Primary steps for primary care: Numbness and sensory changes in pediatric patients
Sensory changes in pediatric patients can be difficult to evaluate, depending on patient age and cooperation. They often occur in a length-dependent fashion, commonly starting with the tips of the toes, because the longest nerves in the peripheral nervous system supply them. In some patients, sensory changes are more transient, and occur at sites where nerves are easily compressed (from crossing legs, leaning on elbows, etc., for extended periods).
Sensory changes can involve numbness and tingling (paresthesias) or may present with a loss of proprioception, causing gait abnormalities or falls. Particularly in the setting of a positive family history, inherited neuropathies should be a consideration for pediatric patients presenting with sensory changes.
- Assess sensation in multiple modalities:
- Light touch/pinprick testing evaluates smaller nerve fibers
- Vibration/proprioception testing evaluates larger nerve fibers
- Assess for deep tendon reflexes - diminished Achilles tendon reflex can indicate involvement of larger nerve fibers; decreased or absent reflexes can be concerning for demyelinating diseases such as Guillain-Barre syndrome (GBS)
Initial lab workup for sensory changes in children can include assessing for reversible causes of neuropathy:
- CBC, CMP
- Vitamin levels including B12, B6, D
- HgbA1C (diabetic neuropathy is less common in children but can still be seen)
There are multiple medications effective for treating neuropathic pain. Notably these are typically most helpful to minimize paresthesias, but do not change the sometimes bothersome sensation of numbness. These medications are symptomatic relief and do not address the underlying cause of symptoms. They do not interfere with our neurologic evaluation so they can be started while awaiting an appointment with a specialist.
- Gabapentin for sedation and mood effects can be limiting for some patients, but many require a BID or TID dosing schedule for efficacy. Tolerance of sedation varies significantly from patient to patient.
- Pregabalin can be used as an alternative if gabapentin is not tolerated or not effective.
- Duloxetine can be especially helpful with concurrent mood disorders and allows for once-daily dosing.
When to refer to Neurology:
- When there are ascending sensory changes progressing over days to weeks, these patients will need rapid emergency department (ED) evaluation to rule out acute inflammatory demyelinating polyradiculopathy (AIDP), also commonly known as GBS. This is particularly true if changes in deep tendon reflexes or accompanying weakness is noted. There are many GBS variants that may present atypically in terms of symptom progression, so if there is a concern for possible GBS, advise erring on the side of caution and referring the patient to be evaluated in the ED.
- For patients with more slowly-progressive or stable neuropathy, a referral to neurology/neuromuscular medicine to evaluate for hereditary neuropathies is appropriate. If numbness is transient and occurs at compressible sites, conditions such as hereditary neuropathy with liability to pressure palsies (HNPP) are a consideration.
- Using specialty testing, you can counsel patients to potentially anticipate when referring to Neurology for sensory changes.
Nerve conduction studies and electromyography:
Nerve conduction studies (NCS) involve the use of recording electrodes and an electrical stimulus to measure the response of both motor and sensory nerves in the arms and legs. This test can be helpful in evaluating sensory changes but does not necessarily provide insight on etiology. NCS is limited because only larger sensory nerve fibers (sural and superficial peroneal in the lower extremity specifically) can typically be evaluated. Patients with small fiber neuropathies will have normal nerve conduction testing. These fibers cannot be measured on standard nerve conduction studies. Notably NCS can be uncomfortable and is sometimes difficult for younger patients to tolerate.
Electromyography (EMG) involves insertion of a small needle into various muscles to assess irritability and to measure motor unit amplitude and duration. This testing can demonstrate signs of acute or chronic neuropathy even when nerve conduction testing is normal. Some degree of patient cooperation is required for this testing.
Genetic panels often are utilized as an essential part of our neurologic evaluation of neuropathy. Be wary of solely relying on neuromuscular focused panels, as many omit relevant neuropathy genes such as PMP22, the most common gene causing Charcot-Marie-Tooth disease and HNPP. Comprehensive neuropathy panels are most appropriate when the concern is sensory in nature.