Status Epilepticus and Anticonvulsants

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Questions and Answers

A patient with advanced Parkinson's disease, previously well-managed on carbidopa-levodopa, now requires escalating dosages to achieve therapeutic efficacy. Which of the following mechanisms MOST accurately describes the underlying cause for this phenomenon?

Adaptive desensitization of dopamine autoreceptors on presynaptic dopaminergic neurons, diminishing inhibitory feedback and increasing dopamine turnover.
Progressive downregulation of postsynaptic dopamine D2 receptors in the striatum, leading to diminished sensitivity to levodopa. (correct)
Increased expression of COMT (catechol-O-methyltransferase) in peripheral tissues, leading to elevated pre-systemic levodopa degradation.
Pharmacokinetic alterations resulting in accelerated hepatic metabolism of levodopa due to enzyme induction by chronic administration.

A geriatric patient with a history of Parkinson's disease and well-controlled narrow-angle glaucoma presents with new-onset motor fluctuations and dyskinesias despite optimized carbidopa-levodopa therapy. What is the MOST appropriate pharmacological intervention, considering the patient's glaucoma?

Prescribe amantadine, carefully titrating the dose, to manage dyskinesias, and consult with ophthalmology for potential adjustments to glaucoma management. (correct)
Initiate a low dose of a dopamine receptor agonist (e.g., ropinirole) with concurrent administration of pilocarpine eye drops to counteract potential mydriatic effects.
Discontinue carbidopa-levodopa and initiate anticholinergic therapy (e.g., trihexyphenidyl) to mitigate motor symptoms, while closely monitoring cognitive function.
Administer a selective MAO-B inhibitor (e.g., selegiline) to augment dopaminergic neurotransmission while closely monitoring intraocular pressure.

A patient on chronic carbidopa-levodopa therapy reports persistent nausea and anorexia, significantly impacting their nutritional status. Which of the following strategies represents the MOST evidence-based approach to mitigate these adverse gastrointestinal effects?

Administer ondansetron, a selective 5-HT3 receptor antagonist, to block serotonin-mediated emetic pathways in the chemoreceptor trigger zone.
Recommend dividing the daily carbidopa-levodopa dose into smaller, more frequent administrations, taken with low-protein meals to minimize competition for intestinal absorption. (correct)
Prescribe metoclopramide, a dopamine receptor antagonist and prokinetic agent, to enhance gastric emptying and reduce nausea.
Initiate a proton pump inhibitor (PPI), such as omeprazole, to reduce gastric acid secretion and alleviate potential levodopa-induced gastritis.

A patient with Parkinson's disease develops severe choreiform movements involving the face, trunk, and limbs after several years of carbidopa-levodopa treatment. Which neurobiological mechanism is MOST directly implicated in the pathophysiology of these dyskinesias?

Excessive stimulation of D1 receptors in the direct pathway of the basal ganglia, leading to disinhibition of thalamocortical projections. (A) Signup and view all the answers

A patient currently managed with carbidopa-levodopa and selegiline for Parkinson's disease is diagnosed with a major depressive episode. Which of the following antidepressant strategies is MOST contraindicated, considering the potential for adverse drug interactions?

Administering a monoamine oxidase inhibitor (MAOI) such as phenelzine, to enhance monoaminergic neurotransmission. (C) Signup and view all the answers

A 68-year-old male with idiopathic Parkinson's disease presents to the emergency department with a sudden onset of severe headache, neck stiffness, and elevated blood pressure (220/120 mmHg). He takes carbidopa-levodopa and over-the-counter pseudoephedrine for nasal congestion. Which of the following is the MOST likely cause?

Hypertensive crisis precipitated by the interaction between pseudoephedrine (a sympathomimetic amine) and levodopa, leading to excessive catecholamine release. (B) Signup and view all the answers

A patient with Parkinson's disease who is stable on carbidopa-levodopa develops restless leg syndrome (RLS) at night, significantly disrupting their sleep. Which medication would be the MOST appropriate FIRST-LINE treatment?

Pramipexole, a non-ergot dopamine receptor agonist, to directly stimulate dopamine receptors in the brain. (A) Signup and view all the answers

A patient receiving carbidopa-levodopa therapy for Parkinson's disease reports an unusual side effect: compulsive gambling. After discontinuing carbidopa/levodopa, which of the following would be MOST appropriate?

Refer the patient for cognitive behavioral therapy (CBT) targeting impulse control and maladaptive behaviors, along with psychiatric evaluation. (A) Signup and view all the answers

A patient with Parkinson's disease is being treated with selegiline and carbidopa-levodopa, has developed tolerance and requires careful monitoring. Which finding is MOST indicative of evolving levodopa-induced dyskinesias that warrants immediate clinical attention and potential therapeutic adjustment?

The presence of rapid, jerky, and purposeless movements (chorea) involving the face, trunk, and limbs, with peak severity coinciding with peak levodopa plasma concentrations but with minimal functional impact. (D) Signup and view all the answers

When counseling a 70-year-old patient with Parkinson's disease who is initiating carbidopa-levodopa therapy, what is the MOST critical instruction to provide regarding meal timing and dietary considerations to optimize drug efficacy and minimize adverse effects?

Recommend that the patient consume a low-protein diet, particularly during daytime hours, and shift protein intake to the evening meal to minimize fluctuations in motor performance. (C) Signup and view all the answers

In a patient experiencing status epilepticus refractory to first-line benzodiazepines, which of the following considerations is MOST critical when initiating phenytoin intravenously, given its pharmacokinetic profile and potential adverse effects?

Administering a slow IV push at a rate not exceeding 50 mg/min, followed by continuous cardiac monitoring and frequent blood pressure checks due to the risk of hypotension and arrhythmias, particularly in elderly patients with pre-existing cardiovascular conditions. (B) Signup and view all the answers

A patient on long-term phenytoin therapy presents with insidious onset of behavioral changes, progressive cognitive decline, and mild cerebellar ataxia despite therapeutic serum phenytoin levels (12 mcg/mL). Which of the following diagnostic modalities is MOST appropriate to evaluate for potential chronic phenytoin toxicity?

Magnetic resonance imaging (MRI) of the brain with and without contrast to evaluate for cerebellar atrophy or other structural abnormalities. (A) Signup and view all the answers

A patient with a known seizure disorder and well-controlled on phenytoin presents to the emergency department with new-onset atrial fibrillation with rapid ventricular response. Which of the following antiarrhythmic agents should be avoided due to potential pharmacokinetic interactions with phenytoin?

Amiodarone, due to its potential to inhibit the metabolism of phenytoin, leading to increased serum phenytoin levels and toxicity. (B) Signup and view all the answers

A patient stabilized on long-term phenytoin develops acute renal failure secondary to aminoglycoside-induced nephrotoxicity. How should the management of their phenytoin dosage be modified, considering the altered renal function and potential impact on phenytoin protein binding?

Decrease the phenytoin dose by 25-50% and monitor serum levels closely due to potential displacement of phenytoin from protein binding sites and reduced clearance of unbound drug. (D) Signup and view all the answers

A patient with Parkinson's disease experiences persistent 'off' periods despite optimized levodopa/carbidopa therapy and adjunctive use of a COMT inhibitor. Which of the following strategies is MOST appropriate to address these motor fluctuations, considering the complex interplay of dopaminergic and non-dopaminergic pathways?

Consider deep brain stimulation (DBS) of the subthalamic nucleus (STN) or globus pallidus interna (GPi) to provide continuous modulation of basal ganglia circuitry. (D) Signup and view all the answers

A patient with advanced Parkinson's disease develops severe, debilitating dyskinesias despite multiple adjustments to their levodopa regimen. Which of the following interventions is MOST likely to provide sustained relief from these levodopa-induced motor complications, considering the potential for long-term adverse effects?

Referring the patient for Duopa (carbidopa/levodopa enteral suspension) therapy via percutaneous endoscopic gastrostomy (PEG) tube to provide continuous dopaminergic stimulation. (B) Signup and view all the answers

A patient taking phenytoin for seizure control reports experiencing significant gingival hyperplasia. Beyond meticulous oral hygiene, which intervention demonstrates the MOST evidence-based approach to managing this adverse effect?

Switching to an alternative anticonvulsant, such as lamotrigine or levetiracetam, associated with a lower risk of gingival hyperplasia. (A) Signup and view all the answers

A patient with Parkinson's disease experiences disabling "freezing" episodes, particularly when initiating movement or navigating narrow spaces. Which of the following non-pharmacological interventions has demonstrated the MOST efficacy in mitigating these episodes?

Utilizing sensory cues, such as visual targets or auditory signals, to bypass impaired basal ganglia circuitry and facilitate motor initiation. (C) Signup and view all the answers

A patient with Parkinson's disease on long-term levodopa/carbidopa therapy develops peak-dose dyskinesias accompanied by unpredictable "on-off" fluctuations. What is the MOST appropriate strategy to mitigate these motor complications, considering the potential for long-term adverse effects associated with each intervention?

Refer the patient for deep brain stimulation (DBS) of the subthalamic nucleus to modulate neuronal activity and reduce motor complications. (C) Signup and view all the answers

A patient with a seizure disorder well-controlled on phenytoin presents with signs and symptoms suggestive of phenytoin toxicity, but their measured serum phenytoin level is within the therapeutic range (10-20 mcg/mL). Which of the following factors could MOST plausibly explain this apparent discrepancy?

The patient is concurrently taking a medication that inhibits the hepatic metabolism of phenytoin, increasing the concentration of unbound (free) phenytoin. (C) Signup and view all the answers

Flashcards

Extrapyramidal Side Effects

Movement disorders that can occur with antipsychotic medication use.

Restless Leg Syndrome

A condition characterized by an uncontrollable urge to move the legs, often treated with antiparkinsonian medications.