A Prospective Comparison of CT-Epidurogram
Between Th1-Transforaminal Epidural Injection
and Th1/2-Parasagittal Interlaminar Epidural
Injection for Cervical Upper Limb Pain
Authors: Hashizume Keiji 
Published: February 2021

Background: Cervical epidural injections for treating neck and upper limb pain are performed
by 2 methods: transforaminal and interlaminar. Many serious complications caused by inadvertent
intravascular injection have been reported with the use of cervical transforaminal epidural steroid
injection through the anterior-lateral approach. Despite international practical guidelines that have
been proposed, cervical transforaminal epidural injection is still less recommended than cervical
interlaminar epidural injection.
Objectives: The objective of this study is to introduce Th1-transforaminal epidural injection (Th1-
TFEI) through the posterior-lateral approach, compare the injectate spread in Th1-TFEI with that of
Th1/2-parasaggital interlaminar epidural injection (Th1/2-pILEI), and clarify the clinical characteristics
of Th1-TFEI.
Study Design: This research involved a prospective study of 30 patients receiving both Th1-TFEI
and Th1/2-pILEI.
Methods: Thirty patients with unilateral upper limb pain were enrolled for this prospective study.
Th1-TFEI and Th1/2-pILEI were administered on each case in random order under fluoroscopy,
and computed tomographic (CT) epidurograms were compared. Changes in circulatory dynamics,
presence of Horner’s syndrome, changes in the Numerical Rating Scale (NRS-11), and adverse events
were investigated.
Results: Patients included 15 men and 15 women and included 24 cases of cervical spine disease
and 6 cases with other upper limb pain. The Th1-TFEI group had significantly higher rates of “Th1
root filling” (100%), “ventral spread” (70.0%), and “lateral limitation” (26.7%) compared to the
Th1/2-pILEI group. In the Th1-TFEI group, cephalad spread averaged 2.97 vertebral bodies, reaching
approximately up to C6. The Th1/2-pILEI group had an average of 4.76 vertebral bodies, approximately
up to C4. The 2 groups showed significant differences in cephalad spread. Horner’s syndrome
appeared in the Th1-TFEI group at a rate of 56.7%, significantly higher than that in the Th1/2-pILEI
group at 17.2%. The presence of Horner’s syndrome showed significant correlations with “ventral
spread” and “spread up to C6.” There were no significant differences in NRS-11 improvement and
changes in circulatory dynamics between the groups. There were no major complications.
Limitations: The components of injectate were standardized; however, the needle gauge numbers
were varied. In addition, interpretation of the CT-epidurogram was not blinded. The sample size was
small; therefore, multivariate analysis was not possible.
Conclusions: CT-epidurogram comparison revealed that Th1/2-pILEI was not localized on the
injection side, and there was better dorsal spread – although ventral spread was small. Contrarily,
Th1-TFEI was localized on the injection side, and better ventral spread was shown while cephalad
spread was limited. We expected the addition of a sympathetic block effect suggested by the Horner’s
syndrome as well as the merits of the ventral spread. However, short-term clinical effects were equal
to those of Th1/2 pILEI. In future research, we need to standardize the diseases to include and to
increase the number of cases to enable evaluation of clinical effectiveness.Key words: Epidural, cervical, transforaminal, interlaminar, fluoroscopy, CT-epidurogram, dorsal, ventral, cephalad, Horner’s
syndrome