Decompression in Chiari Malformation: Clinical, Ocular Motor, Cerebellar, and Vestibular Outcome

Imaging of vertigo and dizziness: a site-based approach part 3 (Brainstem, cerebellum and miscellaneous)

Dizziness and vertigo, frequently associated with cerebrovascular origins, pose a substantial challenge in emergency medical settings due to their potential to be associated with severe underlying conditions. Sudden-onset dizziness, in particular, may be an early indicator of critical events such as stroke or transient ischemic attack (TIA). This comprehensive review encompasses the differential diagnosis of central causes of dizziness and vertigo, emphasizing the crucial role of imaging modalities in the accurate detection and assessment, including cerebrovascular diseases, inflammatory disorders, infections, and other conditions such as vestibular migraine and cervical spondylosis. It highlights the significance of advanced imaging techniques, particularly magnetic resonance imaging (MRI) and computed tomography (CT) in identifying and distinguishing these conditions.

Intraoperative neuromonitoring in Chiari I malformation surgery: a systematic review and meta-analysis

Chiari Malformation Type I (CMI) is a prevalent neurosurgical condition characterized by the descent of cerebellar tonsils below the foramen magnum. Surgery, aimed at reducing symptomatology and syrinx size, presents risks, making intraoperative neuromonitoring (IONM) a potentially vital tool. Despite its widespread use in cervical spine surgery, the utility of IONM in CMI surgery remains controversial, with concerns over increased operative time, cost, restricted anesthetic techniques and tongue lacerations. This systematic review and meta-analysis followed the Cochrane Group standards and PRISMA framework. It encompassed an extensive search through PubMed, Embase, and Web of Science up to December 2023, focusing on clinical and surgical outcomes of IONM in CMI surgery. Primary outcomes included the use of various IONM techniques, complication rates, clinical improvement, reoperation, and mortality. The review, registered at PROSPERO (CRD42024498996), included both prospective and retrospective studies, with rigorous selection and data extraction processes. Statistical analysis was conducted using R software. The review included 16 studies, comprising 1358 patients. It revealed that IONM techniques predominantly involved somatosensory evoked potentials (SSEPs), followed by motor evoked potentials (MEPs) and Brainstem auditory evoked potentials (BAEPs). The estimated risk of complications with IONM was 6% (95% CI: 2-11%; I2 = 89%), lower than previously reported rates without IONM. Notably, the clinical improvement rate post-surgery was high at 99% (95% CI: 98-100%; I2 = 56%). The analysis also showed lower reoperation rates in surgeries with IONM compared to those without. Interestingly, no mortality was observed in the included studies. This systematic review and meta-analysis indicate that intraoperative neuromonitoring in Chiari I malformation surgery is associated with favorable clinical outcomes, including lower complication and reoperation rates, and high rates of clinical improvement.

Clinical analysis of atlanto-occipital decompression in the management of chiari malformation with multi-segmental syringomyelia

Background

Chiari malformation type I with syringomyelia (CM-I-S) is a very common disease in neurosurgery. There are also various surgical methods. But it is controversial. There are few reports about children, especially the treatment of multi-segmental beaded syringomyelia. The purpose of this study was to explore the clinical effects of atlanto-occipital decompression (AOD) in the management of Chiari malformation type I (CM-I) with multi-segmental beaded syringomyelia (MSBS) in pediatric patients.

Methods

This retrospective study were pediatric patients with CM-I combined with MSBS who were treated in our hospital from January 2015 to December 2023. The patients who received the AOD treatment were screened according to inclusion and exclusion criteria. Outcomes were assessed by comparison of pre- and postoperative clinical, Chicago Chiari Outcome Scale (CCOS), the diameter and volume of the syringomyelia, morphological parameters of posterior cranial fossa (cervical spinal cord angle of medulla oblongata, CSC-MO) and complications in the enrolled children.

Results

This study ultimately included 21 eligible pediatric patients with CM-I and MSBS. All the patients successfully completed the operation, which consists of atlanto-occipital decompression, partial resection of the posterior arch of the atlas, electrocoagulation of the cerebellar tonsil, pseudomembrane resection of the central canal orifice (latch) of the spinal cord, and artificial dura mater expansion repair. No death, no relapses, no serious neurological dysfunction and other complications. At the last follow-up, the clinical symptoms of all patients basically disappeared. The results of magnetic resonance imaging (MRI) showed that the average preoperative cerebellar tonsillar hernia was 12.4 ± 4.6 mm, and the postoperative were all above the foramen magnum. The average preoperative syringomyelia volume was 11.7 ± 3.7 cm2, and the syringomyelia disappeared or significantly shrunk after operation, with the volume unable to be accurately measured. The median preoperative CSC-MO was 132.5°, and the median postoperative CSC-MO was 150°, with a significant difference. The median preoperative pain and non-pain score of CCOS was 4 and 3 respectively. The symptoms disappeared after operation, and the score was 4. Only 5 children had cerebrospinal fluid leakage.

Conclusion

The AOD is safe and effective in CM-I with MSBS in pediatric patients. Pseudomembrane resection of the central canal orifice (latch) of the spinal cord is crucial for the treatment of syringomyelia.

Early Postoperative Magnetic Resonance Imaging Findings Related to Electrocauterization for Cerebellar Reduction During Chiari Decompression Surgery

BACKGROUND

Cerebellar tonsillar reduction or resection can be performed as part of the surgical management of Chiari type 1 malformation when it is accompanied by symptomatic brainstem compression or syringomyelia. The purpose of this study is to characterize the early postoperative magnetic resonance imaging (MRI) findings in patients with Chiari type 1 malformations who undergo cerebellar tonsillar reduction via electrocautery.

METHODS

The extent of cytotoxic edema and microhemorrhages demonstrated on MRI scans obtained within 9 days following surgery was assessed and correlated with neurological symptoms.

RESULTS

Cytotoxic edema was found on all postoperative MRI examinations included in this series, with superimposed hemorrhage in 12 of 16 patients (75%) and was primarily located along the margins of the cauterized inferior cerebellum. Cytotoxic edema was present beyond the margins of the cauterized cerebellar tonsils in 5 of 16 patients (31%) and was associated with new focal neurological deficits in 4 of 5 patients (80%).

CONCLUSION

Cytotoxic edema and hemorrhages along the cerebellar tonsil cautery margins can be expected findings in early postoperative MRI in patients who undergo Chiari decompression accompanied by tonsillar reduction. However, the presence of cytotoxic edema beyond these regions can be associated with new focal neurological symptoms.

Audiovestibular Findings in a Cohort of Patients with Chiari Malformation Type I and Dizziness

Chiari Malformation Type I (CM1) is a neurological condition in which the cerebellar tonsils extend past the foramen magnum. While many studies have reported dizziness symptoms in patients with CM1, the prevalence of peripheral labyrinthine lesions is largely unknown. This study aimed to comprehensively describe the audiovestibular phenotype in a cohort of patients with CM1 expressly referred for dizziness. Twenty-four patients with CM1 and a complaint of dizziness/vertigo were evaluated. Hearing and auditory brainstem tract function were essentially normal. While vestibular abnormalities were most prevalent during rotational testing (33%), abnormal functional balance was the most common finding (40%). Patients with CM1 had a greater likelihood of exhibiting an abnormal sensory organization test (SOT) postural stability score for fixed platform conditions, and for the somatosensory analysis score. While no significant associations were identified between tonsillar ectopia extent and any vestibular/balance outcome measure, a significant negative association was identified between neck pain and the somatosensory sensory analysis score. Abnormal functional balance in the somatosensory domain was remarkable, with poorer scores associated with neck pain. An isolated peripheral vestibulopathy was present in only 8% of patients. Despite the low prevalence of vestibulopathy, vestibular/balance assessment is warranted to identify patients who may benefit from referral to specialized medical disciplines.

Exploring the prognostic differences in patients of Chiari malformation type I with syringomyelia undergoing different surgical methods

Background

The best surgical treatment of Chiari malformation patients with syringomyelia remains controversial, and whether cerebellar tonsillectomy should be performed has not been decided.

Objective

To evaluate the efficacy of posterior fossa decompression with duraplasty (PFDD) and Posterior fossa decompression with resection of tonsils (PFDRT) in patients of Chiari malformation type I (CM-I) with syringomyelia and explore relevant factors affecting prognosis.

Patients and methods

We retrospectively analyzed 182 adult patients of CM-I with syringomyelia who underwent PFDD or PFDRT over a 6-year period, and analyzed their clinical manifestations, imaging features, and follow-up data. Clinical outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS), and imaging outcomes were assessed using the syrinx remission rate. Difference comparisons were performed to compare the differences between different surgical groups. Influencing factors associated with outcome were investigated using bivariate analysis and multiple linear regression analysis.

Results

There were statistically significant differences in CCOS score (p = 0.034) and syrinx remission rates (p = 0.046) between the PFDRT group and the PFDD group after surgery. Regression analysis showed that preoperative motor dysfunction, cerebellar-related symptoms and different surgical methods may have influenced the CCOS score and that brainstem-related symptoms and age may have influenced the syrinx remission rates in the total patient group (p < 0.05). Regression analysis showed that the duration of symptoms, cerebellar-related symptoms and preoperative syrinx diameter may have influenced the CCOS score and that the preoperative cerebellar tonsillar hernia distance may have influenced the postoperative syrinx remission rate in the PFDRT group (p < 0.05). Age and length of hospital stay may have influenced the CCOS score, and brainstem-related symptoms and age may have influenced the syrinx remission rates in the PFDD group (p < 0.05).

Conclusion

This study showed that the CCOS score in the PFDRT group was better than that in the PFDD group. Preoperative motor dysfunction, cerebellar-related symptoms, and different surgical methods in patients of CM-I with syringomyelia affected postoperative CCOS score. Both the duration of symptoms and the age of the patients should be actively considered as factors influencing prognosis. Symptomatic CM-I patients with syringomyelia should undergo surgical treatment as early as possible.

Headache characteristics and postoperative course in Chiari I malformation

Background

Chiari I malformation typically presents with cough headache. However, migraine-like or tension-type-like headaches may also occur. There are limited publications on Chiari I malformation-associated headache semiologies and the effect of foramen magnum decompression on different headache types.

Methods

A retrospective analysis complemented by structured phone interviews was performed on 65 patients with Chiari I malformation, treated at our hospital between 2010 and 2021. Headache semiology (according to ICHD-3), frequency, intensity, and radiological characteristics were evaluated pre- and postoperatively.

Results

We included 65 patients. 38 patients were female and 27 male. Mean age was 43.9 ± 15.7 years. Headache was predominant in 41 patients (63.0%). Twenty-one patients had cough headache and 20 had atypical headache (12 migrainous, eight tension-type headache-like). Thirty-five patients with headache underwent surgery. Frequency, intensity, and analgesic use was significantly reduced in cough headache (p < 0.001). Atypical headaches improved less (p = 0.004 to 0.176). Exploratory analysis suggested that larger preoperative tonsillar descent correlated with larger postoperative headache intensity relief (p = 0.025).

Conclusion

Decompression was effective in Chiari I malformation-related cough headache. Atypical headache responded less well, and the causal relation with Chiari I malformation remains uncertain. For atypical headache, decompression should only be considered after failed appropriate preventive therapy and within an interdisciplinary approach involving a neurologist.

Downbeat nystagmus: a clinical review of diagnosis and management

PURPOSE OF REVIEW

This review will extensively cover the clinical manifestations, causes, diagnostic evaluation, and management strategies of downbeat nystagmus (DBN).

RECENT FINDINGS

Historically, MRI to assess for structural lesions at the cervicomedullary junction has been the primary diagnostic test in the evaluation of DBN since the 1980s. In recent years, there is increasing awareness of nonstructural causes of DBN including gluten ataxia, nutritional deficiencies, and paraneoplastic syndromes, among others. Medical management with aminopyridines has become first-line therapy in addition to disease-specific therapies.

SUMMARY

DBN is a common form of acquired nystagmus and the differential diagnosis remains broad, including both benign and potentially fatal causes. For practical purposes, the causes can be categorized as structural vs. nonstructural with MRI as the ideal, initial diagnostic study to differentiate the two. General therapeutic options include pharmacotherapy to enhance Purkinje cell function, strabismus surgery or prisms to shift null points, and behavioural changes. Disease-specific treatment is necessarily broad, though a significant proportion of patients will be idiopathic.

Exploring hand dexterity in children with myelomeningocele

PURPOSE

To assess hand dexterity in children with myelomeningocele (MMC) and to explore factors related to hand dexterity in these children.

METHODS

Ninety-four children with myelomeningocele, aged 4 to 18 years, were assessed. Demographic characteristics, disease factors, visual perception (Beery test of Visual Motor Integration), cognition (WeeFunctional Independence Measure), and self-care (Pediatric Evaluation of Disability Inventory) were assessed in relation to the Nine-Hole Peg Test (9HPT) for hand dexterity using Spearmen correlations and linear regressions.

RESULTS

The children's performance on the 9HPT in both hands was significantly slower than the norms for their age groups. Children without a shunt showed significantly better function in both hands (p = .005) than those with a shunt. Factors most related to hand dexterity were neurological spinal level of MMC, presence of shunt, age, cognitive ability, and years of mother's education.

CONCLUSION

Children with MMC appear to have poorer hand skills than typically developed children, which was related to pathology as well as functional and environmental factors. When addressing hand dexterity in children with MMC, it is important that rehabilitation professionals continue to work with these children as they get older, and put greater emphasis on parent education using materials that are adapted to varying educational levels.

Symptom outcome after craniovertebral decompression for Chiari type 1 malformation without syringomyelia

BACKGROUND

Specific symptom outcomes after craniovertebral decompression for patients with Chiari type 1 malformation, without accompanying syringomyelia, are not well characterised and poorly reported.

METHODS

We performed a retrospective review of all patients diagnosed with Chiari type 1, without syringomyelia, who underwent craniovertebral decompression in our unit.

RESULTS

We identified 129 individuals with a minimum of 2 years' follow-up. The most common pre-operative symptoms were pressure dissociation headaches (78%), visual disturbances (33%), dizziness/balance disturbances (24%) and blackouts (17%). The symptoms most likely to respond to surgery included Valsalva-induced headache (74% response, p < 0.0001) and blackouts (86% response, p < 0.001).

CONCLUSIONS

After successful craniovertebral decompression, most patients presenting with pressure dissociation headaches and blackouts will improve. However, the large variety of other symptoms patients often present with may not improve after surgery.

The 270° Circumferential Microsurgical Decompression of the Foramen Magnum in Adult Chiari Malformation Type I: Single Surgeon Series of 130 Patients with Syringomyelia, Neurologic, and Headache Outcomes

OBJECTIVE

Chiari malformation type I (CM-I) is a craniocervical junction disorder associated with descent of the cerebellar tonsils >5 mm. The prevalence of CM-I is common, including 0.5%-3.5% in the general population, 0.56%-0.77% on magnetic resonance imaging, and 0.62% in anatomic dissection studies. We sought to measure our surgical outcomes related to resolution/improvement of headaches, neurologic outcomes, and syringomyelia compared with reported adult CM-I studies from 2000-2019.

METHODS

From December 2003 to June 2018, the first author (K.I.A.) performed 270° circumferential decompression on adult (>18 years) patients with CM-I. At admission and follow-up, all parameters were numerically evaluated; headaches were self-reported on the visual analog scale, neurologic condition was evaluated using Karnofsky Performance Status and European Myelopathy Score, and syrinx width (if present) was measured on magnetic resonance imaging by grades I-IV. All parameters were analyzed, compared, and statistically tested. We compared results with our previously reported and updated systematic review of operative adult CM-I studies (studies from 2000 to 2019).

RESULTS

In our series, 118/121 (98%) experienced headache improvements and 100% experienced neurologic improvements. Complete syrinx resolution was experienced by 35/43 (81%); 8 (19%) showed significant improvement. In data from reported studies (2000-2019), only 79% experienced headache resolution, 77% improvement of neurologic status, and 74% resolution/improvement of syrinx (mean).

CONCLUSIONS

Our modified 270° circumferential microsurgical foramen magnum decompression for adult CM-I appears to be beneficial in improvement of outcomes, namely in resolution of the syrinx, neurologic symptoms, and headaches. We also confirm the association of body mass index with CM-I. Further studies are needed to confirm our results.

Tonsillectomy with modified reconstruction of the cisterna magna with and without craniectomy for the treatment of adult Chiari malformation type I with syringomyelia

BACKGROUND

In light of the controversies regarding the surgical treatment of adult Chiari malformation type I (CM-I) with syringomyelia, a retrospective study was conducted to evaluate the safety and efficacy of tonsillectomy followed by modified reconstruction of the cisterna magna with or without craniectomy.

METHODS

Between 2008 and 2017, 78 adult CM-I patients (36 males and 42 females, mean age 40.6 years old) with syringomyelia were treated with posterior fossa decompression (PFD) with tonsillectomy and modified reconstruction of the cisterna magna. Patients were divided into two study groups: group A (n = 40) underwent cranioplasty with replacement of the bone flap; group B (n = 38) underwent suboccipital craniectomy. Neurological outcomes were evaluated by traditional physician assessment (improved, unchanged, and worsened) and the Chicago Chiari Outcome Scale (CCOS). Syringomyelia outcomes were assessed radiologically.

RESULTS

The procedure was successfully performed in all patients, and restoration of normal cerebrospinal fluid (CSF) flow was confirmed by intraoperative ultrasonography. The median postoperative follow-up was 20.3 months (range 18-60 months). Clinical improvement was evident in 66 (84.6%) patients, with no significant differences between the two groups (85.0% vs. 84.2%, P = 0.897). According to the CCOS, 36 patients (90.0%) in group A were labeled as "good" outcome, compared with that of 34 (86.8%) in group B (P = 0.734). Improvement of syringomyelia was also comparable between the groups, which was observed in 35 (87.5%) vs. 33 (86.8%) patients (P = 0.887). The postoperative overall (7.5% vs. 23.7%, P = 0.048) and CSF-related (2.5% vs. 18.4%, P = 0.027) complication rates were significantly lower in group A than group B.

CONCLUSIONS

Tonsillectomy with modified reconstruction of the cisterna magna without craniectomy seems to be a safe and effective surgical option to treat adult CM-I patients with syringomyelia, though future well-powered prospective randomized studies are warranted to validate these findings.

Perverted Downward Corrective Saccades During Horizontal Head Impulses in Chiari Malformation

The mechanism of perverted vertical responses during horizontal head impulse tests (HITs) requires further elucidation. A 47-year-old woman with a Chiari malformation showed alternating skew deviation, downbeat nystagmus with an increasing slow phase velocity, impaired smooth pursuit, and upward ocular deviation during horizontal HITs and corrective downward saccades in the presence of normal bithermal caloric tests and intact tilt suppressions of the post-rotatory nystagmus. These findings suggest dysfunction of the inferior cerebellum including the tonsil, nodulus, and uvula. We propose that disruption of signals from the medial part of the vestibulocerebellum, which normally inhibits the lateral and anterior canal pathways, may elicit an upward misdirection of the eye velocity during rapid horizontal head rotation. Otherwise, the Chiari malformation may have directly affected the brainstem structures involved in the direction matrix of the vestibulo-ocular reflex.

Outcomes and complications for individual neurosurgeons for the treatment of Chiari I malformation at a children's hospital

PURPOSE

The aim of this study was to evaluate the outcomes and complications for individual surgeons at British Columbia Children's Hospital for the treatment of Chiari I Malformation (CMI) in children.

METHODS

This was a retrospective review of patients with CMI who had surgery from 1986 to 2015. We assessed the Chicago Chiari Outcome Scores (CCOS) and complication rates by surgeon.

RESULTS

Seventy patients, 38 males and 32 females, underwent posterior fossa decompression including 14 extradural and 56 intradural approaches. Syringomyelia was present in 74.3%. Most syringomyelia improved with no difference between intradural and extradural surgeries. After initial surgery, 13 patients (18.6%) had complications including 2/14 (14.3%) of extradural and 11/56 (19.6%) of intradural surgeries. Two patients required surgical intervention for complications whereas 11 had transient complications. The complication rate by surgeon ranged from 11 to 20% for extradural (2 surgeons only) and 10.5 to 40% for intradural surgeries (4 surgeons). The CCOS ranged from 12 to 15 for extradural and 6 to 16 for intradural. The CCOS ranges for surgeons 1 and 2 were 12-15 and 13-15 respectively for extradural. The CCOS ranges for surgeons 1, 2, 3, and 4 were 12-16, 6-15, 12-16, and 12-16 respectively for intradural. Thirteen patients had a second surgery for CMI. The final CCOS was good in 86% and moderate in 14%.

CONCLUSION

There was variability in surgeries performed at BCCH by different surgeons, with variations in CCOS and complication rates. This information is important during decision making, consent process, and for quality improvement.

Clinical diagnosis-part II: what is attributed to Chiari I

PURPOSE

Chiari malformation type I is identified as radiological appearance of cerebellar tonsil herniation below the foramen magnum. The wide spectrum of clinical manifestations variably associated sometimes encompasses signs and symptoms whose correlation with the malformation remains debatable. However, a correct clinical framework is relevant in tailoring the strategy of management, and in particular, establishing the appropriate surgical intervention.

METHODS

An analysis of relevant articles on this issue was performed, involving both single case reports and case series. The papers were obtained from electronic databases including PubMed/MEDLINE and Google Scholar, as well as direct contact with some authors.

RESULTS

This review focuses on those unusual clinical pictures attributed to Chiari malformation type I (CMI), investigating their actual relationship with the morphological condition. Supposed physiopathogenetic mechanisms and clinical relevance are discussed along with an analysis on the surgical indications and results.

CONCLUSION

There is no clear explanation on why some patients may exhibit uncommon symptoms, often in association with the most frequent ones, but even reported as single initial clinical occurrence. Their actual incidence may have been roughly underestimated in the literature so far, because of wide heterogeneity of selection and analysis among different studies. Most of the authors appear sharing the impression that CMI surgical decompression plays a significant role in controlling the majority of these unusual symptoms, stressing their actual occurrence in relation with the malformation. A routinely multidisciplinary clinical approach has become advisable to encompass the diversity of conditions potentially associated with CMI and improve the care of CMI patients.