Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization

Abstract

A great deal of literature has drawn attention to the "complex Chiari," wherein the presence of instability or ventral brainstem compression prompts consideration for addressing both concerns at the time of surgery. This report addresses the clinical and radiological features and surgical outcomes in a consecutive series of subjects with hereditary connective tissue disorders (HCTD) and Chiari malformation. In 2011 and 2012, 22 consecutive patients with cervical medullary syndrome and geneticist-confirmed hereditary connective tissue disorder (HCTD), with Chiari malformation (type 1 or 0) and kyphotic clivo-axial angle (CXA) enrolled in the IRB-approved study (IRB# 10-036-06: GBMC). Two subjects were excluded on the basis of previous cranio-spinal fusion or unrelated medical issues. Symptoms, patient satisfaction, and work status were assessed by a third-party questionnaire, pain by visual analog scale (0-10/10), neurologic exams by neurosurgeon, function by Karnofsky performance scale (KPS). Pre- and post-operative radiological measurements of clivo-axial angle (CXA), the Grabb-Mapstone-Oakes measurement, and Harris measurements were made independently by neuroradiologist, with pre- and post-operative imaging (MRI and CT), 10/20 with weight-bearing, flexion, and extension MRI. All subjects underwent open reduction, stabilization occiput to C2, and fusion with rib autograft. There was 100% follow-up (20/20) at 2 and 5 years. Patients were satisfied with the surgery and would do it again given the same circumstances (100%). Statistically significant improvement was seen with headache (8.2/10 pre-op to 4.5/10 post-op, p < 0.001, vertigo (92%), imbalance (82%), dysarthria (80%), dizziness (70%), memory problems (69%), walking problems (69%), function (KPS) (p < 0.001). Neurological deficits improved in all subjects. The CXA average improved from 127° to 148° (p < 0.001). The Grabb-Oakes and Harris measurements returned to normal. Fusion occurred in 100%. There were no significant differences between the 2- and 5-year period. Two patients returned to surgery for a superficial wound infections, and two required transfusion. All patients who had rib harvests had pain related that procedure (3/10), which abated by 5 years. The results support the literature, that open reduction of the kyphotic CXA to lessen ventral brainstem deformity, and fusion/stabilization to restore stability in patients with HCTD is feasible, associated with a low surgical morbidity, and results in enduring improvement in pain and function. Rib harvest resulted in pain for several years in almost all subjects.

Keywords: Cervical medullary syndrome; Clivo-axial angle; Craniocervical instability; Ehlers-Danlos syndrome.

Conflict of interest statement

One of the senior authors (FCH Sr.) was first author of a patent for a craniocervical stabilization device, which is currently being developed by LifeSpine, Inc. (Huntley, IL) and related patents discussing finite element analysis (spinal cord stress injury analysis) of the central nervous system, mathematical prediction of neurobehavioral change, and related devices pertinent to disorders of the craniocervical junction. The same author (FCH Sr) has donated his royalties for the craniocervical device to the Chiari Syringomyelia Foundation (CSF).

Figures

Fig. 1

The Karnofsky Performance Status Scale

Fig. 2

a The normal CXA. The normal CXA is approximately 155°, decreasing 10° in flexion and increasing 10° in extension. b The pathological clival axial angle (CXA) is more kyphotic than the normal CXA. The CXA is subtended by the posterior axial line and a line drawn along the surface of the lower third of the clivus. An angle of 135° or less is considered potentially pathological. The kyphotic CXA of 124° shown here is clearly pathological and results in a mechanical deformity and lengthening of the brainstem and upper spinal cord, as shown diagrammatically in the next image (Fig. 2c). c Diagrammatical rendering of a kyphotic CXA. In hereditary connective tissue disorders, ligamentous laxity may thus result in a kyphotic CXA in flexion, with a concurrent increase in strain (Ɛ)

Fig. 3

The Grabb, Mapstone, Oakes measurement: a measurement of 9 mm or greater implies a high risk of ventral brainstem compression

Fig. 4

Horizontal Harris Measurement (HHM): a measurement of > 12 mm represents craniocervical instability. If the HHM changes by > 2 mm between flexion and extension, then craniocervical instability is inferred

Fig. 5

Traction reduction: the surgeon stands at the head of the table, grasps the head holder, and applies 1: traction; 2: posterior translation; 3: extension, to bring the basion into correct relationship with the odontoid

Fig. 6

Intraoperative reduction: the preoperative CT (i) shows a CXA of 130°; the intra-operative fluoroscopic image after reduction (ii) shows a CXA of 146°

Fig. 7

Comparison of Karnofsky scores before surgery and at 2 and 5 years post-surgery

Fig. 8

Comparison of CXA measurements pre vs. post-surgery

Fig. 9

Opinion regarding choice of surgery

Fig. 10

Opinion regarding recommending surgery

Fig. 11

Opinion regarding improvement of quality of life

Fig. 12

Opinion regarding symptoms and limitations