Severe C8 or T1 Symptoms after Cervical Laminoplasty and Related Factors: Are There Any Differences between C3–C6 Laminoplasty and C3–C7 Laminoplasty?

ABSTRACT

STUDY DESIGN: Retrospective study. PURPOSE: We experienced the situation wherein some patients had new-onset pain or dysesthesia around the ring and little fingers (C8 symptom) or ulnar aspect of the forearm (T1 symptom) after cervical laminoplasty (LP). We investigated the incidence and the cause of new C8 or T1 symptoms and the clinical outcomes after C3–C6 LP or C3–C7 LP. OVERVIEW OF LITERATURE: There were some reports regarding complications after cervical LP. However, there was no report regarding C8 or T1 symptoms after cervical LP. METHODS: Among the 33 patients enrolled in this study, 11 and 22 patients were treated with C3–C6 LP and C3–C7 LP, respectively. We prospectively evaluated C8 or T1 symptoms daily postoperatively for 1 week. The distance of the posterior spinal cord shifting and posterior subarachnoid space from C2 to T1 was measured by T2-weighted midsagittal magnetic resonance imaging (MRI). We evaluated pre- and postoperative axial neck pain, Japanese Orthopaedic Association (JOA) score, and JOA score improvement rate. RESULTS: C8 or T1 symptoms occurred in five and three patients with C3–C6 LP (45.5%) and C3–C7 LP (13.6%), respectively. The distance of the posterior subarachnoid space in C3–C6 LP at C7 was significantly shorter than that in C3–C7 LP at T1 on MRI 24 hours postoperatively (p=0.0448). Postoperative axial neck pain, pre- and postoperative JOA scores, and JOA score improvement rate were not significantly different. CONCLUSIONS: The incidence of C8 or T1 symptoms in C3–C6 LP was higher than that in C3–C7 LP. C8 or T1 symptoms would be caused by the posterior fila radicularia and spinal cord impingement on the intact lower end of the lamina.