From the Guidelines
Brisk reflexes are a clinically significant finding that may indicate an upper motor neuron lesion, prompting further neurological examination and potentially warranting prompt neurological consultation. When assessing reflexes, clinicians grade them on a scale from 0 (absent) to 4+ (hyperactive with clonus), with brisk reflexes typically falling in the 3+ to 4+ range. The presence of brisk reflexes should prompt further neurological examination, including checking for other upper motor neuron signs like Babinski sign, clonus, and muscle tone abnormalities, as seen in conditions such as spasticity, which is defined as velocity-dependent hyperactivity of tonic stretch reflexes 1.
Some key points to consider when evaluating brisk reflexes include:
- The pattern and distribution of hyperreflexia can help localize the lesion—bilateral findings suggest a central process while unilateral findings may indicate a focal lesion.
- Clinical context and accompanying symptoms are essential for proper interpretation, as some individuals naturally have somewhat brisk reflexes without pathology.
- Brisk reflexes may be associated with significant pain and functional disturbances, particularly in conditions like spasticity, which can result in contractures and render the affected limb functionless 1.
- Management of brisk reflexes and associated conditions like spasticity may involve a stepwise approach, including positioning, passive stretching, and range of motion exercise, as well as oral medications like tizanidine, baclofen, and dantrolene, although the evidence for these treatments is limited and their effectiveness may vary depending on the individual and the underlying condition 1.
Overall, the clinical significance of brisk reflexes lies in their potential to indicate underlying neurological conditions and prompt further evaluation and management to prevent or mitigate associated morbidity and mortality.
From the Research
Clinical Significance of Brisk Reflexes
Brisk reflexes can be an indicator of various neurological conditions. The following points highlight the significance of brisk reflexes in different clinical contexts:
- Brisk deep-tendon reflexes have been identified as a distinctive phenotype in an Argentinean spinocerebellar ataxia type 2 pedigree, suggesting that modifier genes could influence the clinical phenotype of this condition 2.
- In a case of rheumatoid meningitis, brisk reflexes were observed in a patient presenting with severe encephalopathy, bilateral Babinski sign, and lymphocytic pleocytosis, highlighting the importance of considering CNS involvement in patients with rheumatoid arthritis 3.
- The assessment of excitability in brainstem circuits, including the blink reflex and startle reaction, can provide valuable information on the functioning of these circuits in various neurological disorders 4.
- Brisk reflexes can be an important diagnostic tool in assessing neurological disturbances, and motion analysis can be used to objectively assess the patellar tendon reflex in conditions such as cerebral palsy 5.
- A study on clinical techniques for use in neurological physical examinations recommends a systematic and flexible approach to exploring motor and reflex functions, including the examination of myotatic reflexes, cutaneomucous reflexes, and spinal cord or defence automatism reflexes 6.
Key Findings
- Brisk reflexes can be associated with spinocerebellar ataxia type 2, rheumatoid meningitis, and cerebral palsy.
- Motion analysis can be used to objectively assess the patellar tendon reflex and confirm a 'brisk' response in certain populations.
- The assessment of excitability in brainstem circuits can provide valuable information on the functioning of these circuits in various neurological disorders.
- A systematic and flexible approach to exploring motor and reflex functions is recommended in neurological physical examinations.