Dementia: Woman, 63, diagnosed with ‘rapid’ brain decline after developing myoclonus
The case study highlights the importance of remembering certain classic diagnostic elements so that dementia cases are not missed.
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Dementia is a syndrome of ongoing brain decline, beyond what can be expected as a result of old age. The condition is often recognised when signs of pronounced memory loss emerge. There are, however, other common early symptoms that can occur, like myoclonus.
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Myoclonus described sudden, brief, involuntary movements triggered by sporadic muscular contractions.
Evidence suggests seizures can accompany Alzheimer’s in earlier stages that are previously recognised, yet often escape detection.
According to the Mayo Clinic, the condition is a common side effect of several neurodegenerative disorders that can present severely or mildly.
In dementia with Lewy bodies, it tends to manifest as moderately sized jerks in about a third of cases.
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In Alzheimer's, moving in a jerky manner is common for patients in the early and later stages of the neurodegenerative disease.
At this stage, several other changes are bound to become apparent, including loss of appetite and pronounced memory deficits.
In 2017, the Journal of Alzheimer’s Disease reported that patients with Alzheimer’s disease are more prone to episodes of myoclonus and seizures.
It noted: “Patients with Alzheimer’s disease (AD) are more prone to seizures and myoclonus but the relative risk of these symptoms among other dementia types is unknown.
“Seizures in myoclonus occur with greater incidence in patients with Alzheimer’s disease than in the general population, but rates vary with diagnosis […].
“Patients often experience these symptoms early in the disease, suggesting hyper-excitability could be an important target or intervention.”
The body explains that seizures in Alzheimer’s disease patients are associated with accelerated cognitive decline.
This is caused by increased production of amyloid beta and tau in the brain, prompting the death of brain neurons.
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“Previous studies suggest that seizures and myoclonus, which are both signs of network hyper-excitability, could predict shortened survival in Alzheimer’s disease,” noted the researchers.
In 2019, Aging Medicine reported on the case of a 63-year-old woman with “rapidly progressive dementia".
The patient was eventually diagnosed with sporadic Creutzfeldt-Jakob disease - a rare disease that causes brain damage that worsens rapidly over time.
The report stated that “she had gradually become immobile and mute and had developed myoclonic jerks in bilateral upper limbs, which persisted for five to ten minutes at a time".
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Similar cases of myoclonus have been reported in patients treated with memantine, suggesting treatment for the drug may also be a risk factor.
The neuroprotective drug is prescribed to improve depression, inflammation and help prevent the onset of cognitive decline.
It can take weeks before symptoms of myoclonus resolve after the drug is discontinued.
This evidence suggests clinicians should suspect adverse drug reactions when myoclonus manifests in patients with Alzheimer's disease.
