Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review

Abstract

There is growing recognition of the kyphotic clivo-axial angle (CXA) as an index of risk of brainstem deformity and craniocervical instability. This review of literature and prospective pilot study is the first to address the potential correlation between correction of the pathological CXA and postoperative clinical outcome. The CXA is a useful sentinel to alert the radiologist and surgeon to the possibility of brainstem deformity or instability. Ten adult subjects with ventral brainstem compression, radiographically manifest as a kyphotic CXA, underwent correction of deformity (normalization of the CXA) prior to fusion and occipito-cervical stabilization. The subjects were assessed preoperatively and at one, three, six, and twelve months after surgery, using established clinical metrics: the visual analog pain scale (VAS), American Spinal InjuryAssociation Impairment Scale (ASIA), Oswestry Neck Disability Index, SF 36, and Karnofsky Index. Parametric and non-parametric statistical tests were performed to correlate clinical outcome with CXA. No major complications were observed. Two patients showed pedicle screws adjacent to but not deforming the vertebral artery on post-operative CT scan. All clinical metrics showed statistically significant improvement. Mean CXA was normalized from 135.8° to 163.7°. Correction of abnormal CXA correlated with statistically significant clinical improvement in this cohort of patients. The study supports the thesis that the CXA maybe an important metric for predicting the risk of brainstem and upper spinal cord deformation. Further study is feasible and warranted.

Optimizing Alignment Parameters During Craniocervical Stabilization and Fusion: A Technical Note

“…The MAI is established at 10-20 mm, to avoid dysphagia and dyspnea. In the authors' experience, attention to precise reduction improves the outcome [7,11,12].…”

“…Correct craniocervical reduction/realignment is of paramount importance. Proper spinal alignment optimizes cerebrospinal fluid (CSF) flow through the foramen magnum, establishes the appropriate "gaze angle", avoids dysphagia and dyspnea, and, most importantly, normalizes the clival-axial angle (CXA) to reduce ventral brainstem compression [2,[4][5][6][7]. The authors introduce a direct measure of gaze angle: the orbital-axial angle (OAA) and a mandible-axial interval (MAI) metric of the pharyngeal space to avoid dyspnea and dysphagia.…”

“…To illustrate the metrics of reduction, we present a patient with signs and symptoms of the cervical medullary syndrome, which included severe head and neck pain, spasticity, weakness, sensory loss, and radiological indices of ventral brainstem compression, a kyphotic CXA, craniocervical instability, along with pathological translation between flexion and extension images [4,[7][8][9]. A CT scan demonstrated rotary C1-C2 subluxation (Fielding Type 1) upon full neck rotation [10].…”

Relations Between Foramen Magnum and Associated Structures Located Within the Skull Base of the Turkish Population

“…Ayrıca C-FM ile FMap (p<0,001, r=-0,16) ve FMt (p=0,03, r=-0,12) arasında istatistiksel olarak anlamlı, ancak zayıf negatif korelasyon olduğu tespit edildi.Kafa tabanının morfometrik ölçümleri, tanı ve uygun cerrahi seçimi sırasında klinisyenler için büyük önem taşımaktadır. Kafa tabanı ile doğrudan ilişkili olan Chiari malformasyonu, hipoplazi, kleftler, aplasia, tonsiller herniasyon ve pek çok diğer patoloji ve malformasyonlar bulunmaktadır 1,12,14,[16][17][18][19] . Bu çalışmada literatürdeki çalışmalar referans alınarak LoC, C-FM, C-D, FMap, FMt ve FMa ölçümleri yapılmıştır 1,5,[9][10][11][16][17][18][19] .…”

“…Kafa tabanı ile doğrudan ilişkili olan Chiari malformasyonu, hipoplazi, kleftler, aplasia, tonsiller herniasyon ve pek çok diğer patoloji ve malformasyonlar bulunmaktadır 1,12,14,[16][17][18][19] . Bu çalışmada literatürdeki çalışmalar referans alınarak LoC, C-FM, C-D, FMap, FMt ve FMa ölçümleri yapılmıştır 1,5,[9][10][11][16][17][18][19] . FM'un şekli ve boyutları cerrahi tekniği etkileyebilir ve bu konuda pek çok çalışma yapılmıştır 1,9,10,22 .…”