Medullary Compression Research Articles

Successful Treatment with Microvascular Decompression Surgery of a Patient with Hemiparesis Caused by Vertebral Artery Compression of the Medulla Oblongata: Case Report and Review of the Literature

There are few reports on hemiparesis caused by vascular medullary compression, which can occur because of dolichoectasia of the vertebrobasilar arterial system. In this article, we report a case of vertebral artery compression of the medulla oblongata in a 67-year-old woman. The patient was hypertensive, and she developed hemiparesis and intermittent spasms over 5 years. These spasms had worsened during the last year. Cranial nerve magnetic resonance imaging showed compression of the medulla oblongata by the left vertebral artery. A motor evoked potential (MEP) examination showed abnormal conduction of MEPs of bilateral toe abductors. The patient underwent microvascular decompression surgery under general anesthesia through a retrosigmoid keyhole approach. This operation led to relief of vascular compression and symptomatic improvement. Our case suggests that detailed history, imaging studies, and electrophysiologic studies help lead to a correct and early diagnosis of hemiparesis caused by vascular compression of the rostral ventrolateral medulla. Microvascular decompression surgery improves patient symptoms, and intraoperative electrophysiologic monitoring helps to avoid injury to important adjacent nerves.

Quantitative approach to the posterior cranial fossa and craniocervical junction in asymptomatic children with achondroplasia.

We propose an magnetic resonance imaging (MRI)-based quantitative morphovolumetric approach to the posterior cranial fossa (PCF) and craniocervical junction (CCJ) changes in achondroplastic patients investigating possible associations with ventriculomegaly and medullary compression. We analyzed MRI of 13 achondroplastic children not treated by surgery. 3D FSPGR T1-weighted images were used to analyze (1) PCF synchondroses; (2) PCF volume (PCFV), PCF brain volume (PCFBV), PCFV/PCFBV ratio, cerebellar volume, cerebrospinal fluid (CSF) spaces volume, and IV ventricle volume; (3) PCF (clivus, supraocciput, exocciput lengths, tentorial angle) and CCJ (AP and LL diameters of foramen magnum (FM)) morphometry; (4) measurements of FM and jugular foramina (JF) areas; and (5) supratentorial ventricular volume. All patients showed synostosis of spheno-occipital synchondroses, eight showed synostosis of intra-occipital synchondroses, nine showed CCJ impingement on the cervical cord but only three had cervical myelopathy. Compared to controls, clivus and exocciput lengths, LL and AP diameters of FM, FM area and JF area were significantly reduced, supraocciput length, tentorial angle, PCFV, PCFBV, cerebellar volume, supratentorial ventricular system volume were significantly increased. A correlation was found between clivus length and supratentorial ventricular volume, premature closure of intra-occipital synchondroses and FM area while a trend was found between FM area and supraocciput length. Our analysis demonstrates a relationship between the shortening of the clivus and the ventriculomegaly. On the other hand the premature closure of PCF synchondroses, the shape, and the growth direction of supraocciput bone contribute to reduce the FM area, causing in some patients medullary compression.

Medullary vertebral compression in primary hyperparathyroidism

Medullary vertebral compression in primary hyperparathyroidism

P136 - Medullary compression secondary to a metastatic breast tumor

P136 - Medullary compression secondary to a metastatic breast tumor

Does Dynamic Supine Magnetic Resonance Imaging Improve the Diagnostic Accuracy of Cervical Spondylotic Myelopathy? A Review of the Current Evidence.

We aimed to critically analyze the current evidence regarding the role of dynamic supine magnetic resonance imaging (dsMRI) in the evaluation of cervical spondylotic myelopathy. Thirteen studies were identified through a comprehensive literature search performed in the PubMed, EMBASE, and ISI databases as fulfilling the inclusion criteria and were reviewed for subject characteristics, radiographic parameters, and salient findings. Studies herein reviewed suggested that dsMRI was able to detect new appearance or increased grade of medullary compression in ≥20% of patients and to demonstrate an average narrowing of the cervical canal by 20% (in comparison with the neutral position). Several additional parameters were investigated, but their clinical significance remained unconfirmed. Two studies examined how surgical decision-making could be affected by the additional findings of dsMRI. dsMRI represents an available modification of conventional static magnetic resonance imaging and is potentially able to demonstrate pathologies that might be previously missed. Evidence suggests that dsMRI can elucidate spinal cord compression with higher sensitivity, resulting in improved diagnostic accuracy of cervical spondylotic myelopathy, which may impact surgical planning for these patients. However, more high-quality studies are required to further establish its indications to avoid overdiagnosis with this powerful imaging technique and to justify its cost-effectiveness.

Compression-distraction reduction surgical verification and optimization to treat the basilar invagination and atlantoaxial dislocation: a finite element analysis.

BackgroundBasilar invagination (BI) combined with atlantoaxial dislocation (AAD) leads to foramen magnum stenosis and medullary spinal cord compression, causing nerve dysfunction. The purpose of the surgery is to remove the bony compression at brainstem ventral side and fix the unstable spinal segment and make it fused stably. Occipital cervical internal fixation system that simultaneously reduces atlantoaxial horizontal and vertical dislocation are established. We propose here a new compression-distraction reduction (CDR) technique. We aimed to construct a congenital BI-AAD preoperative finite element model (FEM) to simulate the CDR technique for AAD reduction surgery.MethodsBased on computed tomographic scans of patients’ cervical vertebrae, a three-dimensional (3D) geometric model of the cervical spine (C0–C4) of congenital BI-AAD patients was established using Mimics13.1, Geomagic2012, and Space Claim14.0 softwares. The mechanical parameters of the tissues were assigned according to their material characteristics using ANSYS Workbench 14.0 software. A 3D FEM was established using the tetrahedral mesh method. The bending moment was loaded on C0. Physiological conditions—anteflexion, retroflexion, left and right flexion, left and right rotation—were simulated for preoperative verification. The occipital cervical fixation system FEM was established. The CDR technique was simulated to perform AAD reduction surgery. Data were obtained when the atlantoaxial horizontal and vertical dislocation reductions were verified postoperatively. Stress data for the two surgical schemes were analyzed, as was the reduction surgery optimization scheme for congenital BI-AAD patients with abnormal lateral atlantoaxial articulation ossification.ResultsCervical spine (C0–C4) FEM of congenital BI-AAD patients was established. The CDR technique was simulated for AAD reduction. We obtained the mechanical data when the atlantoaxial horizontal and vertical dislocation reductions were satisfied for the two surgical schemes.ConclusionsThe CDR technique for AAD reduction was feasible and effective. We propose this reduction optimization scheme for patients with lateral atlantoaxial articulation due to abnormal ossification of congenital BI-AAD. We also provide a biomechanically theoretical basis for improving the reliability of pure posterior reduction surgery and simplifying surgery for complicated BI-AAD disease.

Management of Spinal Tuberculosis (TB) in Developing Country

Background: Tuberculosis on the spine is involved approximately 1 % of all tuberculosis cases. It is a lethal type of TB skeletal due to highly neurologic compromised because of adjacent medullary compression and incidence kyphotic deformity. Early diagnosis and management of this disease is mandatory to prevent serious complications. Method: Serial case report was conducted in Sanglah General Hospital from January 2014 until December 2015. All patients were diagnosed based on local protocol using appropriate imaging technique. All patients were treated by anti-tuberculosis drugs for 2 weeks followed by functional assessment by MMT, ASIA, and JOA. Result: The author reported 10 patients of spinal TB whom were treated in Sanglah Hospital, Bali between January 2014- Desember 2015. Among pts 8 male and 2 female with location of spinal TB i.e 4 in thoracal, 4 in lumbal and 2 in cervicothoracal. Preoperative ASIA scale was an average scale C and postoperative ASIA scale was in D. The average JOA pre-surgical score was 10.5 and postsurgical was 14.5. Improvement using the formula JOA achieved with an average of 21.6 %. All patients neurologically improved, no complications and surgical implant failures in this series. Conclusions: Surgical management of spinal tuberculosis, if delivered with appropriate indication, proved to be effective in correcting spinal kyphosis. Early management is mandatory in order to ensure better prognosis.

Degenerative Changes in the Cervical Spine Are More Common in Middle-Aged Individuals with Thalidomide Embryopathy than in Healthy Controls.

BackgroundThalidomide was used as a sedative drug for pregnant women in the 1950–60:s and resulted in children born with thalidomide embryopathy (TE), including upper limb malformations. These may alter the motion pattern of the cervical spine by the use of head/shoulder and mouth grip.AimsTo compare degenerative changes in the cervical spine in TE individuals with healthy controls (CTR).Methods and ProceduresTwenty-seven middle-aged TE individuals and 27 age- and gender-matched CTR were examined by cervical spine MRI. The presence of malformations, disc herniation(s), osteophytes, nerve and medullary compression and the degree of disc degeneration (DD) were evaluated.Outcomes and ResultsSignificantly higher degree of DD was seen in the TE group compared with the controls (p<0.001). Similar frequencies of disc herniation and disc space narrowing were observed in the two groups, but more foraminal narrowing was seen in the TE group (p = 0.002). DD was observed relatively frequently at all cervical levels in the TE group, however, mainly at the two lower levels in the CTR.Conclusions and ImplicationsMiddle-aged individuals with TE have a higher frequency of degenerative changes in the cervical spine than controls, possibly caused by an altered load on the cervical spine.

Degenerative Changes in the Cervical Spine are More Common in Middle-aged Patients with Thalidomide Embryopathy than in Healthy Individuals

Introduction The aim of the study was to compare the degree of degenerative changes in the cervical spine of thalidomide embryopathy (TE) patients−in whom upper limb malformations often necessitate help with grip function through the mouth or by head motion, and may thereby add extra load to the spine−with that in a control group (CTR). Material and Methods Twenty-seven middle-aged TE patients and 27 age- and gender-matched healthy CTR were examined by cervical MRI. The presence of malformations, disc herniations, osteophytes, nerves and medullary compression, were evaluated. Disc degenerations (DD), were graded according to the Pfirrmann classification. Results Similar frequencies of disc herniation and disc space narrowing were observed in both groups, but there was more foraminal narrowing in the TE group (ρ &lt; 0.002). Significantly more DD were seen in the TE group than in the controls (ρ &lt; 0.001). Evaluation of all discs ( n = 135 per group) showed Pfirrmann grade I in 0% of the TE group and 2% of the controls. Grade II was found in 3% and 36%, respectively, grade III in 46% and 50%, grade IV in 38% and 11%, and grade V in 13% and 0% (ρ &lt; 0.001). DD were observed frequently at all levels for the TE group, however mainly in the two lower levels for the CTR. Conclusion The more frequently observed degenerative changes of foraminal narrowing and disc signal changes in the TE group support the theory that a higher load on the cervical spine leads to earlier development of DD.

Revisiting the link between hypertension and hemifacial spasm.

The relationship between hypertension and hemifacial spasm (HFS) has been debated. Microvascular decompression surgery is effective in some HFS patients with uncontrolled hypertension. To address current gaps in knowledge, we conducted a meta-analysis of case-control studies that have examined the prevalence of hypertension in HFS patients compared to non-HFS controls. We also evaluated the implications and limitations of the pooled studies. We identified 62 studies from PubMed, The Cochrane Library, Web of Science and Scholar.google.com and six studies that fit our inclusion criteria were included. A random-effects model was used to derive the pooled estimate of the Odds Ratio. The data was plotted on a Forest plot. A pooled analysis involving 51585 subjects, 549 cases, 720 neurological controls and 50316 controls from the general population, showed that HFS patients had a higher chance of developing hypertension (OR = 1.72, 95% CI = (1.12, 2.31), p-value <0.001). The prevalence of hypertension was higher in HFS patients as compared to non-HFS patients. This meta-analysis highlights a positive correlation between hypertension and HFS. Blood pressure should be closely monitored during the follow-up of HFS patients. Preliminary links between ventrolateral medullary (VLM) compression and HFS should be further evaluated in future studies.

Lumbar Paget disease with spinal stenosis and conus medullaris compression

Lumbar Paget disease with spinal stenosis and conus medullaris compression

Thoracic sinus tract secondary to a wooden skewer penetrating the vertebral canal in a dog

A six-year-old neutered male mixed breed dog was referred to the hospital for investigation of a thoracic sinus tract located caudal to the right axillary region. CT scan revealed the...

Differentiated plasma cell myeloma presenting as a solitary spinal amyloidoma: A case report, possible pitfall and review to the literature

ObjectiveSolitary spinal amyloidoma is a rare entity. Amyloidomas consist of extracellular amyloid deposits with an insoluble beta-pleated proteinaceous material. Although amyloidomas are slow growing lesions, they may lead to a progressive spinal cord or nerve root compression. Moreover amyloidoma results in destruction of bone with consequence of progressive osteolysis. MethodThis study is a case presentation and review of the literature and should point out the need to explore any underlying diseases to guarantee the best therapy for the affected patient. In this case report we present a female patient with high-level paraparesis and lumbar stenosis in L2–L3 with combined spondylolisthesis (ASIA Impairemet Scale C). Paraparesis increased shortly after lumbar osteosynthesis. Contrast-enhanced MRI of the thoracic spine revealed medullary compression at the D5 level due to an epidural and paraspinal mass with concomitant bone infiltration. Operative decompression followed. Histopathological examination initially revealed amyloidoma. Finally the lesion was classified as a plasma cell myeloma. ResultsPlasma cell myeloma may rarely present as a solitary amyloidoma in the initial pathological examination with the potential to cause spinal cord compression associated to osteolytic lesions of the spine. ConclusionA thorough pathological work-up is mandatory in order to rule out differential diagnosis and exclude possible underlying diseases.

Primary Vertebral Lymphoma: Two Cases and Literature Review

Introduction Spinal non-Hodgkin lymphomas (NHL) seldom affect spinal cord as first presentation, as there are mostly extradural initially. Usually presented in dorsal region, they are mostly high degree, aggressive, type B on diagnosis. We report two cases with spinal cord compression as first clinical manifestation. Patients and Methods The case reports of two cases of primary vertebral lymphoma from our service were presented. Results A 65 year-old-man had months-long back pain with sudden sphincter-sparing paraparesis; magnetic resonance imaging (MRI) showed prevertebral mass in T3 with vertebral body fracture and medullary compression. HIV testing was positive. Urgent decompressive surgery with tumor resection and stabilization yielded good recovery of motor function. A 69-year-old woman had 3 months of exercise-induced back pain and 10 days of paraplegia before coming to our service. MRI showed epidural invasion with medullary compression. Laminectomy and tumor resection were performed but without neurologic recovery. Burkitt lymphoma was diagnosed in both the cases. Conclusion We report two cases of aggressive NHL presenting as acute spinal cord compression requiring urgent surgical intervention. One of them on a background of undiagnosed HIV infection.

Cervical Spine Metastases: Our Experience

Introduction Metastases are the most frequent malignant lesions of the spine. Around 5 to 10% of the patients with a systemic tumor have got spinal metastases. More than 95% of spinal metastases are extradural lesions. The residual cases are intradural extramedullary lesions and only 0.5% are intramedullary lesions. Prostate, lung, breast, clear cell kidney tumors, lymphoma, myeloma, and gastric carcinoma are the most frequent primitive neoplasms to cause secondary lesions to the spine. The cervical spine is involved in 10% of the cases. In 80% of the cases, metastases are found to be in the lower cervical tract. Life expectancy in patients with lung carcinoma metastasis is approximately 6 months, 1.5/2 years in patients affected by breast, kidney, and prostate cancers. We reviewed our series of patients with spinal metastases operated between 1997 and 2013 with the aim to analyze the efficacy of the surgical treatment to recover the function and biomechanics of the vertebral column. We evaluated the prognosis in terms of duration and quality of residual life. Materials and Methods We included 36 patients (mean age 65 years). The patients were evaluated according to neurological status, Karnofsky score for the quality of life, and Denis score for pain. Indications for surgery were: pain resistant to pharmacological therapy, medullary compression, neurological deficits, and vertebral instability. Patients underwent CT and MR scan examinations of the cervical spine. In all patients, a total body CT scan was performed. All surgical procedures were performed with microsurgical techniques. In 25 cases, the surgical treatment contemplated an anterior approach: single corpectomy in 16 cases and double in 11 cases. In these cases, the vertebral body was replaced by an expandable titanium cage with PMMA filling and plating. In 6 cases, the treatment consisted of a 360-degree reconstruction. In the residual 5 cases, where the lesion was located in the superior cervical tract of the spine, we performed an occipital–cervical fusion through a posterior approach. Postoperative follow-up controls were run at 1, 3, 6, and 12 months. A cervical orthosis was worn by the patient for 40 days. Results During the follow-up time, 18 patients died because of the progression of the primitive tumor. In 36 patients treated with surgery, the histological examination documented a primitive lesion of the breast in 12 cases, of the lung in 10 cases, of the prostate in 5, of the kidney in 4, of the thyroid in 2, and of the testicle in 2. One patient affected by plasmacytoma was also observed. No intra- and perioperative complications arose. The neurological status was preserved intact in all cases with a sensible improvement in those patients affected by severe tetraparesis. We noticed a rise in the Karnofsky score, on an average from 70 to 85. Postoperative neuroimaging controls documented that the instrumentation was in the correct place. Conclusion Surgical treatment of spine metastases allows pain control, management of neurological conditions, and an overall improvement in the quality of residual life.

Spinal Neurocysticercosis: A Case Report

Introduction Neurocysticercosis (NCC) is the most common parasitic infection of the central nervous system. In endemic areas, the incidence of the NCC was approximately 4% of the general population. Although cerebral NCC is common, only 1 to 5% of cases demonstrate the involvement of the spinal canal. Great neurological morbidity can occur if spinal NCC is not adequate and opportunely. Patient and Methods: Male 70 years' old, with a history of cerebral NCC confirmed, DVP carrier, comes to our hospital emergency, with time of 5 months' duration disease, begins with paresthesias in the lower limbs, progressive loss of sphincter control, decreased strength in members inferiors difficult ambulation to prevent it. On admission, the patient lucid, sensitive level D6, paraplegia, hyperreflexia in the lower limbs, and sphincters unchecked. Dorsal spine MRI shows cystic lesion of 22 × 11 × 8 mm at D5 intradural extramedullary back and left side, which determines medullar compression. Surgery is performed consisting of laminectomy and partial D4, D5, D6, and more microsurgical resection of multiple cysts. Results Histopathological examination confirmed cysticercosis. Patient in postoperatorio is stable but unchanged in neurologic status despite the images confirmed decompression. Patient's motor weakness in the lower extremities and urinary function did not improve. Conclusion Spinal NCC can occur through direct hematogenous dissemination from the gastrointestinal tract. Spinal NCC may also be shown through the circulation of CSF. Doctors treating spinal cysts with an unusual clinical course should include cysticercosis as a differential diagnosis. MRI with contrast is recommended ELISA serum study in the diagnosis of these cases. Although spinal NCC is relatively rare, representing a distinct clinical entity that can have devastating consequences for the patient. Because of the limited size of the spinal canal, the effect of the mass of these lesions is not well tolerated.

Presentation of Case: Spinal Cord Compression and Cryptococcosis

Introduction Cryptococcosis is uncommon in man; preferentially affects pigeon breeders, birders, and laboratory workers. The advent of HIV has significantly increased its frequency. AIDS in adults is the main predisposing factor in over 80% of cases.1 The CDC (Center for Disease Control) in Atlanta states that only 1% of the population under 13 years infected with HIV contracted the disease.3,4 The cryptococcal yeasts are spherical, round, or oval, 3 to 8 mm in diameter; with the capsule, measuring up to 20 µm. They reproduce by budding only; are characterized by a narrow neck between mother and daughter cell. Exceptionally, multiple budding observed with elongated forms and pseudohyphae. The capsule polysaccharide nature is responsible for the virulence of the fungus as it protects against phagocytosis. The size of the yeast varies depending on the strain and culture medium used for isolation.1,2 Marrow cryptococcosis: This clinical form is secondary to the spread of a pulmonary focus, focus meningeal, or both. As in other fungal diseases, cryptococcus has a predilection for bony, skull bones, and vertebrae. In radiology, multiple, discrete, widely scattered, destructive lesions detected chronic evolution.3 The most common symptoms are swelling and pain in the affected area. An isolated bone lesion may be the only manifestation of the disease. There may be periostitis, osteolysis, and osteofibrosis. Occasionally, draining fistulae or mucoid material gave a seropurulent look to the skin.1,2 Material and Methods In this report we presented the case of a young man, with a 4-month history of evolution of back pain that evolves to progressive reduction of muscle strength in lower limbs both, forming a dorsal medullary compression of syndrome, with involvement of the vertebral bodies from D9 to D11 and extrinsic compression, of extradural spinal cord. At biopsy of the lesion, surprising finding performed notes as bone and soft tissue infiltration with yeast Cryptococcus neoformans. We use the clinical history, technique of the surgery, images of MRI, and the pathological report of the biopsy of the patient. Results Pathological result of marrow Cryptococcus neoformans. Conclusion Given the infrequency with which the marrow cryptococcosis occurs, even in immunocompetent individuals, and the few cases reported in the literature on spinal cord compression attributed to it, the therapy becomes complex to make this presentation before. Surgical options in cases of spinal cord compression with marrow cryptococcosis mainly depend on the anatomical site affected and the response to medical treatment. References Rippon JW. Criptococosis. In: Micología Médica. 3rd ed. Interamericana McGraw-Hill 1990:629 Perfect JR. Cryptococcosis. Infect Dis Clin North Am 1989;3(1):77–102 Powderly WG. Cryptococcal meningitis and AIDS. Clin Infect Dis 1993;17(5):837–842 Figueroa DR. Criptococosis meníngea no asociada con VIH. Rev Med IMSS 1999;37:127–132 Littman ML, Borok R. Relation of the pigeon to cryptococcosis: natural carrier state, heat resistance and survival of Cryptococcus neoformans. Mycopathol Mycol Appl 1968;35(3):329–345

Primary Solitary Retroclival Amyloidoma: A Case Report and Review of the Literature

Summary: Primary solitary amyloidoma of the spine is a rare disease characterized by focal deposition of amyloid. Here, we demonstrate the radiologic appearance of primary solitary amyloidoma of the spine on computed tomography and magnetic resonance imaging. The imaging findings revealed features of a nonspecific soft-tissue mass extending rostral and caudal from peri-C2 to the retroclivus with severe epidural cervical medullary compression.

An unusual association of von Hippel–Lindau disease and posterior nutcracker syndrome: Management of neurological and urological aspects in a young male

Von Hippel–Lindau disease is a complex and systemic entity that can be discovered by neurological complications. Its association with other serious malformative disease like Nutcracker syndrome was not described, and its complex presentation must not make some other serious problem easily missed or neglected. Case Report: We present the case of 27 year-old male patient with 3 intramedullary hemangioblastoma of 6 months of insidious evolution complicated by medullary compression. The lesions were completely removed with excellent neurological postoperatory outcome. Thinking of von Hippel-Lindau (VHL) disease, our investigations were expanded and revealed multiple vermian and cerebellar hemangioblastomas, renal masses, and multiple pancreatic cysts. In addition, an incidentally found of posterior NCS during the abdominal computed tomography (CT) done for VHL disease investigations. Our attitude to both neurosurgical and urological problems (the serious presentation of VHL disease with multiple locations of hemangioblastoma and right renal carcinomas) and for the missed symptomatic posterior Nutcracker syndrome were discussed. Conclusion: The complex presentation of the VHL disease must not makesome other serious problems easily missed or neglected like renal carcinoma or Nutcracker syndrome as seen in our case

Rare case of conus medullaris syndrome from a metastatic yolk sac tumor originating from the mediastinum of an adult male: a case report and review of the literature.

Yolk sac tumors (YST) are malignant neoplasms. They are a subtype of germ cell tumors and typically originate in the gonads although extragonadal origins of such tumors have been described. Yolk sac tumors are commonly found in the gonads of infants and children and are extremely rare in adults. The goal of this case report is to describe the clinical presentation of a rare case of metastatic extragonadal yolk sac tumor originating from the mediastinum and causing an acute conus medullaris syndrome in an adult male. A 47-year old male presented to our emergency department with a one-day history of bilateral lower extremity weakness, urinary retention and bowel incontinence. Imaging revealed a destructive lesion and a burst fracture of the first lumbar vertebral body (L1) with severe spinal canal stenosis. An urgent spinal decompression and fusion was performed. Oncologic workup revealed a yolk sac tumor originating from the mediastinum. His neurologic function, including motor strength, bowel and bladder function improved in the postoperative period. Chemotherapy regimen of ifosfamide, etoposide and cisplatin was administered and radiation therapy was administered to the spine tumor bed. Yolk sac tumors, although rare, should be considered in the long list differential diagnosis of an otherwise healthy male presenting with conus medullaris or spinal cord compression from metastatic disease without evidence of a testicular mass. Prompt diagnosis with urgent decompression of neural structures and stabilization of the spine may result in improvement in neurological function.