Different Types of Drug-Induced Neurological Disorders

What Are Drug-Induced Neurological Disorders?

Identification of drug-induced neurological disorders is significant, as when detected early, irreversible damage can be avoided. This review summarizes the more significant drug-induced neurological disorders and focuses on the recognized neurological side effects. Some of the drugs mentioned here may also worsen neurological conditions, many of which are subclinical and go undiagnosed.

What are the Different Types of Drug-Induced Neurological Disorders?

• Cerebrovascular Effects:

  • The cerebellar syndrome occurs when there is an interruption in the normal functioning of the brain, as a result of which balance and coordination are impaired. It is one of the rare occurrences. Numerous medications, including Phenytoin, Lithium, Carbamazepine, some chemotherapy drugs, and Aminoglycoside antibiotics, have been associated with drug-induced cerebellar syndrome. Some patients may also experience dysarthria (difficulty in speaking as a result of weakness in the muscles responsible for speech) and nystagmus (repetitive, uncontrolled, and involuntary eye movement), in addition to a loss of coordination. Most of the drug-induced cerebellar syndrome is reversible. However, permanent damage can occur due to high dosages of the drugs and repeated use of drugs like antipsychotics and lithium.

  • Hormone therapy for the use of Estrogen and Progestin has shown a significant increase in cases of deep vein thrombosis, pulmonary embolism, heart attack, and stroke. Menopausal women are no longer prescribed hormone replacement therapy, but women taking oral contraceptives or injectable hormone therapies must be aware of the possibility of neurologic side effects.

  • The healthcare worker must assist the patient in managing any modifiable risk factors, such as hypertension, diabetes, and hypercholesterolemia when drugs with potential cerebrovascular effects are clinically prescribed. Other non-pharmacological interventions include dietary modifications, increased physical activity, and quitting smoking.

  • As per reports, antipsychotic medications have been linked to cerebrovascular and other vascular effects. Patients with dementia-related psychosis over the age of 73 have shown a significantly higher incidence of transient ischemic attack, cerebral ischemia, unspecified cerebrovascular disorders, and stroke when compared to placebo.

• Cognitive Impairment and Delirium:

  • Delirium is a neurologic adverse drug reaction that can occur, particularly in elderly patients.

  • More people need to be aware of the medications that cause cognitive impairment, especially older patients.

  • Delirium is usually abrupt in onset and causes changes in cognition, emotions, attention, and arousal. When the underlying cause of the delirium is found and eliminated, it can be treated. Adverse effects may result in subtle executive function impairment, which would reduce the brain's capacity to control cognitive functions like working memory, problem-solving abilities, and verbal reasoning.

  • Anticholinergic drugs possess a serious and highest risk of causing confusion in patients. It also leads causes cognitive decline.

• Neuroleptic Malignant Syndrome (NMS):

  • Another drug-induced neurologic disorder is neuroleptic malignant syndrome (NMS). Neuroleptic and antipsychotic medications are the primarily responsible drugs. It is characterized by skeletal rigidity, autonomic instability, fever, and cognitive changes, which are caused by dopamine receptor D2 blockade in the corpus striatum (part of the brain), spinal cord, and hypothalamus.

  • Both the use of neuroleptic and antipsychotic drugs causes NMS; however, the risk is higher when they are given together. First-generation antipsychotic drugs like Chlorpromazine and Haloperidol, as well as medications with Dopamine-antagonist activity like Metoclopramide, can all result in NMS. Levodopa and other Dopamine agonists should not be stopped suddenly as this may increase the risk of NMS.

  • Although the onset of NMS is unpredictable, practicing methods such as the concurrent use of multiple risk-bearing medications, rapid dosage changes, and the use of conventional antipsychotic drugs with known side effects, all contribute to an overall increased risk of the disorder.

• Movement Disorders:

  • Drugs used to treat psychiatric conditions, medications for Parkinson's disease, and medicines for gastrointestinal disorders, all increase the risk of developing adverse neurologic effects. Patients taking a variety of these drugs continue to face challenges as a result of drug-induced movement disorders (DIMDs).

  • Due to impaired performance of the motor skills required for daily living, DIMDs can lower the standard of life, decrease drug compliance, and increase the risk of negative outcomes.

• Seizure Disorders:

  • It is challenging to distinguish between drug-induced seizures and newly-onset seizure disorders linked to medical conditions. It is believed that abnormal brain nerve cell signaling causes seizures. Movements, actions, level of awareness, and consciousness may all be affected by these abnormal electrical firings.

  • The signs and symptoms of drug-induced seizures are comparable to those of seizures that are not drug related. Most drug-induced seizures manifest as generalized tonic-clonic seizures. Many drugs have the potential to decrease the seizure threshold. A person with a lower seizure threshold is more likely to experience a seizure. When several drugs with potential risks are administered simultaneously, the risk of drug-induced seizures increases.

  • Tricyclic antidepressants, Theophylline, and Clozapine are a few of the drugs that can cause drug-induced seizures. It is crucial to consider whether a suspected drug has been linked to seizures at low doses or mostly at higher serum concentrations when looking into a potential drug-induced seizure.

  • Drug use and history should be examined in patients with newly developed seizures in order to rule out the possibility of drug-induced seizures. Drug-induced seizures are rare; however, they can happen at higher doses, in risk populations, and when combined with other medications that cause seizures.

• Insomnia:

  • Insomnia is a sleep disorder that is commonly seen in females and the elderly population.

  • Patients who struggle with insomnia might claim they have trouble going to sleep, staying asleep, or staying asleep. No matter which stage of sleep is affected, all patients with insomnia report having trouble sleeping.

  • Although it is well known that stimulants (these drugs increase the activities of the central nervous system) can cause insomnia, other medications, such as antidepressants, corticosteroids, beta-agonists, and antiparkinsonian agents, should also be considered by the doctor while planning for insomnia treatment.

  • Insomnia hampers the quality of life of the patient by reducing their ability to perform and manage cognitive activities. It also puts the patient at risk of developing comorbid medical and psychiatric conditions and increases their chances of accidental injury.

  • The healthcare worker should identify the drug that causes insomnia in the patient, and it should be stopped immediately.

  • In case discontinuation of the medicine is not allowed in a patient, lowering the dosage, giving the dose early in the day, instructing the patient about sleep hygiene practices, and other non-pharmacological interventions should be used.

• Serotonin Syndrome:

  • Serotonins syndrome (SS) is characterized by a set of identifiable symptoms caused by an excess of serotonin and an overstimulation of 5-HT receptors. Neuromuscular excitability, behavioral and cognitive changes, and autonomic instability are seen in such patients. Patients typically exhibit agitation, tremor, sweating, fever, nausea, and vomiting.

  • The similarities observed in patients with neuroleptic malignant syndrome may be explained by the inverse neurotransmitter relationship between excess serotonin and reduced dopamine secretion. Although its overall incidence is low, SS can range from mild to severe and can be fatal.

  • Drugs that cause SS include antidepressants like serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors. Other drugs like pethidine and drugs used for migraines like Triptans can also cause serotonin syndrome.

Conclusion

Movement disorders can be brought on by a variety of drugs. Antipsychotics and antiemetics are more commonly involved. The neurological disorder may have an acute, subacute, or chronic onset. The severity can be mild to severe and even fatal. To enable quick intervention, it is crucial to identify drug-induced neurological disorders as soon as possible. This involves discontinuing the offending medication, providing supportive care, and at times using other pharmacological remedies.