Disclosures: Michael Spickler, MD: Nothing to disclose

Case Description: Patient is a 25-year-old female without pertinent medical history who presented for acute onset of ascending lower extremity paresthesias. Social history includes tobacco use but denies illicit substances. No recent illnesses or pertinent family history. The paresthesias started three days prior to admission and progressively worsened. On admission, patient noted paresthesias in both hands and bilateral lower extremities that extended to her mid thighs. No pain, dysphagia, bowel or bladder incontinence, or weakness described. Physical exam was benign except for diminished bilateral S1 reflexes and diminished vibratory sense in the distal lower extremities, proprioception was intact. Magnetic resonance imaging (MRI) of the entire neuro axis was unremarkable. Lumbar puncture was unremarkable. Infectious and inflammatory markers were negative. Electromyography was deferred due to acuity of symptoms. Patient was initially treated with intravenous steroids without improvement. Physical therapy evaluated due to mild sensory ataxia. Upon further history gathering, patient admitted to regular nitrous oxide use, or “whippets.” Patient improved with initial treatment discussed below and was discharged home with outpatient follow up.

Setting: Tertiary Hospital

Patient: 25-year-old female

Assessment/Results: Elevated homocysteine level. Normal vitamin B12 and folate level.

Discussion: Nitrous oxide use can result in a sensorimotor peripheral polyneuropathy due to functional inactivation of vitamin B12. Our patient had no objective findings of myelopathy on imaging or cerebrospinal fluid analysis. Dorsal column involvement can often be seen. Lab markers include raised levels of homocysteine with low or normal B12 levels. Patient was treated with intramuscular B12 for four weeks with significant improvement of symptoms. She continued outpatient physical therapy for sensory gait abnormalities.

Conclusion: Nitrous oxide use should be in the differential for distal symmetric sensory neuropathies. Patient’s symptoms gradually improved with treatment and physical therapy.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/distal-symmetric-peripheral-polyneuropathy-due-to-nitrous-oxide-use/