-beneldopa adverse reaction",
    "Benserazide + levodopa adverse reaction",
    "Co-careldopa adverse reaction",
    "Carbidopa + levodopa adverse reaction",
    "Amantadine adverse reaction",
    "Apomorphine adverse reaction",
    "Lisuride adverse reaction",
    "Lysuride adverse reaction",
    "Pergolide adverse reaction",
    "Bromocriptine adverse reaction",
    "Dopaminergic drug used in parkinsonism allergy",
    "Levodopa allergy",
    "Co-beneldopa allergy",
    "Benserazide + levodopa allergy",
    "Co-careldopa allergy",
    "Carbidopa + levodopa allergy",
    "Amantadine allergy",
    "Apomorphine allergy",
    "Lisuride allergy",
    "Lysuride allergy",
    "Pergolide allergy",
    "Bromocriptine allergy",
    "Overdose of dopaminergic drug used in parkinsonism",
    "Levodopa overdose",
    "Accidental levodopa overdose",
    "Intentional levodopa overdose",
    "Levodopa overdose of undetermined intent",
    "Amantadine overdose",
    "Accidental amantadine overdose",
    "Intentional amantadine overdose",
    "Amantadine overdose of undetermined intent",
    "Lisuride overdose",
    "Lysuride overdose",
    "Accidental lysuride overdose",
    "Accidental lisuride overdose",
    "Intentional lisuride overdose",
    "Intentional lysuride overdose",
    "Lisuride overdose of undetermined intent",
    "Lysuride overdose of undetermined intent",
    "Bromocriptine overdose",
    "Accidental bromocriptine overdose",
    "Intentional bromocriptine overdose",
    "Bromocriptine overdose of undetermined intent",
    "On - off phenomenon",
    "Dystonia musculorum deformans",
    "Lubag",
    "XDP - X-linked dystonia parkinsonism",
    "X-linked torsion dystonia parkinsonism syndrome",
    "X-linked dystonia parkinsonism",
    "Torsion dystonia parkinsonism Filipino type",
    "Perry syndrome",
    "Parkinsonism with alveolar hypoventilation and mental depression",
    "Rapid onset dystonia parkinsonism",
    "DYT12 - dystonia 12",
    "Dystonia 12",
    "Familial Pick's disease",
    "Frontotemporal dementia with parkinsonism-17",
    "Wilhelmsen-Lynch disease",
    "Disinhibition-dementia-parkinsonism-amytrophy complex",
    "FTDP-17 - Frontotemporal dementia with parkinsonism 17",
    "Young onset Parkinson's disease",
    "Early onset Parkinson's disease",
    "Early onset Parkinson disease",
    "Young onset Parkinson disease",
    "Parkinsonism co-occurrent with dementia of Guadeloupe",
    "Parkinsonism with dementia of Guadeloupe",
    "Waisman syndrome",
    "Laxova Opitz syndrome",
    "Early onset parkinsonism and intellectual disability syndrome",
    "Hereditary late onset Parkinson disease",
    "Autosomal dominant late onset Parkinson disease",
    "Infantile bilateral striatal necrosis",
    "Infantile striatonigral degeneration"
  ],
  "total": 169
}