What is your approach to patients with diffuse, patchy paresthesias affecting the head, face, lips, and/or tongue?

1.) Are the symptoms episodic (coming and going) or constant? If episodic, the likelihood of sinister neurological disease is very low.

2.) Do the hyperventilation test. If the patient has no paresthesias before the test and the symptoms are reliably reproduced by 8-10 deep breaths/min, diagnosis = ...

Paresthesias of the face, head, and lips are extremely rare as manifestations of a peripheral neuropathy, and I agree that FND, anxiety, hyperventilation, and panic are likely in most cases. With regards to HV testing, if the symptoms are reproduced, it helps the patient understand the significance ...