Table 2.

Designs of studies using intrathecal methylprednisolone injection to treat PHN

Study	Study design	Inclusion criteria	Groups	N	Route	Dose	Outcome	Funding
Kikuchi et al.[9]	RCT	Intractable PHN (pain > 1 year)	IT MP, epidural MP	14, 15	IT, epidural	IT: 3 mL of 2% lidocaine and 60-mg MP; Epidural: 5 mL of 2% lidocaine and 60-mg MP (QW*4)	≥50% global pain relief: IT 92.3% vs. epidural 16.7% (P < 0.01).	The work was performed in the Department of Anesthesiology, University of Hirosaki, and supported in part by grants-in-aid for Scientific Research No. 08457399 (Department of Education, Japan).
							Persistent reductions in pain, lancinating pain, and allodynia for 24 weeks in IT group (P < 0.005).
Kotani et al.[6]	RCT, blinded	Intractable PHN (pain > 1 year)	MP-lidocaine, lidocaine, and no treatment	89, 91, 90	IT	3 mL of 3% lidocaine, 60 mg of MP (QW*4)	≥50% global pain relief. Greater improvement in the severity of burning and lancinating pain, allodynia, and areas of maximal pain and allodynia in the MP-lidocaine group for 2 years (P < 0.001).	Supported by a grant-in-aid for Scientific Research No. 08457399 from the Ministry of Education, Tokyo, Japan.
Rijsdijk et al.[7]	RCT	Intractable PHN (pain > 6 months), VAS score ≥ 4	MP-lidocaine and lidocaine alone	6, 4	IT	MP 60 mg, lidocaine 60 mg, or lidocaine 60 mg only (QW*4)	VAS scores for global pain and lancinating pain decreased significantly in lidocaine group. Analgesic use unchanged. *The trial was stopped because of safety concerns and futility of IT MP	None

IT = intrathecal, MP = methylprednisolone, NS = normal saline, QOW*4 = once every 2 weeks for four times