Recrudescence of the syringomyelia after surgery of Chiari malformation type 1 with duraplasty

New histopathological evidence for the relationship between hydromyelia and hydrocephalus following subarachnoid hemorrhage: An experimental study

Objectives

Subarachnoid hemorrhage (SAH) is a serious pathology with a high death and morbidity rate. There can be a relationship between hydromyelia and hydrocephalus following SAH; however, this subject has not been well investigated.

Materials and Methods

Twenty-four rabbits (3 ± 0.4 years old; 4.4 ± 0.5 kg) were used in this study. Five of them were used as the control, and five of them as the SHAM group. The remaining animals (n = 14) had been used as the study group. The central canal volume values at the C1-C2 levels, ependymal cells, numbers of central canal surfaces, and Evans index values of the lateral ventricles were assessed and compared.

Results

Choroid plexus edema and increased water vesicles were observed in animals with central canal dilatation. The Evans index of the brain ventricles was 0.33 ± 0.05, the mean volume of the central canal was 1.431 ± 0.043 mm3, and ependymal cells density was 5.420 ± 879/mm2 in the control group animals (n = 5); 0.35 ± 0.17, 1.190 ± 0.114 mm3, and 4.135 ± 612/mm2 in the SHAM group animals (n = 5); and 0.44 ± 0.68, 1.814 ± 0.139 mm3, and 2.512 ± 11/mm2 in the study group (n = 14). The relationship between the Evans index values, the central canal volumes, and degenerated ependymal cell densities was statistically significant (P < 0.05).

Conclusions

This study showed that hydromyelia occurs following SAH-induced experimental hydrocephalus. Desquamation of ependymal cells and increased cerebrospinal fluid secretion may be responsible factors in the development of hydromyelia.

Effect of modified clivoaxial angle on surgical decision making and treatment outcomes in patients with Chiari malformation type 1

Introduction

Chiari malformation type 1 (CM1), a complex pathological developmental disorder of the craniovertebral junction, is typically characterized by herniation of the cerebellar tonsils from the foramen magnum. Treatment using posterior fossa decompression alone without taking the ventral cervico-medullary compression into consideration may lead to unsatisfactory treatment outcomes. The current study evaluated the utility of the modified clivoaxial angle (MCAA) in assessing ventral compression and also examined its effect on treatment outcomes.

Method

This retrospective study included 215 adult patients who underwent surgical treatment for CM1 at one medical center over a 10-year period. The following surgical techniques were used to decompress the posterior fossa: (a) PFD: bone removal only; (b) PFDwD: bone removal with duraplasty; and (c) CTR: cerebellar tonsil resection. The morphometric measurements of the craniovertebral junction (including MCAA) were recorded using preoperative images, and the postoperative clinical status was evaluated using the Chicago Chiari outcome scale (CCOS).

Results

MCAA was positively correlated with the CCOS score and also independently predicted treatment outcome. To enable Receiver operating characteristic (ROC) curve analysis of CCOS scores, the patients were divided into three groups based on the MCAA cut-off values, as follows: (a) severe (n = 43): MCAA ≤ 126; (b) moderate (n = 86): 126 < MCAA ≤ 138; and (c) mild (n = 86): MCAA > 138. Group a exhibited severe ventral cervico-medullary compression (VCMC), and their CCOS scores for the PFD, PFDwD, and CTR groups were 11.01 ± 1.2, 11.24 ± 1.3, and 13.01 ± 1.2, respectively (p < 0.05). The CCOS scores increased with widening of the MCAA angle in all surgical groups (p < 0.05). Furthermore, patients with mild MCAA (>138°) exhibited 78% regression of syringomyelia, and this was significantly greater than that observed in the other groups.

Discussion

MCAA can be used in the selection of appropriate surgical techniques and prediction of treatment outcomes, highlighting the importance of preoperative evaluation of ventral clivoaxial compression in patients with CM1.

Age- and gender-related radiological changes of the cervical spine: A study with largest magnetic resonance imaging database of 5672 consecutive patients

Background

The morphological features of the cervical spine are an essential issue. This retrospective study aimed to investigate the structural and radiological changes in the cervical spine.

Materials and Methods

A total of 250 patients with neck pain but no apparent cervical pathology were selected from a database of 5672 consecutive patients undergoing magnetic resonance imaging (MRI). MRIs were directly examined for cervical disc degeneration. These include Pfirrmann grade (Pg/C), cervical lordosis angle (A/CL), Atlantodental distance (ADD), the thickness of transverse ligament (T/TL), and position of cerebellar tonsils (P/CT). The measurements were taken at the positions of T1- and T2-weighted sagittal and axial MRIs. To evaluate the results, patients were divided into seven age groups (10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70, and over).

Results

In terms of ADD (mm), T/TL (mm), and P/CT (mm), there was no significant difference among age groups (P > 0.05). However, in terms of A/CL (degree) values, a statistically significant difference was observed among age groups (P < 0.05).

Conclusions

Intervertebral disc degeneration was more severe in males than in females as age increased. For both genders, cervical lordosis, decreased significantly as age increased. T/TL, ADD, and P/CT did not significantly differ with age. The present study indicates that structural and radiological changes are possible reasons for cervical pain at advanced ages.

Interlayer dural split technique for Chiari I malformation treatment in adult-Technical note

OBJECTIVE

To present an alternative surgical technique in treating cases of Chiari I Malformation with mild-to-moderate syringomyelia after decompressive suboccipital craniectomy: incising only the outer layer of the dura mater, then dissecting it from the inner layer without opening the latter.

PATIENTS AND METHODS

We utilized this technique in a short series of three cases who were admitted to our department for mild symptoms such as intermittent headache and dissociated sensory loss in the upper limbs, caused by a Chiari Malformation Type I. The patients were placed in the sitting position. We performed a reduced median suboccipital craniectomy and resection of the posterior arch of C1 adapted to the level of tonsil descent, from a limited superior half to complete resection. Afterward, we incised the outer dural layer, while sparing the inner one. Using a fine dissector, we then split apart the outer and inner layers to the margin of the craniectomy. Through the transparency of the inner layer and the arachnoid, the cerebellum and the medulla were visible and pulsating. An autologous fascia duraplasty was then performed.

RESULTS

The postoperative course was favorable in all cases, the patients being discharged without any deficits and with complete symptom resolution. Follow-up at 3, 6, and 12 months after surgery revealed a significant reduction in brainstem compression and syringomyelia.

CONCLUSIONS

Interlayer dural split technique can be used effectively in treating symptomatic cases of type I Chiari malformation in adults, with mild-to-moderate syringomyelia. It is less invasive than opening the dura and possibly more effective than decompressive craniectomy and C1 laminectomy alone. This technique must be validated in a larger case-control series.