Medical questions 3 Flashcards
What are the causes of Parkinsonism?
Idiopathic Parkinson's disease Drugs (dopamine antagonists) - chlorpromazine, metoclopramide, prochlorperazine Tumours of the basal ganglia Lewy body dementia Dementia pugilistica Normal pressure hydrocephalus Parkinson Plus syndromes: multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration Post encephalitis Wilson's disease Toxins e.g. MPTP
What do you understand by the term Parkinson’s disease?
PD is a neurodegenerative disorder caused by the disruption of dopaminergic neurotransmission in the basal ganglia. Histologically, there is a loss of melanin-containing dopaminergic neurons in the substantia nigra and cytoplasmic inclusions called Lewy bodies in the surviving dopaminergic neurons. Approximately 60-80% of dopaminergic neurons are lost before the motor signs of PD emerge.
How do you distinguish dementia and dementia with Lewy bodies?
Dementia usually occurs late in PD and affects 15-30% of patients. Cognitive symptoms that occur earlier, i.e. within a year of onset of motor symptoms would suggest a diagnosis of Lewy body dementia.
What are the characteristics of multiple systems atrophy?
Characterised by varying degrees of Parkinsonism, autonomic failure, cerebellar dysfunction and pyramidal signs.
When Parkinsonian features are prominent, it is termed MSA-P. When cerebellar signs are prominent, it is termed MSA-C. When autonomic dysfunction is prominent, it is termed Shy-Drager syndrome.
What are the characteristic features of progressive supranuclear palsy?
This is the commonest Parkinson Plus syndrome. There is involvement of multiple neurotransmitter pathways.
Supranuclear gaze palsy manifests as abnormal vertical, then horizontal saccades. Other features include difficulty opening the eyes, early and prominent falls, speech and swallowing difficulties and frontal symptoms including depression, apathy and cognitive impairment.
Compared to PD, the parkinsonian features are symmetrical and axial rigidity is more prominent than limb. Tremor is less common. There is often a poor response to L-dopa. Progression is rapid, with survival from onset of 5-7 years.
What are the characteristics of corticobasal degeneration?
Characterised by frontoparietal cortical atrophy in addition to degeneration in the extrapyramidal system. Presents with atypical Parkinsonian features and associated higher cortical abnormalities including limb apraxia and cortical sensory loss. “Alien limb”. Myoclonus can also occur and dementia may develop later in the disease.
How would you distinguish the tremor in Parkinson’s from essential tremor?
Essential tremor is usually symmetrical and made worse with voluntary movement. It is often accompanied by a voice and head tremor, whereas in Parkinsonism, the tremor does not affect the head. About 50% of patients with Parkinsonism also have a postural component, but on asking the patient to write, PD patients display micrographia, whereas in ET, the script becomes larger and irregular.
How would you manage psychosis associated with anti-Parkinsonian drugs?
Clozapine is the best agent, although other agents such as quetiapine and olanzapine may be effect. Risperidone can exacerbate parkinsonism and should be avoided.
What surgical therapies are available for Parkinson’s disease?
Thalotomy
Pallidotomy
subthalamotomy
Deep brain stimulation has replaced lesion surgeries and does not involve a permanent lesion to the brain, making it reversible.
Transplantation is a potential treatment for PD.
What is motor neuron disease?
Motor neuron disease is a progressive disorder characterised by neuronal loss at all levels of the motor system from the cortex to the brainstem and anterior horn cells of the spinal cord. Physical signs therefore include both upper and lower motor neuron signs. There are different forms of motor neuron disease:
- Amyotrophic lateral sclerosis - both upper and lower motor neuron signs
- Progressive muscular atrophy - predominant lower motor neuron signs
- Primary lateral sclerosis - predominant upper motor neuron signs
- Progressive bulbar palsy - predominantly bulbar involvement (can be bulbar or pseudobulbar)
Which diseases may mimic motor neuron disease?
UMN and LMN presentation:
- Syringomyelia (often presents with LMN signs in arms and UMN signs in the legs).
- Cervical myelopathy and co-existent peripheral neuropathy (dual pathology)
- Multifocal motor neuropathy with conduction block
How would you manage a patient with MND?
MDT approach and should be guided by respect for autonomy and choice, symptom control and quality of life and palliative care.
Symptoms requiring treatment include:
Drooling - anticholinergics, TCAs, hyoscine patches
Dysphagia - consider PEG tube
Communication difficulties - SALT
Emotional liability - amitriptyline, lithium, L-DOPA
Fasciulations - magnesium, quinine, anti-epileptics
Spasticity - physiotheraphy and drugs e.g. baclofen
Limb weakness - splints, supports, physiotherapy
Respiratory symptoms - consider non-invasive support
Depression - antidepressants
Pain - analgesia
Do you know of any disease modifying treatments for MND?
Riluzole is the only licenced drug. It does not improve symptoms or prevent death, but RCTs suggest a 3 month increased survival over an 18 month trial period.
What are the common causes of cerebellar syndrome?
Demyelination (MS)
Alcoholic cerebellar degeneration
Posterior fossa space occupying lesions
Brainstem lesions
Drugs e.g. lithium, phenytoin, carbamazepine, phenobarbitone, chemotherapy
Hereditary e.g. Friedreich’s ataxia, ataxia telangiectasia
Hypothyroidism
Paraneoplastic (anti-Yo - gynaecological and breast ca, and anti-Hu antibodies - small cell carcinoma of the lung, prostate ca, sarcomas and neuroblastomas)
MSA
What is the genetic basis of myotonic dystrophy?
It is an autosomal dominant disease caused by a CTG triplet expansion in the myotonin protein kinase gene on chromosome 19, repeated up to 2000 times (normally 5036). It demonstrates expansion and anticipation.
