Neurosurgical Advocacy in the Prevention of Neural Tube Defects: Impacting Global Fortification Policies Through Leadership, Collaboration, and Stakeholder Engagement.

The G4 Alliance and its member organizations formed a delegation that participated in the 76th World Health Assembly (WHA) in 2023, which unanimously adopted the resolution to address micronutrient deficiencies through safe, effective food fortification to prevent congenital disorders such as spina bifida and anencephaly, the first neurosurgery-led resolution since the founding of the World Health Organization. The WHA included other resolutions and side events by the G4 Alliance and other organizations relevant to neurosurgery. An opportunity exists for neurosurgeons to harness the momentum from this resolution to promote initiatives to prevent neurosurgical disease or expand access to neurosurgical care.

Surgical Treatment Results of Adult Tethered Spinal Cord Syndrome.

AIM: To present symptoms and surgical results of patients operated on with the diagnosis of tethered cord syndrome (TCS) in adulthood. MATERIAL AND METHODS: In this retrospective study, 20 patients older than 18 years were evaluated. There were 17 female and 3 male patients. Patient demographics, clinical and surgical results were evaluated. RESULTS: The mean age was 29.9 years and the mean follow-up period was 30 months. Of the 20 patients with low back and leg pain, 16 had relief. Two were partially benefited and 2 were unchanged. In nine patients, carrying heavy loads, excessive exercise, childbirth, and walking too long before the onset of symptoms were detected. Complaint of urinary incontinance was improved only in one patient. Three of them continued with frequent urination. There was no change in two of them. There was no improvement in sensory dysfunction and sphincter dysfunction. CONCLUSION: In patients diagnosed with TCS in adulthood, symptoms may begin with physical activity, and clinical recovery is better when early surgery is performed.

Management of split cord malformation and tethered cord syndrome: Experience of a main referral center in Uzbekistan.

BACKGROUND: Split cord malformation and tethered cord syndrome are challenging pathologies in the pediatric population. During 2016-2022, 56 cases of split cord malformation (SCM) and tethered cord syndrome were treated at the Republican Specialized Scientific Medical Practical Center of Neurosurgery (RSSMPCN) of Uzbekistan. This article aims to provide a retrospective analysis of the clinical presentation, radiological findings, and surgical outcomes of patients with split cord malformation and tethered cord syndrome. METHODS: The retrospective study was conducted for 56 pediatric patients with split cord malformation and tethered cord syndrome during the abovementioned six-year period. All patients underwent MR imaging with computed tomography, followed by surgery with intraoperative neurophysiological monitoring. Each patient underwent follow-up examinations at 3 and 6 months postoperatively and yearly thereafter. RESULTS: The mean patient age was 5.7 years (10 months to 15 years), and the male-to-female ratio was 1:2.2. Encouragingly, 44 (78.6 %) of the 56 patients showed improved neurological status postoperatively. Even in the cases where spur resection procedures were performed, there was partial neurological improvement, demonstrating the overall positive outcomes of the surgeries. Importantly, none of the 56 patients had neurological deteriorations in the postoperative period CONCLUSIONS: Split cord malformation is a rare but challenging pathology of childhood. The presentation is primarily characterized by movement, sensory or bowel disorders, and back and leg pain. This underscores the importance of early recognition and intervention when neurological symptoms are evident. Surgical intervention, as demonstrated in our study, is both appropriate and efficient in improving the neurological status of the patients.

[Clinical Evaluation of Dural (Spinal) Membrane Repair Materials].

Objective: To select high-quality and cost-effective dural (spinal) membrane repair materials, in order to reduce the cost of consumables procurement, save medical insurance funds, and optimize hospital operation and management. Methods: Taking the BS06B disease group (spinal cord and spinal canal surgery without extremely severe or severe complications and comorbidities, mainly diagnosed as congenital tethered cord syndrome) as an example, a retrospective analysis was conducted on the relevant data of surgical treatment for congenital tethered cord syndrome conducted in our hospital from January 2021 to June 2023. Safety and efficacy indicators in clinical application (incidence of postoperative epidural hemorrhage, incidence of postoperative purulent cerebrospinal meningitis, incidence of cerebrospinal fluid leakage, surgical duration, and postoperative hospital stay) were compared. Results: There was no difference in safety and effectiveness between different brands of dura mater repair materials. Conclusion: For the repair of small incisions in dura mater surgery, high-quality and cost-effective dura mater repair materials can be selected to reduce hospital costs and control expenses for the disease group.

Walking recovery after tethered cord release.

After myelomeningocele (MMC) repair, a secondary tethered spinal cord occurs in almost all patients. The tethered spinal cord may result in progressive neurological deterioration and walking disability. This retrospective cohort study aimed to highlight the walking recovery one year after tethered cord release and its relation to the preoperative conus level. We reviewed the medical records at our university hospital from January 2014 to December 2022. The patients who underwent spinal cord untethering following lumbosacral MMC repair were included. We assessed the walking recovery one year after cord release using the modified Benzel scale. Thirty-seven patients met our selection criteria. There were 19 girls (51.4%) and 18 boys (48.6%). Their mean age at presentation was 8.6 years. The preoperative conus vertebral levels ranged between L4 and S3. One year after spinal cord release, 37.8% of the patients regained their walking ability. All the patients whose preoperative conus level was at S2 or S3 regained their walking ability. In contrast, all the patients with preoperative conus levels at L4 or L5 didn't regain their ability to walk. One-third (33.3%) of patients whose conus was at the S1 level regained their walking ability one year after cord release. One year after tethered cord release, 37.8% of the patients regained their walking ability. We found that the walking recovery was statistically associated with the preoperative conus level. A multicenter prospective study is required to support the results of this study.

Tethered cord syndrome from pediatric and adult perspectives: a comprehensive systematic review of 6135 cases.

OBJECTIVE: This study aimed to investigate the differences in clinical features, diagnostic examination, treatment, and pathological results between adult-onset and pediatric-onset tethered cord syndrome (TCS). METHODS: The authors searched the PubMed, Embase, and Cochrane Library databases through January 2023 for reports on TCS, extracting information on clinical features, imaging data, treatment modalities, prognosis, and pathological research results. A total of 6135 cases from 246 articles were included in the analysis. This review was conducted in accordance with the 2020 PRISMA guidelines and registered on PROSPERO. RESULTS: The most common adult clinical manifestations were pain, urinary symptoms, and numbness; in children, they were urinary symptoms, skin lesions, bowel symptoms, and unspecific motor deficits. Surgical treatment was the primary approach for both adults and children, with a higher clinical improvement rate observed in adults. However, adults also had a higher rate of surgical complications than children. TCS pathological studies have not yet identified the differences between adults and children, and the pathogenesis of adult-onset TCS requires further investigation. CONCLUSIONS: Adult-onset and pediatric-onset TCS exhibit certain differences in clinical characteristics, diagnostic examinations, and treatments. However, significant differences have not been found in current pathological studies between adults and children. Systematic review registration no.: CRD42023479450 (www.crd.york.ac.uk/prospero).

Application of neurophysiological monitoring during tethered cord release in children.

OBJECTIVE: The objective of this study was to explore the effect of intraoperative neurophysiological monitoring (IONM) on tethered spinal cord release in children. METHODS: The clinical data of 454 children with tethered cord syndrome who underwent surgery for tethered cord release were retrospectively analyzed. The children were divided into two groups: the non-IONM group and the IONM group. SPSS 26.0 software was used for statistical analysis. The evaluation indices included the effective rate and incidence of new neurological dysfunction. RESULTS: The short-term results showed that the effective rate of the non-IONM group was 14.8%, while that of the IONM group was 15.2%. Additionally, the incidence of new neurological dysfunction was 7.8% in the non-IONM group and 5.6% in the IONM group. However, there was no significant difference between the two groups (P > 0.05). The medium- to long-term follow-up had significant difference (P < 0.05), the response rate was 32.1% in the IONM group and 23.7% in the non-IONM group, and deterioration rates regarding neurological dysfunction were 3.3% in the IONM group and 8.5% in the non-IONM group. CONCLUSION: This study revealed that the use of IONM does not significantly improve the short-term treatment effect of patients undergoing surgery for tethered cord release or reduce the short-term incidence of postoperative new neurological dysfunction. However, the medium- to long-term prognoses of patients in the IONM group were better than those of patients in the non-IONM group.

Spinal neurenteric cysts: experience with 9 cases via an anterior cervical approach.

OBJECTIVE: Intraspinal cysts are uncommon, and the success rate of complete resection is still low for spinal neurenteric cysts (NCs). The aim of this study was to evaluate the efficacies of an anterior microscopic surgical approach in the treatment of ventral and ventrolateral subaxial cervical NCs (SCNCs). METHODS: Between 2019 and 2022, 9 patients with NCs of the subaxial spine underwent an anterior microsurgical approach. Their clinical presentations, radiological features, operative findings, and follow-up data were retrospectively reviewed and analyzed. RESULTS: All spinal cysts were intradural and extramedullary in origin. Five patients were first-time cases while 4 patients with recurrence underwent revision surgery. The most common clinical manifestation was pain (77.78%). One patient was found to have a concomitant disorder of Klippel-Feil syndrome. Microscopically confirmed gross-total resection was achieved in 8 patients (88.89%) based on clinical comparisons between pre- and postoperative MRI and intraoperative video. One patient had symptom recurrence 1 year after subtotal resection, while there was no evidence of recurrence during follow-up for the other patients. Dense adhesions within the spinal cord were observed in 8 patients (88.89%) intraoperatively. Most importantly, the surgical outcome was significantly improved in all patients, and the mean (± SE) Japanese Orthopaedic Association score increased from 11.33 ± 0.91 preoperatively to 16.22 ± 0.32 postoperatively (p = 0.008). CONCLUSIONS: An anterior surgical approach was proven to be both safe and effective in treating the ventral or ventrolateral SCNCs. The authors believe that an anterior microsurgical approach should be considered as a useful approach especially in patients with ventral recurrent SCNCs. Its clinical efficacy compared with a posterior approach in ventral spinal cyst may be better as most of the neurenteric cysts are ventrally or ventrolaterally located.

Diagnosis and Management of Tethered Cord Syndrome.

Tethered cord syndrome is a condition in which the spinal cord is tethered by pathological structures such as a tight filum terminale, intradural lipomas with or without a connecting extradural component, intradural fibrous adhesions, diastematomyelia, and neural placode adhesions following closure of a myelomeningocele.It usually occurs in childhood and adolescence as the spine grows in length, but it can also develop in adulthood. Symptoms of tethered cord syndrome are slowly progressive and varied. Incorrect diagnosis and inappropriate treatment may be provided if the physician lacks knowledge and understanding of this disease.This chapter aims to describe the pathophysiology, syndromes, diagnostic imaging, surgical treatment, and prognosis of tethered cord syndrome to enhance the understanding of this condition.

Quality of Life of Children Treated for Split Cord Malformation.

OBJECTIVE: Split cord malformation (SCM), associated with neurologic deficits, necessitates surgical intervention for spinal cord detethering. Limited evidence exists regarding its impact on children's quality of life. Our study aims to evaluate the postoperative quality of life in children treated for SCM. METHODS: This retrospective cohort study examined records of patients with SCM operated on between July 1, 2012, and July 31, 2022, at a single center. Data, including Health Utility Index-3 (HUI-3) scores provided by guardians, was collected to assess quality of life. Clinical and neurologic outcomes were also analyzed. RESULTS: Twenty-five patients, predominantly female (68%), with a median age of 7 years, were included. Most presented with normal motor function (76%). The most common anatomic level of SCM was lumbar (12; 48%) followed by lumbosacral (5; 20%). A bony spur from the lamina was the most common cause of splitting the cord (64%). Over a median follow-up of 3.3 years, 64% of patients showed neurologic stability, 16% showed neurologic improvement, and 4% experienced deterioration. The mean HUI-3 score for 21 children was 0.93 ± 0.24. CONCLUSIONS: Surgical management of SCM showed favorable neurologic outcomes and a positive long-term quality of life, as shown by HUI-3 scores. Our findings emphasize the efficacy of surgical intervention in improving the lives of children with this condition.

lVentral tethering-is the prognosis worse than in dorsal tethering in the dysraphic spine?

OBJECTIVE: To compare cases of dysraphism with ventral tethering of cord with those with dorsal tethering and to find out any differences in the outcome of surgery in them. METHODS: We collected the data of 188 consecutively operated tethered cord patients at our institute in the past 7 years and divided them into ventral tethering and dorsal tethering groups. Those that we felt had both dorsal and ventral tethering were excluded. Their preoperative clinical, radiological, and baseline neurophysiological parameters as well as postoperative clinical and radiological parameters were analyzed in a retrospective study. RESULTS: Among the 188 tethered cord patients, 52 (28%) had ventral tethering and 136 (72%) had posterior tethering. Preoperative neurodeficit and cord signal changes as well as absent baseline MEP (of any one muscle) were significantly more associated with ventral tethered cord than the dorsal tethered cord. The neurological deterioration after surgery occurred significantly in the ventral tethered cord group than in the dorsal tethered cord group. Also, the postoperative MRI had more incomplete detethering cases in the ventral group than in the dorsal tethered cord group. CONCLUSION: Ventral tethered cord is more likely to present with preoperatively neurological deficits. It should be carefully identified in the preoperative MRI, so that the intraoperative difficulties in complete detethering and postoperative deterioration can be anticipated.

The impact of a biocellulose-based repair of fetal open spina bifida on the need to untether the cord: is it time to unify techniques for prenatal repair?

OBJECTIVE: To report the need for cord untethering after prenatal repair of open spina bifida using a unique biocellulose-based technique performed at a later gestational age. METHODS: An observational cohort study was conducted to determine the incidence of tethered cord syndrome. Between May 2013 and May 2022, we performed 172 procedures using the percutaneous fetoscopic approach in fetuses at 26-28 weeks of gestation. After placode dissection, a biocellulose patch was placed to cover the placode, a myofascial flap (when possible) was dissected, and the skin was closed. Owing to death or loss to follow-up, 23 cases were excluded. Cord tethering syndrome was defined as symptoms of medullary stretching, and the infants were evaluated and operated on by local neurosurgeons after an magnetic resonance imaging examination. Infants over 30-month had ambulation and neurodevelopment evaluations (PEDI scale). RESULTS: Among 172 cases operated at a median gestational age of 26.7 weeks and delivered at 33.2 weeks, 149 cases were available for postnatal follow-up, and cord untethering was needed in 4.4% of cases (6/136; excluding 13 cases younger than 12 months). Cerebrospinal fluid diversion and bladder catheterization were needed in 38% and 36% of cases, respectively. Of the 78 cases evaluated at 30 months, 49% were ambulating independently, and 94% had normal social function. CONCLUSION: The biocellulose-based technique was associated with a low rate of cord tethering, wich may be attributed to the lack of the duramater suture during prenatal repair, the formation of a neoduramater and/or later gestational age of surgery.

Patterns and short term neurosurgical treatment outcomes of neonates with neural tube defects admitted to Felege Hiwot Specialized Hospital, Bahir Dar, Ethiopia.

BACKGROUND: Neural tube defects (NTDs) account for the largest proportion of congenital anomalies of the central nervous system and result from failure of the neural tube to close spontaneously between the 3rd and 4th weeks of in utero development. Prognosis and treatment outcome depends on the nature and the pattern of the defect. The nature of treatment outcomes and its pattern associated with grave prognosis is not well known in the study area. OBJECTIVE: The aim of study was to determine the patterns and short term neurosurgical management outcomes of newborns with neural tube defects admitted at Felege Hiwot Specialized Hospital. METHODS: Institutional based retrospective cross-sectional study among neonates, who were admitted at Felege Hiwot Specialized Hospital with neural tube defects from January 1st to December, 30th, 2018 was conducted. All Charts of Neonates with confirmed diagnosis of neural tube defects were included as part of the study. Trained data collectors (medical interns) supervised by trained supervisors (general practitioners) collected the data using a pretested data extraction format. Data were coded, entered and analyzed using SPSS version 23 software. Frequency and cross tabulations were used to summarize descriptive statistics of data, and tables and graphs were used for data presentation. RESULT: About 109 patients had complete documentation and imaging confirmed neural tube defects. Myelomeningocele was the commonest pattern 70 (64.2%). Thoracolumbar spine was the commonest site of presentation 49(45%). The most common associated impairment was hydrocephalus 37(33.9%). Forty-five (41.1%) had multiple complications. The mortality rate was 7.3%, 44% were discharged with sequalae and 36.7% were discharged without impairment. The significant causes of death were infection 66.7% and Chiari crisis 33.3%. CONCLUSION: Myelomeningocele was the most frequent clinical pattern of neural tube defect and thoracolumbar spine was the commonest site. Isolated neural tube defect was the commonest finding. There were multiple complications after surgery accompanied with meningitis and hydrocephalus. The mortality rate among neonates with neural tube defects was considerably high. The commonest causes of death were infection and Chiari crisis.

Disparities in Indications and Outcomes Reporting for Spinal Column Shortening for Tethered Cord Syndrome: The Need for a Standardized Approach.

STUDY DESIGN: Systematic review. OBJECTIVE: To identify commonly reported indications and outcomes in spinal column shortening (SCS) procedures. BACKGROUND: SCS is a surgical procedure used in patients with tethered cord syndrome-characterized by abnormal attachment of neural components to surrounding tissues-to shorten the vertebral column, release tension on the spinal cord/neural elements, and alleviate associated symptoms. PATIENTS AND METHODS: PubMed and EMBASE searches captured SCS literature published between 1950 and 2023. Prospective/retrospective cohort studies and case series were included without age limit or required follow-up period. Review articles without new patient presentations, meta-analyses, systematic reviews, conference abstracts, and letters were excluded. Studies included adult and pediatric patients. RESULTS: The 29 identified studies represented 278 patients (aged 5-76 yr). In 24.1% of studies, patients underwent primary tethered cord syndrome intervention through SCS. In 41.4% of studies, patients underwent SCS after failed previous primary detethering (24.1% of studies were mixed and 10.3% were unspecified). The most commonly reported nongenitourinary/bowel surgical indications were back pain (55.2%), lower-extremity pain (48.3%), lower-extremity weakness (48.3%), lower-extremity numbness (34.5%), and lower-extremity motor dysfunction (34.5%). Genitourinary/bowel symptoms were most often described as nonspecific bladder dysfunction (58.6%), bladder incontinence (34.5%), and bowel dysfunction (31.0%). After SCS, nongenitourinary/bowel outcomes included lower-extremity pain (44.8%), back pain (31.0%), and lower-extremity sensory and motor function (both 31.0%). Bladder dysfunction (79.3%), bowel dysfunction (34.5%), and bladder incontinence (13.8%) were commonly reported genitourinary/bowel outcomes. In total, 40 presenting surgical indication categories and 33 unique outcome measures were reported across studies. Seventeen of the 278 patients (6.1%) experienced a complication. CONCLUSION: The SCS surgical literature displays variability in operative indications and postoperative outcomes. The lack of common reporting mechanisms impedes higher-level analysis. A standardized outcomes measurement tool, encompassing both patient-reported outcome measures and objective metrics, is necessary. LEVEL OF EVIDENCE: Level IV.

Aberrant Dorsal Nerve Root as a Concomitant Cause of Spinal Cord Tethering Associated with a Dorsal Type Lipomyelomeningocele in a Child With Caudal Agenesis.

ABSTRACT: Tethered cord syndrome is a neurological disorder closely associated with congenital spinal dysraphism. Aberrant dorsal nerve roots may be one of the possible and relatively rare tethering pathologies, especially in the complex form of occult spinal dysraphism such as caudal regression syndrome or split cord malformation. We report an illustrative case of caudal regression syndrome with spinal cord tethering due to a combination of a contiguous bundle of an aberrant dorsal nerve root, and a dorsal-type lipomyelomeningocele, with a thickened filum terminale treated with microneurosurgical untethering.

Clinical criteria for filum terminale resection in occult tethered cord syndrome.

OBJECTIVE: Tethered cord syndrome (TCS) comprises three symptom categories: back/leg pain, bowel/bladder, and neurological complaints. MRI typically reveals a low-lying conus medullaris, filum terminale (FT) pathology, or lumbosacral abnormalities. FT resection is established in TCS but not in radiologically occult TCS (OTCS). This study aims to identify patients with OTCS who are likely to benefit from FT resection. METHODS: The authors recruited 149 patients with OTCS (31 pediatric, 118 adult) treated with FT resection-including only cases with progressive TCS, negative spine MRI, and no concurrent neurological/urological conditions. A comprehensive questionnaire collected patient self-reported symptoms and clinical findings at the preoperative and at 3- and 12-month follow-up examinations. Based on questionnaire data, the authors extracted a 15-item symptoms and findings scale to represent the three TCS symptom categories, assigning 1 point for each item present. RESULTS: OTCS presents without radicular/segmental sensorimotor findings, but with leg/back pain and conus dysfunction, in addition to leg fatigue and spasticity; the latter indicating an upper motoneuron pathology. The 15-item scale showed clinical improvement in 89% of patients at the 3-month follow-up and 68% at the 12-month follow-up. Multivariate analysis of the scale revealed that it accurately predicts outcome of FT resection in 82% of cases. Patients with a preoperative score exceeding 6 points are most likely to benefit from surgery. CONCLUSIONS: By applying the study's inclusion criteria and incorporating the novel 15-item scale, surgeons can effectively select candidates for FT resection in patients with OTCS. The observed outcomes in these selected patients are comparable to those achieved in degenerative spine surgery.

Preliminary Experience with 3-Dimensional-Exoscopic Untethering of a Type II Diastematomyelia: Technical Note and Review of the Literature.

OBJECTIVE: To describe the use of a high-definition 3-dimensional (3D) exoscope (VITOM 3D exoscope; KARL STORZ GmbH) for the neurosurgical treatment of a rare pediatric disease, type II diastematomyelia with associated tethered cord. METHODS: A 13-year-old girl who presented with diastematomyelia type II with a tethered cord was surgically treated with the aid of a high-definition 3D exoscope, with a third operator moving and pivoting its arm. Intraoperative monitoring and mapping were arranged. The surgery required a bilateral access to address both the split cord malformation and the tethering of the filum terminale. The filum terminale was identified and cut, and the connective fibrovascular tissue separating the 2 medullary halves was unraveled. These steps were performed with no changes of intraoperative monitoring. Pertinent literature was addressed carefully. RESULTS: The surgery was successful, and the patient was discharged home on the eleventh postoperative day without any complications. The 3-month postoperative magnetic resonance imaging scan demonstrated regular surgical outcomes; no dynamic motor disturbances were reported. To our knowledge, this is the first spinal congenital malformation treated with the use of a 3D exoscope. CONCLUSIONS: The use of 3D exoscope is advancing in spinal surgery, as it provides magnification, stereopsis, lighting, and definition comparable with the operating microscope; the addition of a third operator simplified the operations of moving around the arm, releasing these burdens for the surgeons. Our preliminary experience proved that the use of a 3D exoscope is feasible and safe for the surgical management of a type II diastematomyelia with tethered cord.

Use of a machine learning algorithm with a focus on spinopelvic parameters to predict development of symptomatic tethered cord after initial untethering surgery.

OBJECTIVE: Among patients with a history of prior lipomyelomeningocele repair, an association between increased lumbosacral angle (LSA) and cord retethering has been described. The authors sought to build a predictive algorithm to determine which complex tethered cord patients will develop the symptoms of spinal cord retethering after initial surgical repair with a focus on spinopelvic parameters. METHODS: An electronic medical record database was reviewed to identify patients with complex tethered cord (e.g., lipomyelomeningocele, lipomyeloschisis, myelocystocele) who underwent detethering before 12 months of age between January 1, 2008, and June 30, 2022. Descriptive statistics were used to characterize the patient population. The Caret package in R was used to develop a machine learning model that predicted symptom development by using spinopelvic parameters. RESULTS: A total of 72 patients were identified (28/72 [38.9%] were male). The most commonly observed dysraphism was lipomyelomeningocele (41/72 [56.9%]). The mean ± SD age at index MRI was 2.1 ± 2.2 months, at which time 87.5% of patients (63/72) were asymptomatic. The mean ± SD lumbar lordosis at the time of index MRI was 23.8° ± 11.1°, LSA was 36.5° ± 12.3°, sacral inclination was 30.4° ± 11.3°, and sacral slope was 23.0° ± 10.5°. Overall, 39.6% (25/63) of previously asymptomatic patients developed new symptoms during the mean ± SD follow-up period of 44.9 ± 47.2 months. In the recursive partitioning model, patients whose LSA increased at a rate ≥ 5.84°/year remained asymptomatic, whereas those with slower rates of LSA change experienced neurological decline (sensitivity 77.5%, specificity 84.9%, positive predictive value 88.9%, and negative predictive value 70.9%). CONCLUSIONS: This is the first study to build a machine learning algorithm to predict symptom development of spinal cord retethering after initial surgical repair. The authors found that, after initial surgery, patients who demonstrate a slower rate of LSA change per year may be at risk of developing neurological symptoms.