The characteristic and biomarker value of transcranial sonography in cerebellar ataxia.

OBJECTIVE: Transcranial sonography (TCS) is a noninvasive neuroimaging technique, visualizing deep brain structures and the ventricular system. Although widely employed in diagnosing various movement disorders, such as Parkinson's disease and dystonia, by detecting disease-specific abnormalities, the specific characteristics of the TCS in cerebellar ataxia remain inconclusive. We aimed to assess the potential value of TCS in patients with cerebellar ataxias for disease diagnosis and severity assessment. METHODS: TCS on patients with genetic and acquired cerebellar ataxia, including 94 with spinocerebellar ataxias (SCAs) containing 10 asymptomatic carriers, 95 with cerebellar subtype of multiple system atrophy (MSA-C), and 100 healthy controls (HC), was conducted. Assessments included third ventricle width, substantia nigra (SN) and lentiform nucleus (LN) echogenicity, along with comprehensive clinical evaluations and genetic testing. RESULTS: The study revealed significant TCS abnormalities in patients with cerebellar ataxia, such as enlarged third ventricle widths and elevated rates of hyperechogenic SN and LN. TCS showed high accuracy in distinguishing patients with SCA or MSA-C from HC, with an AUC of 0.870 and 0.931, respectively. TCS abnormalities aided in identifying asymptomatic SCA carriers, effectively differentiating them from HC, with an AUC of 0.725. Furthermore, third ventricle width was significantly correlated with SARA and ICARS scores in patients with SCA3 and SCOPA-AUT scores in patients with MSA-C. The SN area and SARA or ICARS scores in patients with SCA3 were also positively correlated. INTERPRETATION: Our findings illustrate remarkable TCS abnormalities in patients with cerebellar ataxia, serving as potential biomarkers for clinical diagnosis and progression assessment.

Third Ventricular Colloid Cyst, New Surgical Classification.

BACKGROUND: This research discusses colloid cyst surgical concerns, with an emphasis on the value of a novel surgical classification based on anatomical sites. In the study, 59 patients who underwent surgical intervention between 2009 and 2022 and were diagnosed with colloid cysts via computed tomography scan and magnetic resonance imaging participated. METHODS: There were more male cases than female ones (57.6%). The majority of patients presented with headache (79%), followed by abnormal gait (12%), visual blurring (5%), and seizures (4%). RESULTS: In this study, we present a new surgical classification based on anatomical locations, distinguishing 4 types: open Monro type (50.84%), closed Monro type (23.72%), retroforaminal type (13.55%), and interforniceal type (11.86%). CONCLUSIONS: In summary, the surgical classification that has been suggested provides significant insights into the varied anatomical sites where colloid cysts might be found. Microneurosurgeons significantly need to be oriented about the possible sites of colloid cysts through this classification to achieve complete and curative resection and reduce the likelihood of recurrence.

Combined blood Neurofilament light chain and third ventricle width to differentiate Progressive Supranuclear Palsy from Parkinson's Disease: A machine learning study.

INTRODUCTION: Differentiating Progressive Supranuclear Palsy (PSP) from Parkinson's Disease (PD) may be clinically challenging. In this study, we explored the performance of machine learning models based on MR imaging and blood molecular biomarkers in distinguishing between these two neurodegenerative diseases. METHODS: Twenty-eight PSP patients, 46 PD patients and 60 control subjects (HC) were consecutively enrolled in the study. Serum concentration of neurofilament light chain protein (Nf-L) was assessed by single molecule array (SIMOA), while an automatic segmentation algorithm was employed for T1-weighted measurements of third ventricle width/intracranial diameter ratio (3rdV/ID). Machine learning (ML) models with Logistic Regression (LR), Random Forest (RF), and XGBoost algorithms based on 3rdV/ID and serum Nf-L levels were tested in distinguishing among PSP, PD and HC. RESULTS: PSP patients showed higher serum Nf-L levels and larger 3rdV/ID ratio in comparison with both PD and HC groups (p < 0.005). All ML algorithms (LR, RF and XGBoost) showed that the combination of MRI and blood biomarkers had excellent classification performances in differentiating PSP from PD (AUC ≥0.92), outperforming each biomarker used alone (AUC: 0.85-0.90). Among the different algorithms, XGBoost was slightly more powerful than LR and RF in distinguishing PSP from PD patients, reaching AUC of 0.94 ± 0.04. CONCLUSION: Our findings highlight the usefulness of combining blood and simple linear MRI biomarkers to accurately distinguish between PSP and PD patients. This multimodal approach may play a pivotal role in patient management and clinical decision-making, paving the way for more effective and timely interventions in these neurodegenerative diseases.

Topographical distribution and prevalence of basal duct-like recess sign in a cohort of Papillary Craniopharyngioma-novel findings and implications.

PURPOSE: Basal duct-like recess (DR) sign serves as a specific marker of papillary craniopharyngiomas (PCPs) of the strictly third-ventricular (3 V) topography. Origins of this sign are poorly understood with limited validation in external cohorts. METHODS: In this retrospective study, MRIs of pathologically proven PCPs were reviewed and evaluated for tumor topography, DR sign prevalence, and morphological subtypes. RESULTS: Twenty-three cases with 24 MRIs satisfied our inclusion criteria. Median age was 44.5 years with a predominant male distribution (M/F ratio 4.7:1). Overall, strictly 3 V was the commonest tumor topography (8/24, 33.3%), and tumors were most commonly solid-cystic (10/24, 41.7%). The prevalence of DR sign was 21.7% (5/23 cases), all with strictly 3 V topography and with a predominantly solid consistency. The sensitivity, specificity and positive and negative predictive value of the DR sign for strict 3 V topography was 62.5%, 100%, 100% and 84.2% respectively. New pertinent findings associated with the DR sign were observed in our cohort. This included development of the cleft-like variant of DR sign after a 9-year follow-up initially absent at baseline imaging. Additionally, cystic dilatation of the basal tumor cleft at the pituitary stalk-tumor junction and presence of a vascular structure overlapping the DR sign were noted. Relevant mechanisms, hypotheses, and implications were explored. CONCLUSION: We confirm the DR sign as a highly specific marker of the strictly 3 V topography in PCPs. While embryological and molecular factors remain pertinent in understanding origins of the DR sign, non-embryological mechanisms may play a role in development of the cleft-like variant.

Intraventricular Tumors: Surgical Considerations in Lateral and Third Ventricular Tumors.

Management of lateral and third ventricular tumors has been a challenge for neurosurgeons. Advances in imaging and pathology have helped in a better understanding of the treatment options. Technical refinement of microsurgical technique and addition of endoscopy has enabled more radical excision of tumors, when indicated, and added more safety.A proper understanding of the pathology at various ages and treatment options is continuously evolving. Many pediatric tumors are amenable to conservative surgical methods with effective complementary treatments. However, radical surgery is required in many adults as the main treatment and for many benign tumors. Various intraventricular lesions encountered and their surgical management is reviewed here for their efficacy, safety, and outcome, encompassing changes in our practice over the last 20 years.

Neuroendoscopic access to the third ventricle in patients with narrow foramen of monro without stenosis/obstruction: role of foraminoplasty.

OBJECT: One of the critical steps for the success of intraventricular neuroendoscopic procedures is the entry into the third ventricle and passage of the endoscopy system through the foramen of Monro (FM). A diameter larger than that of the instrument used is considered a prerequisite for safely performing the technique, as damage to this structure can lead to alterations in the fornix and vascular structures. When the foramen diameter is narrow and there is no obstruction/stenosis, the role of foraminoplasty in reducing the risk of complications has not been adequately assessed in the literature. METHODS: A review of endoscopic procedures conducted at our center since 2018 was undertaken. Cases in which preoperative imaging indicated a FM diameter < 6 mm and foraminoplasty technique was applied were examined to determine the technical and functional success of the procedure. The technical success was determined by completing the neuroendoscopic procedure with the absence of macroscopic lesions in the various structures comprising the foramen and without complications in the follow-up imaging tests. Functional success was defined as the absence of cognitive/memory alterations during the 3-month postoperative follow-up. Additionally, a review of the various forms of foraminoplasty described in the literature is conducted. RESULTS: In our cohort, six patients were identified with a preoperative FM diameter < 6 mm without obstruction or stenosis. Foraminoplasty was planned for these cases to facilitate various intraventricular neuroendoscopic procedures. In all instances, the technique was successfully performed without causing macroscopic damage to the structures comprising the foramen. Follow-up visits included various cognitive tests to assess potential sequelae related to microscopic damage to the fornix. None of the patients exhibited anomalies. CONCLUSION: Foraminoplasty in patients with a narrow FM without signs of stenosis/obstruction is a useful technique to reduce the risk of complications during the passage of the endoscopy system through this structure, enabling the safe performance of neuroendoscopic procedures.

Ultrasound-guided initial diagnosis and follow-up of pediatric idiopathic intracranial hypertension.

BACKGROUND: Idiopathic intracranial hypertension in children often presents with non-specific symptoms found in conditions such as hydrocephalus. For definite diagnosis, invasive intracranial pressure measurement is usually required. Ultrasound (US) of the optic nerve sheath diameter provides a non-invasive method to assess intracranial pressure. Transtemporal US allows imaging of the third ventricle and thus assessment for hydrocephalus. OBJECTIVE: To investigate whether the combination of US optic nerve sheath and third ventricle diameter can be used as a screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure and exclude hydrocephalus as an underlying pathology. Further, to analyze whether both parameters can be used to monitor treatment outcome. MATERIALS AND METHODS: We prospectively included 36 children with idiopathic intracranial hypertension and 32 controls. Using a 12-Mhz linear transducer and a 1-4-Mhz phased-array transducer, respectively, optic nerve sheath and third ventricle diameters were determined initially and during the course of treatment. RESULTS: In patients, the mean optic nerve sheath diameter was significantly larger (6.45±0.65 mm, controls: 4.96±0.32 mm) and the mean third ventricle diameter (1.69±0.65 mm, controls: 2.99±1.31 mm) was significantly smaller compared to the control group, P<0.001. Optimal cut-off values were 5.55 mm for the optic nerve sheath and 1.83 mm for the third ventricle diameter. CONCLUSIONS: The combined use of US optic nerve sheath and third ventricle diameter is an ideal non-invasive screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure while ruling out hydrocephalus. Treatment can effectively be monitored by repeated US, which also reliably indicates relapse.

Fully Endoscopic Minimally Invasive Trans-Eyebrow Supraorbital Translaminar Approach to Third Ventricle Craniopharyngiomas: Technical Nuances and Stepwise Illustrative Description.

BACKGROUND: Traditional microsurgical approaches for addressing intraventricular craniopharyngioma provide limited access to the retrochiasmatic area and tumors with significant lateral or rostrocaudal extensions. Extended endoscopic endonasal approaches can effectively overcome many of limitations, yet they require a favorable working angle between the optic chiasm and pituitary gland, as well as the involvement of the third ventricle floor by the tumor. METHODS: Herein, the authors describe the surgical nuances of a keyhole technique for resecting third ventricle craniopharyngiomas via a fully endoscopic minimally invasive trans-eyebrow supraorbital translaminar approach (ESOTLA). A case description detailing the key surgical steps and application of the approach is provided, along with a series of cadaveric photographs to highlight the relevant anatomy and step-by-step dissection process. RESULTS: The patient is a 44-year-old man who presented with polyuria, low urine specific gravity, and panhypopituitarism. Brain magnetic resonance imaging revealed a solid-cystic heterogeneous-enhanced retrochiasmatic mass within the third ventricle, consistent with craniopharyngioma. A 1-stage ESOTLA was indicated based on the narrow pituitary-chiasm angle and the high functional status of the patient. Near-total resection was achieved, and no new postoperative neurologic or endocrine change was observed. Targeted therapy was implemented based on the histologic result, and the most recent surveillance magnetic resonance imaging showed no evidence of the residual tumor. CONCLUSIONS: By combining a keyhole approach with variable-angle endoscopic visualization through a smaller bony and soft tissue exposure, ESOTLA can provide enhanced illumination within the third ventricle, potentially addressing cosmetic concerns and limited exposure area/angle of freedom associated with its conventional microsurgical counterpart.

[Microsurgical ventriculostomy of the third ventricle with access through a burrhole in the treatment of midly located deep-seated brain tumors]. / Mikrokhirurgicheskaya ventrikulostomiya III zheludochka s dostupom cherez frezevoe otverstie v lechenii sredinno raspolozhennykh glubinnykh opukholei golovnogo mozga.

BACKGROUND: Currently, endoscopic third ventriculostomy and simultaneous biopsy of deep midline brain tumors are a generally accepted option in neurooncology. Nevertheless, effectiveness of this surgery and diagnostic accuracy of biopsy are not without drawbacks. An alternative to endoscopic surgery may be simultaneous microsurgical third ventriculostomy and biopsy of deep midline tumors. OBJECTIVE: To evaluate effectiveness and safety of burr hole microsurgical third ventriculostomy in the treatment of deep midline brain tumors. MATERIAL AND METHODS: We used transcortical (25 cases) and transcallosal (8 cases) approaches for microsurgical third ventriculostomy. RESULTS: Initially scheduled biopsy was performed in 19 cases, partial resection in 6 cases, subtotal resection in 4 cases and total resection in 4 cases. All patients underwent microsurgical third ventriculostomy. In 12 cases, stenting of stoma was performed in addition to ventriculostomy. Biopsy was informative in all cases. Postoperative follow-up period ranged from 3 to 44 months (mean 29 months). There was no postoperative hydrocephalus and need for shunting procedure. CONCLUSION: Burr hole microsurgery may be an alternative to endoscopic surgery for the treatment of pineal, periaqueductal and third ventricular tumors.

Combined Predictive Model for Endoscopic Third Ventriculostomy Success in Adults and Children.

BACKGROUND: The selection of patients in whom endoscopic third ventriculostomy (ETV) can be effective remains poorly defined. The ETV success score (ETVSS) and the presence of bowing of the third ventricle have been identified as independent factors for predicting success, each with limitations. The objective of this study is to elaborate a combined predictive model to predict ETV success in a mixed cohort of patients. METHODS: Demographic, intraoperative, postoperative, and radiologic variables were analyzed in all ventriculostomies performed consecutively at a single institution from December 2004 to December 2022. Qualitative and quantitative measurements of preoperative, immediate, and late postoperative magnetic resonance imaging were conducted. Univariate analysis and logistic regression models were performed. RESULTS: 118 ETVs were performed in the selected period. Of these procedures, 106 met the inclusion criteria. The overall success rate was 71.7%, with a median follow-up of 3.64 years (interquartile range, 1.06-5.62). The median age was 36.1 years (interquartile range, 11.7-53.5). 35.84% were children (median, 7.81 years). Among the 80 patients with third ventricle bowing, the success rate was 88.8% (P < 0.001). Larger third ventricle dimensions on preoperative mid-sagittal magnetic resonance imaging were associated with increased ETV success. The model with the best receiver operating characteristic curves, with an area under the curve of 0.918 (95% confidence interval, 0.856-0.979) includes sex, ETVSS, presence of complications, and third ventricle bowing. CONCLUSIONS: The presence of bowing of the third ventricle is strongly associated with a higher ETV success rate. However, a combined predictive model that integrates it with the ETVSS is the most appropriate approach for selecting patients for ETV.

A re-evaluation of the Endoscopic Third Ventriculostomy Success Score: a Hydrocephalus Clinical Research Network study.

OBJECTIVE: The Hydrocephalus Clinical Research Network (HCRN) conducted a prospective study 1) to determine if a new, better-performing version of the Endoscopic Third Ventriculostomy Success Score (ETVSS) could be developed, 2) to explore the performance characteristics of the original ETVSS in a modern endoscopic third ventriculostomy (ETV) cohort, and 3) to determine if the addition of radiological variables to the ETVSS improved its predictive abilities. METHODS: From April 2008 to August 2019, children (corrected age ≤ 17.5 years) who underwent a first-time ETV for hydrocephalus were included in a prospective multicenter HCRN study. All children had at least 6 months of clinical follow-up and were followed since the index ETV in the HCRN Core Data Registry. Children who underwent choroid plexus cauterization were excluded. Outcome (ETV success) was defined as the lack of ETV failure within 6 months of the index procedure. Kaplan-Meier curves were constructed to evaluate time-dependent variables. Multivariable binary logistic models were built to evaluate predictors of ETV success. Model performance was evaluated with Hosmer-Lemeshow and Harrell's C statistics. RESULTS: Seven hundred sixty-one children underwent a first-time ETV. The rate of 6-month ETV success was 76%. The Hosmer-Lemeshow and Harrell's C statistics of the logistic model containing more granular age and etiology categorizations did not differ significantly from a model containing the ETVSS categories. In children ≥ 12 months of age with ETVSSs of 50 or 60, the original ETVSS underestimated success, but this analysis was limited by a small sample size. Fronto-occipital horn ratio (p = 0.37), maximum width of the third ventricle (p = 0.39), and downward concavity of the floor of the third ventricle (p = 0.63) did not predict ETV success. A possible association between the degree of prepontine adhesions on preoperative MRI and ETV success was detected, but this did not reach statistical significance. CONCLUSIONS: This modern, multicenter study of ETV success shows that the original ETVSS continues to demonstrate good predictive ability, which was not substantially improved with a new success score. There might be an association between preoperative prepontine adhesions and ETV success, and this needs to be evaluated in a future large prospective study.

Stereotactic anatomy of the third ventricle.

PURPOSE: Endoscopic third ventriculostomy (ETV) is a surgical procedure that can lead to complications and requires detailed preoperative planning. This study aimed to provide a more accurate understanding of the anatomy of the third ventricle and the location of important structures to improve the safety and success of ETV. METHODS: We measured the stereotactic coordinates of six points of interest relative to a predefined stereotactic reference point in 23 cadaver brain hemi-sections, 200 normal brain magnetic resonance imaging (MRI) scans, and 24 hydrocephalic brain MRI scans. The measurements were statistically analyzed, and comparisons were made. RESULTS: We found some statistically significant differences between genders in MRIs from healthy subjects. We also found statistically significant differences between MRIs from healthy subjects and both cadaver brains and MRIs with hydrocephalus, though their magnitude is very small and not clinically relevant. Some stereotactic points were more posteriorly and inferiorly located in cadaver brains, particularly the infundibular recess and the basilar artery. It was found that all stereotactic points studied were more posteriorly located in brains with hydrocephalus. CONCLUSION: The study describes periventricular structures in cadaver brains and MRI scans from healthy and hydrocephalic subjects, which can guide neurosurgeons in planning surgical approaches to the third ventricle. Overall, the study contributes to understanding ETV and provides insights for improving its safety and efficacy. The findings also support that practicing on cadaveric brains can still provide valuable information and is valid for study and training of neurosurgeons unfamiliar with the ETV technique.

Usefulness of third ventricle volumetry in patients with normal pressure hydrocephalus.

OBJECTIVE: To use third ventricle morphometric variables as a tool for the selection of patients with idiopathic normal pressure hydrocephalus (iNPH) who are candidates for ventriculoperitoneal shunts (VPS). MATERIAL AND METHODS: Retrospective study enrolling patients with iNPH. Katzman infusion test was performed and a Rout > 12 mmHg/mL/min was considered a positive result. The transverse diameter and the volume of the third ventricle were measured in the preoperative MRI. Postoperative improvement was assessed with the NPH score. The results were analysed with SPSS software. RESULTS: 52 patients with a mean age of 76 years were analysed. There was no difference in the diameter of the third ventricle among patients with a positive result and those with a negative result in the infusion test (12.28 vs 11.68 mm; p = 0.14). Neither were difference detected in the ventricle volume of both groups (3.6 vs 3.5cc; p = 0.66). Those patients who improved after VPS had a smaller third ventricle compared to those who did not respond after surgery (11.85 mm vs. 12.96 mm; p = 0.009). Diameter and volume of third ventricle present a significant strong correlation (Pearson correlation coefficient = 0.72; p < 0.0001). CONCLUSION: Morphometric variables of third ventricle may be useful in predicting a good response to VPS in patients with idiopathic normal pressure hydrocephalus.

Dorsum Sellae as Key Landmark in ETV With Disminished Prepontine Cistern: Technical Note and Case Series.

BACKGROUND AND OBJECTIVES: One of the key aspects in the surgical technique of endoscopic third ventriculostomy (ETV) is the perforation of the floor of the third ventricle because of the high risk of injuring vital structures located in that region. According to the standard technique, this perforation should be performed in the midline halfway between mammillary bodies and the infundibular recess to avoid damage to the structures. This can be performed without excessive complications when the diameter of the prepontine cistern is wide. However, in situations where the diameter is reduced (defined in the literature as having a prepontine interval [PPI] ≤1 mm), the probability of complications increases exponentially.In this article, we propose using dorsum sellae as a key point to safely perform ETV in patients with a decreased PPI, guiding the trajectory and its marking using neuronavigation. METHODS: A review was conducted on the latest 100 ETV procedures performed by our team in the past 5 years. The measurement of the PPI was conducted using archived preoperative MRI imaging studies, specifically between the dorsum sellae and the basilar artery. In cases where the PPI was ≤1 mm and, therefore, the use of the dorsum sellae was applied as a reference point, the technical results and procedural functions were documented. RESULTS: In the cohort, 7 patients with a PPI ≤1 mm were identified. In all 7 cases, fenestration of the tuber cinereum was successfully performed without causing vascular damage or associated complications. ETV was successful in 6 patients, with only one experiencing ETV failure necessitating the placement of a ventriculoperitoneal shunt. CONCLUSION: The utilization of the dorsum sellae as a reference point to perform ETV in reduced PPI constitutes a safe alternative to the classical technique.

Colloid Cyst: Revision of Third Ventricular Zones for Risk Stratification of Hydrocephalus.

OBJECTIVE: We sought to reclassify the "anatomic risk zones of colloid cysts" as proposed by Beaumont et al, by proposing newer landmarks, and to assess predictive value for the risk of occurrence of hydrocephalus with the new classification compared with the old. METHODS: A retrospective cohort of 122 cases of colloid cyst of third ventricle were categorized into zones 1, 2, or 3 based on Beaumont's classification (old zone) and our classification (new zone) based on radiologic images. We attempted to recategorize these zones by assigning new anatomic landmarks. The difference in zonal distribution of colloid cyst and association with hydrocephalus was studied using the 2 methods of zonal classification. RESULTS: Per the old zone classification, 3/122 patients were in zone 2, whereas 21/122 were in zone 2 per the new zone classification. The new zone method had a higher specificity (36.21% vs. 5.263 %) and positive predictive value (63.37% vs. 54.23%) for occurrence of hydrocephalus in patients with colloid cyst. The Spearman correlation showed better correlation with the new method for occurrence of hydrocephalus (rho = 0.4 [P < 0.00000] vs. 0.2 [P = 0.011]). CONCLUSIONS: Symptomatic colloid cysts are more likely to develop hydrocephalus and sudden acute deterioration. The colloid cyst risk score is a step towards objective decision making, with scope for modification such as the one that we have attempted with new zone classification to achieve superior prognostic ability.

Endoscopic third ventriculostomy (ETV) or ventriculoperitoneal shunt (VPS) for paediatric hydrocephalus due to primary aqueductal stenosis.

PURPOSE: The purpose of this study was to compare outcomes of endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt (VPS) in children with symptomatic triventricular hydrocephalus due to primary aqueductal stenosis. METHOD: This is a retrospective analytical study. Patients who underwent either ETV or VPS as the first procedure for hydrocephalus due to primary aqueductal stenosis were included in the study. RESULT: A total of 89 children were included in the study for analysis. The mean age was 8.4 years. Forty-four (49.4%) had their first surgery as ETV and 45 (50.6%) had their first surgery as VPS. Overall, 34 (38.2%) patients required a second surgery (either ETV or VPS) for persistent or recurrent hydrocephalus. The mean follow-up duration was 832.9 days. The overall complication rate was 13.5%. The mean timing of the second surgery after index surgery was 601.35 days. Factors associated with a second surgery were the presence of complications, high protein in cerebrospinal fluid, the relative change of frontal-occipital horn ratio (FOHR) and Evans' index. The survival of the first surgery was superior in ETV (751.55 days) compared to VPS (454.49 days), p = 0.013. The relative change of fronto-occipital horn index ratio (FOIR) was high in the VPS (mean 7.28%) group compared to the ETV (mean 4.40%), p = 0.001 group. CONCLUSION: Overall procedural survival was better after ETV than VPS for hydrocephalus due to aqueductal stenosis. VPS causes more reduction in linear indices of ventricles as compared to ETV, however, is not associated with the success or complication of the procedure.

Third ventricular width by transcranial sonography is associated with cognitive impairment in Parkinson's disease.

BACKGROUND: One-fourth of Parkinson's disease (PD) patients suffer from cognitive impairment. However, few neuroimaging markers have been identified regarding cognitive impairment in PD. OBJECTIVE: This study aimed to explore the association between third ventricular width by transcranial sonography (TCS) and cognitive decline in PD. METHOD: Participants with PD were recruited from one medical center in China. Third ventricular width was assessed by TCS, and cognitive function was analyzed by the Mini-Mental State Examination (MMSE). Receiver operating characteristic (ROC) analysis and Cox model analysis were utilized to determine the diagnostic and predictive accuracy of third ventricular width by TCS for cognitive decline in PD patients. RESULT: A total of 174 PD patients were recruited. Third ventricular width was negatively correlated with MMSE scores. ROC analysis suggested that the optimal cutoff point for third ventricular width in screening for cognitive impairment in PD was 4.75 mm (sensitivity 62.7%; specificity 75.6%). After 21.5 (18.0, 26.0) months of follow-up in PD patients without cognitive impairment, it was found that those with a third ventricular width greater than 4.75 mm exhibited a 7.975 times higher risk of developing cognitive impairment [hazard ratio = 7.975, 95% CI 1.609, 39.532, p = 0.011] compared with patients with a third ventricular width less than 4.75 mm. CONCLUSION: Third ventricular width based on TCS emerged as an independent predictor of developing cognitive impairment in PD patients.