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Clonus is a rhythmic oscillating stretch reflex that is related to upper motor neuron lesions. Therefore, clonus is generally accompanied by hyperreflexia. Testing for clonus is performed as part of the neurological exam. This activity describes how to elicit clonus and its clinical relevance and highlights the role of the interprofessional team in the management of patients with clonus. Objectives: List the causes of clonus. Explain how to elicit clonus on a physical exam. Explain the clinical relevance of clonus. Explain the importance of optimizing care coordination amongst the interprofessional team to enhance the delivery of care for patients with clonus. Access free multiple choice questions on this topic.

Clonus is a rhythmic, oscillating, stretch reflex, the cause of which is not totally known; however, it relates to lesions in upper motor neurons and therefore is generally accompanied by hyperreflexia.  Therefore, clonus is used as part of the neurological physical exam to evaluate the status of a patient’s nervous system.  It can be evaluated in many joints but is most commonly seen in the ankle joint by briskly dorsiflexing the foot. An illustrative example of what clonus might look like is a clinician tapping the patellar tendon once lightly and a subsequent series of obvious repeated knee extensions and relaxations going on for a dozen beats. The test is free of cost, generally requires no equipment and can be performed rapidly and easily in a hospitalized patient.  Like other signs of upper motor neuron syndrome clonus indicates some insult to the central rather than peripheral nervous system, so part of its utility as a clinical examination skill is in differentiating the two. It has other roles, for instance, it is prognostic of seizures in certain drug overdoses and therefore can be used to decide when to treat this condition prophylactically.

Part of what makes clonus a useful assessment is how quickly and easily it can be performed without specialized equipment or added cost. The test can be performed by nurses, medical students, the primary caregiver, or the specialist. It is commonly used to evaluate patients for which there is a concern for upper motor neuron syndrome, for instance, in patients at risk of stroke. Many types of clinicians are trained to perform clonus including nurses and physicians. The clearest way to document clonus findings is to explain what was found and how it was performed, but often, simply noting that reflexes are "4" or "5" is adequate. If clonus is discovered on the physical exam, the nurse practitioner or primary care provider should refer the patient to a neurologist for further investigation. In addition, a pharmacist should be consulted to evaluate drugs as an underlying cause. Once the etiology is determined, and a course of action undertaken, the interprofessional team will communicate to monitor for a successful outcome. [Level V]