If the symptoms involve hand pain and weakness and the findings are consistent with median or ulnar neuropathy, electrodiagnostic studies and/or a nerve ultrasound are warranted, Dr. Varadhachary said. If the findings are still consistent for ulnar neuropathy, carpal tunnel syndrome or tenosynovial biopsy for amyloidosis, it’s best to refer to a hand specialist.
Dr. Scofield and Dr. Varadhachary shared a mononeuropathy case example, describing a 65-year-old male with right-hand weakness and numbness that was painful and started about two years earlier. His initial treatment with gabapentin was somewhat helpful but about six months ago, he noticed that his hand appeared to be shrinking. An exam showed loss of muscle bulk of the thenar eminence and a hollowed-out space between the thumb and forefinger. He also had a steppage gait, leading him to lift one of his feet higher than normal.
When discussing the value of an electrodiagnostic study, Dr. Scofield said that would likely be useful. Dr. Varadhachary agreed and said that in this situation, give a precise description to the electromyographer of the type of testing you want. “I’d say to localize for carpal tunnel and for foot drop,” he explained.
Asymmetric & Multifocal Neuropathies
Asymmetric and multifocal neuropathies involve simultaneous or sequential damage to multiple noncontiguous nerves. “It could start with a wrist drop and then there may be a foot drop on the other side a few weeks later,” Dr. Varadhachary said.
Confluent multiple mononeuropathies may simulate a length-dependent polyneuropathy or asymmetric polyneuropathy, the presenters said.
Pain is a significant feature of asymmetric and multifocal neuropathies, particularly for those with an immune-mediated disease, he added. Motor and sensory loss, fever, weight loss and arthralgia also are common.
A comprehensive neurological exam and electrodiagnostic studies can dig deeper to find a cause. For example, for findings consistent with small fiber neuropathy and the nerve conduction and electromyography are normal, epidermal nerve fiber density with punch skin biopsy may be warranted. For findings consistent with vasculitis, neoplasm, amyloid or another infiltrative process, the presenters recommended a nerve and muscle biopsy. If the findings are still consistent with vasculitis, assess serum cryoglobulins or surrogate markers, such as positive rheumatoid factor or low C4, Dr. Scofield said.
The polyneuropathies can vary, but a few treatment recommendations include:
- For vasculitic neuropathy: immediately start high-dose systemic glucocorticoids with rituximab along with cyclophosphamide
- For immune-mediated non-vasculitic large fiber polyneuropathy: intravenous immunoglobulin (IVIG)
- For persistent pain: gabapentin, pregabalin or serotonin and norepinephrine reuptake inhibitors; also add sodium channel-blocking agents or tricyclic antidepressants
The presenters shared the case of a 36-year-old female who came to clinic complaining of two months of diffuse joint pains, myalgias and distal dysesthesias. Her initial lab tests and joint exam were normal, although her ankles were mildly swollen. Her general exam showed stocking-glove dry, warm, red skin. Her sensory exam showed normal vibration sensation but abnormal pin-prick and temperature perception. Her reflexes at the biceps and knees were easily elicitable but indeterminate at the ankles.
