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Is It Essential Tremor or a Parkinsonian Syndrome?

Is It Essential Tremor or a Parkinsonian Syndrome?. Diagnostic Considerations in Primary Care. Faculty Tanya Simuni, MD Director, Parkinson's Disease and Movement Disorders Center Northwestern University Chicago, Illinois. Learning Objectives.

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Is It Essential Tremor or a Parkinsonian Syndrome?

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  1. Is It Essential Tremor or a Parkinsonian Syndrome? Diagnostic Considerations in Primary Care Faculty Tanya Simuni, MD Director, Parkinson's Disease and Movement Disorders Center Northwestern University Chicago, Illinois

  2. Learning Objectives • Outline challenges to accurate and timely diagnosis of Parkinson disease (PD) in the primary care setting • Compare clinical signs and symptoms of PD and other parkinsonian syndromes with those of essential tremor • Recognize when neuroimaging is appropriate in the diagnostic workup of patients with suspected parkinsonian syndromes

  3. Epidemiology of PD in the United States • 1 million patients have PD • Annual incidence:15-20 per 100,000 • 50,000-60,000 new cases per year • Prevalence increases with age (per 100,000) • 40-49 years: 23 • 70-79 years: 525 • 80-89 years: 1145 • More common in whites vs blacks or Asians • More common in Midwest and Northeast vs other regions; more common in urban vs rural counties Watts RL, et al[1]; Willis AW, et al. [2]

  4. UK PDSBB Clinical Diagnostic Criteria Step 1: Diagnosis • Bradykinesia • At least 1 • Muscular rigidity • 4-6 Hz rest tremor • Postural instability • Not visual • Not vestibular • Not cerebellar • Not sensory Hughes AJ, et al.[3]

  5. UK PDSBB Clinical Diagnostic Criteria Step 2: Exclusion Criteria • History of repeated strokes, repeated head injury, or definite encephalitis • Oculogyric crises • Neuroleptic treatment at onset of symptoms • Sustained remission • Strictly unilateral after 3 years • Supranuclear gaze palsy • Cerebellar signs; early autonomic involvement • Early, severe dementia; Babinski sign • Cerebral tumor or hydrocephalus on CT • MPTP exposure • Poor response to levodopa Hughes AJ, et al.[3]

  6. UK PDSBB Clinical Diagnostic Criteria Step 3: Supportive Positive Criteria • 3 or more required for definite diagnosis • Unilateral onset • Rest tremor • Progressive disorder • Persistent asymmetry, worse on onset side • 70%-100% response to levodopa • Severe levodopa-induced dyskinesias • Levodopa response ≥ 5 years • Disease course ≥ 10 years Hughes AJ, et al.[3]

  7. UK PDSBB Clinical Diagnostic Criteria Diagnostic Accuracy Initial studya: 100 cases with PD diagnosed prospectively 76% accuracy on autopsy Criteria applied retrospectively improved accuracy to 82% Follow-up studyb: Criteria applied prospectively in 100 cases 90% accuracy on autopsy a. Hughes AJ, et al[3]; b. Hughes AJ, et al.[4]

  8. Diagnostic Accuracy Improves With Disease Duration: Imaging Studies • Proportion of SWEDDs decreases with length of time since diagnosis • Clinical trials: • ELLDOPA: 14% SWEDDs at 6 months • REAL-PET: 12% SWEDDs at 9 months • CALM-PD: 4% SWEDDs at 18 months • NIL-A-CIT: 2% SWEDDs at 22 months SWEDD=scan without evidence of dopaminergic deficit; indicates misdiagnosis of parkinsonism. Seibyl J, et al.[5]

  9. Other Neurodegenerative Disorders With Presynaptic Dopamine Deficiency • More common • Progressive supranuclear palsy • Multiple system atrophy • Corticobasal ganglionic degeneration • Diffuse Lewy body disease • Less common • ALS-Parkinsonism-Dementia/of Guam • Alzheimer with extrapyramidal signs • Rigid variant of Huntington disease

  10. Parkinsonian Syndromes • Parkinsonian syndromes refer to neurologic disorders associated with a loss of dopamine neurons • PD (~85% of cases of parkinsonism)a • MSA (< 5%)a • PSP (< 5%)a • Does not include cases of clinical parkinsonism where there is not an associated loss of dopamine neurons • Drug-induced parkinsonism (7%-35% of all cases of parkinsonism)a,b,c • Vascular parkinsonism (~4%-12%)d • Psychogenic parkinsonism (0.17%-0.5%)b a. Rajput AH, et al[6]; b. Kägi G, et al[7]; c. Thanvi B, Treadwell S[8]; d. Thanvi B, et al.[9]

  11. What Is ET? • ET is a specific neurologic disorder • Also known as “familial tremor” • Tremor involves hands, head, voice, sometimes legs and trunk • Essential means • There is no other cause for tremor • There are no other neurologic signs • Familial means it can be hereditary

  12. Other Causes of Tremor • Medication induced • Electrolyte imbalance • Thyroid dysfunction • PD • Posttraumatic tremor • MS-related tremor • Other neurologic conditions

  13. Manifestations of ET • Symmetric tremor • Tremor is the single manifestation (can include hand, vocal, head, trunk, leg tremors) • Postural, kinetic (associated with action) tremor

  14. How Common Is ET? • ET is the most common movement disorder • About 5% of people age > 65 y have ET • ET frequently is not diagnosed • ET usually starts age ≥ 40 y but can be seen in childhood • ET symptoms start insidiously and progress slowly • ET is not dangerous but can be disabling Louis ED.[10]

  15. Is ET Related to PD? • NO, NO, NO • ET tremor differs from PD • ET patients do not feel slow or stiff • ET patients do not have difficulty walking • ET does not progress into PD • Some patients can have both diagnoses

  16. Areas of Uncertainty a. Lees AJ, et al[11]; b. Hauser RA, et al[12]; c. Pahwa R, et al[13]; d. Hauser RA, et al[14]; e. Solida A, et al[15]; f. Marshall V, et al[16]; g. Bhidayasiri R.[17]

  17. Misdiagnosis of ET and PD Is Common • Clinical studies have found a high level of misdiagnosis of ET and PD • A previous diagnosis of PD was rejected in 15% of patients using standardized criteria and > 1 year follow-upa • ~26% of patients receiving antiparkinsonian medication did not have a parkinsoniansyndromeb • A previous diagnosis of ET was rejected in 37% of patients using standardized criteriac a. Schrag A, et al[18]; b. Meara J, et al[19]; c. Jain S, et al.[20]

  18. Case Presentation • Woman age 60 y presents for evaluation of a long-standing tremor • 7-year history of bilateral symmetric hand tremor that occurs with activity and is especially bothersome when she writes or holds a cup • Tremor improves with wine. Her father had a similar tremor • Not bothersome but has increased in past several months • Recently noticed occasional right-arm tremor at rest

  19. Case Presentation (cont) • Neurologic examination • Bilateral action tremor when she holds a cup • Slight rest tremor component in the right arm • Trace of increased tone in the right wrist • Normal balance and gait • No other medical history

  20. SPECT and PET Ligands • The most commonly used SPECT ligands bind to the striatal presynaptic membrane-associated dopamine active transporter protein • Reduction of the dopamine transporter correlates with the loss of presynaptic dopamine • Other ligands measure • Vesicular monoamine transport • DOPA decarboxylase activity

  21. Dopamine System Imaging Amino Acid Transporter Presynaptic radioligands DOPA decarboxylase (measures dopamine synthesis) VMAT-2 Vesicle DAT (provides measure of functioning dopaminergic terminals) DAT Dopamine VMAT-2 (marker for dopaminergic terminals) D2 Receptor Postsynaptic radioligands D2 receptor Mitochondrion Cummings JL, et al.[21] Adapted with permission.

  22. Who Benefits From Diagnostic Imaging? • Patients with a classic presentation of PD or ET do not require additional diagnostic imaging • Dopamine transporter SPECT cannot differentiate different forms of parkinsonism (eg, PD, MSA, PSP) • Features that raise concerns about an alternative cause of parkinsonism that could prompt diagnostic imaging • Patients with atypical features that are beyond the scope of a classic PD presentation • Patients with poor response to an appropriate trial of dopaminergic therapy

  23. Dopaminergic Imaging vs Normal Cummings JL, et al.[21] Republished with permission.

  24. Case Conclusion • The patient had a history of long-standing ET supported by a positive family history (present in 50% of patients) and response to alcohol • In addition to the bilateral action tremor typical of ET, the examination demonstrates subtle features of asymmetric rest tremor, suggestive of early PD • The clinical diagnosis is ET but you are concerned that she may have early PD in addition • Two possible approaches • Clinical follow-up to see if she develops clearer features of parkinsonism • Obtain a dopamine transporter SPECT scan • Patient elects to have the SPECT scan • SPECT demonstrates normal dopamine uptake • ET is confirmed

  25. SPECT Images: Normal vs PD Early PD • Normal

  26. Summary • PD and ET are clinical diagnoses, but symptoms can sometimes overlap, causing misdiagnosis • Timely and accurate diagnosis of PD and ET will advance appropriate treatment and improve the patient’s quality of life • Patients with atypical symptoms may benefit from dopamine transporter SPECT to differentiate between a parkinsonian syndrome and ET

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