Table 1

Pitfalls in the diagnosis of CIDP

Category	Compatible with CIDP	Pitfall	Alternative explanation to be considered	References
Clinical	Widespread loss of reflexes.	Only absence of ankle reflexes.	Length-dependent neuropathy.	18
	Loss of vibration sense.	Vibration sense not reduced.	Motor neuron disease.	18
	Treatment response assessed by objective scales.	Subjective or non-specific response to immunotherapy.	Placebo effect, confounding factors such as fatigue, depression.	19
	Consistent and objective improvement in muscle strength by reducing IVIg infusion interval or by other immunotherapies.	No response to immunotherapy is considered ‘refractory’.	Non-immunoneuropathy, motor neuron disease.	18
CSF	High elevation (often >100 mg/dL).	No or only mild elevation of CSF protein.	Non-specific, occurs also in, for example, spinal stenosis.	18 19
Electrophysiology	Significantly (<80% LLN) reduced conduction slowing. Conduction slowing independent of compression sites.	Misinterpretation of conduction slowing.	Conduction slowing for small potentials. Conduction slowing at compression sites.	17
	Upper limb segmental demyelination.	Abnormalities exclusively in lower extremity nerves.	Length-dependent neuropathy.	17
	Heterogeneous motor conduction slowing.	Homogeneous nerve conduction slowing.	Hereditary neuropathy.	16

CIDP, chronic inflammatory demyelinating polyneuropathy; CSF, cerebrospinal fluid; IVIg, intravenous immunoglobulin; LLN, lower limit of normal values.