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 = hyperventilation syndrome/anxiety, no further neurological test is needed, and the patient can be discharged from the clinic.

3.) If symptoms are constant and the hyperventilation test is negative, do...

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 if they breathe into a paper bag (or if not available, then into their hands with minimal leak) and symptoms improve. I used to keep some paper bags available in the clinic for this purpose.

Before as...