Fig 1.
Spinal cord magnetic resonance imaging of case 18.
Transverse sections of spinal cord showing “V” inverted T2 hyperintensity in the cervical spinal cord (A) and ellipse-shapes T2 hyperintensity in the thoracic spinal cord (B).
Table 1.
Demographics and clinical data of the 18 patients.
Table 2.
Laboratory findings of N2O abuse resulting in peripheral neuropathy.
Fig 2.
Motor nerve conduction study results in the normal control (NC) and N2O-induced neuropathy groups.
(A) The compound muscle action potential amplitude, (B)motor conduction velocity, (C) distal latency of each motor nerve for the NC(N = 20, gray bar) and N2O-induced neuropathy groups (N = 18, black bar). Data are presented as mean ±standard error of the mean. Significant difference is indicated by ***p < 0.001,**p<0.005, *P<0.01 using Mann-Whitney U test. M, median nerve; U, ulnar nerve; P, peroneal nerve; T, tibial nerve.
Fig 3.
Sensory nerve conduction study results in the normal control (NC) and N2O-induced neuropathy groups.
(A) The sensory nerve action potential amplitude and (B) sensory conduction velocity of each sensory nerve for the NC (N = 20, gray bar) and N2O-induced neuropathy groups (N = 18, black bar). Data are presented as mean ± standard error of the mean. Significant difference is indicated by ***p < 0.001, **p<0.005, *P<0.01 using Mann-Whitney U test. M, median nerve; U, ulnar nerve; P, peroneal nerve; T, tibial nerve.
Fig 4.
Semi-thin section toluidine blue staining of sural nerve.
(A) Sural nerve biopsy showing normal large and small myelinated nerve fibers without pathological alterations. (B) Sural nerve biopsy of patients with N2O-induced peripheral neuropathy. (C) Distribution of myelinated fiber diameters is shown as a histogram with 1μm bin. Significant difference is indicated by ***p < 0.001, **p<0.005, *P<0.01.
Fig 5.
Spectrum of findings seen on sural nerve biopsies in N2O-induced peripheral neuropathy.
(A) Semi thin section stained with toluidine blue shows axon degeneration (black circle) and nerve regeneration (white circle). (B) Electron microscopy shows axon degeneration (black circle) and nerve regeneration (white circle). (C-D) Masson trichrome staining showing acute axonal degeneration and formation of myelin ovoid evident on longitudinal sections (white arrows). This patient had CD68-positive mononuclear cells within the fascicular.