- Seizure threshold is an individual’s balance between inhibition and excitation signals in the brain
- The lower the threshold, the more likely a person is to experience a seizure
- The risk of drug-induced seizure increases when multiple agents with potential risk are administered together 

Seizure Threshold

Drugs that have Seizure Potential 

- Symptoms associated with drug-induced seizures are similar to those of non-drug related seizures.
- Majority of seizures induced by drugs present as generalized tonic-clonic seizures
- The withdrawal of drugs such as benzodiazepines may provoke seizures
- It is important to consider whether the suspected drug has seizure potential at normal doses or at higher serum concentrations (as is the case with tricyclic antidepressants, theophylline, and clozapine)
- Many substances can lower the seizure threshold and cause seizures




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- Cerebrovascular Effect
- Cognitive Impairment and Delirium
- Neuroleptic Malignant Syndrome
- Movement Disorders
- Seizure Disorders
- Serotonin Syndrome
- Insomnia

Examples of Drug-Induced Neurologic Conditions

Lane RJ, Routledge PA. Drug-induced neurological disorders. Drugs. 1983;26(2):124-147. doi:10.2165/00003495-198326020-00002



Drug-Induced Neurologic Conditions

Also known as cerebellar syndrome
It is a consequence of disrupting the normal function of the brain that is responsible for coordination and balance. Many cases are reversible but the permanent cerebellar syndrome can occur.

Cerebrovascular Effect

A drug-induced neurologic disorder caused by neuroleptic and antipsychotic drugs. Thought to result from dopamine receptor D2 blockade in the corpus striatum, spinal cord, and hypothalamus. Once begun, symptoms progress rapidly and reach peak severity at 72 hours. 

Neuroleptic Malignant Syndrome

Delirium can be a side effect of drugs, especially in elderly patients. It is acute in onset and results in fluctuations in cognition, mood, attention, and arousal. Delirium can also be reversed when the underlying causative agent is removed. Prescribers can refer to the Beers Criteria to determine which drugs are linked to cognitive impairment.

Delirium and Cognitive Impairment 

Serotonin Syndrome (SS) include predictable symptoms resulting from excess serotonin  and overstimulation of 5-HT receptors. SS can range from mild to severe and is potentially fatal, although its incidence is low.  SS rarely occurs with use of a single agent; it is more commonly the result of a drug-drug interaction. 

Serotonin Syndrome

Seizure Disorders

Drug-induced movement disorders (DIMDs) can reduce the quality of life, decrease drug adherence, and cause compromised performance of motor skills. 
Parkinsonism, akathisia, tardive syndrome, and acute dystonia are associated with DIMDs. 

Movement Disorders

Insomnia is a common health concern that causes significant distress and disruption in daily life, due to difficulty with and lack of sleep. Insomnia tends to be associated with an increased risk of developing physical health problems, anxiety, and depression.

Insomnia 

A sleep disorder that consists of not getting enough sleep.

Insomnia

Insomnia, the most prevalent sleep disorder, is characterized by a persistent difficulty in initiating or maintaining sleep. Individuals with this condition often experience significant delays before falling asleep and may wake up frequently during the night, struggling to resume sleep. According to diagnostic criteria, these sleep disturbances must occur at least three nights a week for a minimum of one month.

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