Symptomatic Outcome after Bone-only Suboccipital Decompression in Adult Patients with Chiari Type I Malformations in the Absence of Hydromyelia or Hydrocephalus

Abstract

Type I Chiari malformation presents without an associated hydromyelia in 30 to 70% of cases, yet there is no agreement regarding the optimal surgical treatment for these patients. We review our experience for treating symptomatic adult type I Chiari malformation without hydromyelia using a suboccipital bone decompression of the hindbrain and no duraplasty in 12 adult patients. Outcome was measured according to the Chicago Chiari Outcome Scale (CCOS). Nine of 12 patients were female; average age at surgery was 34.4 years (range: 17-67 years). Average duration of symptoms prior to surgery was 9.6 years (2 months-29 years). The most common symptom was head and/or neck pain (11/12 patients). All patients additionally presented with at least one non-pain symptom. Mean degree of tonsillar herniation on magnetic resonance imaging was 6.8 mm (range: 5-12 mm) below McRae's line. Operative time was on average 68 minutes (range: 47-120 minutes). No surgical complications were noted in any patient. Length of hospital stay was 2 days (1 overnight) for all patients. Mean follow-up was 167 weeks (range: 13-378 weeks). CCOS for all patients on average was 14.50 (range: 12-16). Pain symptoms underwent improvement (7/11 [63.6%]) or complete resolution (4/11 [36.4%]) in all affected patients. A shorter duration of preoperative symptoms significantly correlated with a better CCOS ( = 0.03). Degree of tonsillar herniation had no significant effect on CCOS ( = 0.67). Of non-pain symptoms, paresthesias/dysesthesias and visual symptoms improved or resolved completely in all affected patients. No patient experienced a worsening of either pain or non-pain symptoms. In the subset of adult patients with a type I Chiari malformation and no associated hydromyelia, a craniectomy without an additional opening of the dura may achieve good overall results according to the CCOS.

Stealth cranioplasty in symptomatic adult chiari 1 malformations: Experience at Bangabandhu Sheikh Mujib Medical University

“…The average score or the groups that the patients fall varies depending on several factors like the duration of symptoms, variability of symptoms, abundance of surgical techniques or range of follow up periods. 28,[33][34][35] Altogether most of the patients in our series had functional outcome considering SC alone, two third of the patients had excellent outcome. In most of the other series, the general outcome with CCOS improved gradually with time and varied noticeably depending on different factors.…”

“…Most of the studies on adult CM1 patients show that the average CCOS that could be achieved ranges between 13 to 14.5. 25,28,[33][34][35] Most of the patients in different series succeeded in achieving excellent outcome on average with good CCOS. The average score or the groups that the patients fall varies depending on several factors like the duration of symptoms, variability of symptoms, abundance of surgical techniques or range of follow up periods.…”

“…This stresses the urgency to diagnose and treat at the earliest to prevent or even to reverse the deficits in some cases. 2,28 CM1 patients usually present with myriad of symptoms, especially when they have associated SM and heterogeneity of presentations continually pose mystery. Symptoms and signs typically arise from impairment of functions involving the cerebellum, brain stem or spinal cord, alone or in combinations particularly when associated syringomyelia is present.…”