CLINICAL EXAMINATION IN EVALUATION OF NEUROPATHY
The physical examination should focus on the extent and pattern of motor, reflex, and sensory findings. It should also differentiate between
a. Small fiber motor symptoms dominate, such as in most hereditary neuropathies, the primary dysfunction typically occurs in the motor neurons or their axons.
b. Large fiber sensory signs and consider motor weakness, ataxia, skin discoloration, and hair loss patterns.
The anatomic distribution of findings can indicate whether neuropathy affects specific nerves or nerve roots or follows a more generalized pattern.
Symmetry and length dependence is characteristic of many polyneuropathies.
Dermatomal pattern, in which abnormalities follow the distribution of specific spinal nerve roots, may indicate radiculopathy or other focal nerve disorders.
Sensory modalities can be examined using specialized tools and techniques to assess neurologic function. Small disposable pins are used to test pain sensations by applying gentle pressure or temperature changes to the skin.
Tuning forks of different frequencies may be used to evaluate vibratory sensation, with lower frequencies (eg, 128 Hz) most commonly used to test large nerve fiber function. Proprioception is assessed using joint position and Romberg tests.
Light touch sensation is typically examined using a cotton swab or the examiner’s finger, whereas monofilaments provide a more standardized approach for testing pressure sensation. Monofilaments consist of calibrated nylon fibers that bend under specific forces, allowing for a quantitative assessment of touch thresholds. When sensory dysfunction predominates, as seen in patients with sensory neuronopathies, the pathology primarily affects the sensory neurons or their processes. The distribution of sensory loss, whether it follows a length dependent or non–length-dependent pattern, can provide additional clues about the underlying mechanism. A non–length-dependent or asymmetric pattern might suggest neuronopathy affecting the dorsal root ganglia, as may be seen in autoimmune sensory
#ganglionopathy or certain paraneoplastic neuropathies.
Foot deformities, contractures, and arthritic changes are significant indicators that can help diagnose long-standing, acquired, and hereditary neuropathies such as CMT. These changes develop over time due to nerve damage and altered biomechanics, resulting in foot deformities, such as pes cavus (high arches) or hammer toes.
Skin alterations can provide valuable diagnostic clues.
Endocrinopathies associated with certain neuropathies, such as adrenoleukodystrophy or polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) syndrome, may cause distinct skin color changes.
Muscle stretch reflexes help differentiate between upper and lower motor neuron involvement. Although diminished reflexes are commonly associated with peripheral neuropathies, the presence of brisk or disproportionately hyperactive reflexes may indicate more complex underlying pathologies. For instance, myeloneuropathies may present with brisk reflexes, serving as valuable diagnostic clues for certain acquired disorders, such as vitamin B12 or copper deficiency and zinc or nitric oxide toxicity. This pattern is not exclusive to acquired conditions, as patients with some hereditary neuropathies, such as CMT type 2A, may have brisk reflexes. In cases of pure motor involvement, brisk reflexes may raise suspicion of MND, highlighting the importance of comprehensive clinical assessment.
Patients with hereditary spastic paraplegia may experience mild neuropathic symptoms alongside brisk reflexes, and prominent spasticity is not a universal feature of hereditary spastic paraplegia. Hereditary spastic paraplegia should be considered when evaluating for hereditary neuropathies.
