Vitamin B6 deficiency as a cause of polyneuropathy in POEMS syndrome: rapid recovery with supplementation in two cases

Figures & data

Figure 1. Clinical course of two POEMS patients with vitamin B6 deficiency. The dotted lines represent the lower limit of normal for serum vitamin B6. ALT: alanine aminotransferase; ASCT: autologous stem cell transplantation; AST: aspartate aminotransferase; NCS₁: nerve conduction study (before VB6 administration); NCS₂: nerve conduction study (after VB6 administration); OP: operation; PPH: pyridoxal phosphate hydrate; RT: radiation therapy; THAL + DEX: thalidomide + dexamethasone; VB6: vitamin B6; VEGF: vascular endothelial growth factor; VRD: bortezomib + lenalidomide + dexamethasone

Table 1. Nerve conduction studies before and after vitamin B6 supplementation.

				Case 1		Case 2
Nerve	Site		Limit of normal values	Before VB6 supplementation	After VB6 supplementation	Before VB6 supplementation	After VB6 supplementation
				Left	Left	Right	Right
Median nerve	Wrist-elbow	MCV	>48 m/s	23.9	30.2	44.3	52.6
		Amp	>5 mV	2.07	4.61	9.42	3.73
		DL	<4.5 ms	14.52	11.76	8.88	7.89
		FWL	<31.4 ms	48.7	47.3	24.4	20.0
		FWO		6%, 1/16	94%, 15/16	100%, 16/16	100%, 16/16
Ulnar nerve	Wrist-elbow groove	MCV	>46 m/s	29.2	37.9	45.1	59.8
		Amp	>4.7 mV	2.68	4.29	6.41	5.79
		DL	<3.6 ms	18.06	12.72	8.79	7.62
		FWL	<31.7 ms	N/A	46.8	30.9	28.9
		FWO		0%, 0/16	69%, 11/16	100%, 16/16	100%, 16/16
Tibial nerve	Ankle-popliteal	MCV	>36 m/s	N/A	N/A	31.8	39.9
		Amp	>5.6 mV	N/A	N/A	5.43	7.67
		DL	<5.9 ms	N/A	N/A	15.8	13.1
		FWL	<56.8 ms	N/A	N/A	67.9	54.4
		FWO		N/A	N/A	100%, 16/16	100%, 16/16
Peroneal nerve	Ankle-head of fibula	MCV	>37.1 m/s	N/A	N/A	30.1	41.6
		Amp	>0.7 mV	N/A	N/A	1.57	1.21
		DL	<6.2 ms	N/A	N/A	14.35	11.1
		FWL	<55.3 ms	N/A	N/A	62.9	52.8
		FWO		N/A	N/A	94%, 15/16	100%, 16/16

Notes: Case1: Nerve conductions studies (NCS) showed improvements in motor conduction velocity, amplitude, distal latency, F-wave latency, and F-wave occurrence in the Median and Ulnar nerves before and after VB6 supplementation. NCS was not performed in the lower extremities. Case 2: NCS showed improvements in motor conduction velocity, distal latency, and F-wave latency in the Median, Ulnar, Tibial, and Peroneal nerves before and after vitamin B6 supplementation. Amp: amplitude; DL: distal latency; FWL: F-wave latency; FWO: F-wave occurrence; MCV: motor conduction velocity; VB6: vitamin B6.

Data availability statement

Data from this study are available from the corresponding author, Hajime Yasuda.