Differential Diagnosis for New Tremor in an 87-year-old Patient
Single most likely diagnosis
- Lithium-induced tremor: This is the most likely cause given the patient's medication regimen. Lithium is well-known to cause tremors, especially in elderly patients or at higher doses. The tremor can be a side effect of lithium therapy, and given the patient's age and the fact that they are on lithium, this becomes a highly probable cause.
Other Likely diagnoses
- Venlafaxine-induced tremor: Venlafaxine, an antidepressant, can also cause tremors as a side effect. Although less common than with lithium, it's still a plausible cause, especially considering the patient's polypharmacy.
- Hydromorphone withdrawal or fluctuation: While hydromorphone itself is less likely to cause tremors directly, withdrawal or significant fluctuations in its levels could potentially lead to tremors. This is more speculative but should be considered given the patient's use of this opioid for pain management.
- Dementia-related tremor: Certain types of dementia can present with or progress to include movement disorders such as tremors. Given the patient's diagnosis of dementia, this could be a contributing factor, although it might be harder to distinguish from medication side effects.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Hyperthyroidism: Although less common, hyperthyroidism can cause tremors and is a condition that would have significant implications if missed. Elderly patients might not exhibit the typical symptoms of hyperthyroidism, making it a "do not miss" diagnosis.
- Vitamin B12 deficiency: A deficiency in vitamin B12 can lead to neurological symptoms, including tremors. Given the potential for serious neurological damage if left untreated, this is an important diagnosis not to miss.
- Medication overdose or toxicity: Overdose or toxicity from any of the patient's medications could potentially cause tremors. Given the patient's regimen, lithium toxicity is a particular concern due to its narrow therapeutic index.
Rare diagnoses
- Wilson's disease: Although extremely rare, especially as a new diagnosis in an elderly patient, Wilson's disease can cause tremors among other neurological symptoms. It's worth considering in patients with unexplained tremors and other signs of neurological deterioration, but it's much less likely given the patient's age and presentation.
- Other movement disorders: Rare movement disorders such as essential tremor, if not previously diagnosed, or other less common conditions like dystonic tremor, could be considered. However, these would be less likely given the patient's current medication regimen and medical history.