Effects on the Nervous System

The nervous system regulates and maintains body function through stimuli reception and response. Some cytotoxic drugs can cause changes in the central nervous system and/or the peripheral nervous system. The brain and spinal cord comprise the central nervous system. The peripheral nervous system includes the motor and sensory nerves leading to and from the spinal cord, the cranial nerves, and the nerves of the autonomic nervous system. The cranial nerves, part of the peripheral nervous system, are connected directly to the brain and are important for movement and touch sensations of the head, face, and neck. Cranial nerves are also important for special senses of vision, hearing, taste, and smell.

Central nervous system toxicity can produce symptoms such as confusion, dizziness, and an unsteady gait. Toxicity to the peripheral nervous system, which comprises the sensory and motor nerves, causes abnormal sensations known as paresthesias, including numbness and tingling of the hands and feet. Toxicity affecting the autonomic nervous system causes constipation, paralytic ileus, urinary retention, and bladder and bowel incontinence.

Risk factors that increase the possibility of neurotoxicity include intrathecal administration of drugs, radiation to the head area, impaired renal function, concomitant use of aminoglycosides, cumulative doses of vinca alkaloids such as vincristine and vinblastine, increasing age, and previous neurotoxic sensitivity.

Management strategies for neurotoxicity include:

a. Advising the patient to take a prophylactic stool softener and high-fiber foods to prevent constipation.
b. Providing bladder and bowel training for incontinence or urinary retention.
c. Assessing visual acuity, pupillary reaction to light, and visual fields.
d. Assessing the patient’s level of consciousness.
e. Instituting seizure precautions if indicated.
f. Instructing the patient’s family or significant other to supervise patient activity and institute safety precautions if needed.

Side effects of vinca alkyloid drugs such as vincristine and vinblastine can cause urinary retention and constipation.

Check with Cancersymptoms.org for information about pharmacologial interventions for cognitive dysfunction secondary to chemotherapyy.

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