Ali Mahdavi

Developing optimized fMRI protocol for clinical use: comparison of different language paradigms.

To compare the potential of five functional magnetic resonance imaging (fMRI) language paradigms in activating language areas in Persian‐speaking volunteers in order to optimize these tasks for clinically useful protocol.

Nonneural congenital abnormalities concurring with myelomeningocele: report of 17 cases and review of current theories.

Objective: Meningomyelocele (MMC) is a common central nervous system birth defect. Various congenital and acquired abnormalities have been reported with MMC, some of which are secondary to the pathophysiology and some are morbidities of the underlying disease. The aim of this study was to discuss current possible theories explaining diverse anomalies/abnormalities seen in a series of 390 patients with MMC. Methods: A retrospective study was performed using the records of 390 patients with MMC at Children’s Hospital Medical Center in Tehran, Iran, from January 2001 to January 2007. A series of 17 cases of MMC with attributed organ anomalies, not explained by a causal effect of the underlying disorder, were compiled. There were 3 cardiac anomalies including ventricular septal defect, pulmonary artery atresia and tetralogy of Fallot, 4 musculoskeletal malformations, consisting of missing rib, polydactylia and complex distal limb anomaly, 4 urological anomalies such as bladder exstrophy, horseshoe kidney and dysplastic kidneys, 2 occipital encephaloceles, 2 congenital adrenal hyperplasia patients with ambiguous genitalia, 1 omphalocele, 1 albinism and 1 Klippel-Feil syndrome. A review of the literature and discussion explaining each of these observations, have been performed and some possible theories have been proposed.Conclusions: Although various organ anomalies with different embryological origin had been observed and reported with MMC, it is difficult to explain their development using one of the current theories of MMC formation. It could be attributed to a possible genetic defect or merely an incidental finding. A teratological insult during the embryogenic phase would be an alternative assumption.

Recurrent meningitis caused by cervico-medullary abscess, a rare presentation.

BackgroundRecurrent bacterial meningitis is usually a complication of cranial anatomical defect or the result of impaired humoral immunity, notably, defects of the complement system and agammaglobulinemia. It could present a diverse range of symptoms.DiscussionMeningitis as a presentation of intramedullary abscess is not common. Here we present a 7-year-old boy with recurrent meningitis as the first manifestation of an underlying upper cervical cord abscess.

Lumbosacral Sagittal Alignment in Association to Intervertebral Disc Diseases

Study Design A cross-sectional case-control study was designed to compare the sagittal alignment of lumbosacral regions in two groups of patients suffering from low back pain, one with intervertebral disc pathologies and one without. Purpose To evaluate the correlation between lumbosacral sagittal alignment and disc degeneration. Overview of Literature Changes in lumbar lordosis and pelvic parameters in degenerative disc lesions have been assessed in few studies. Overall, patients with discopathy were shown to have lower lumbar lordosis and more vertical sacral profiles. Methods From patients with intractable low back pain undergoing lumbosacral magnetic resonance imaging, 50 subjects with disc degeneration and 50 controls with normal scans were consecutively enrolled. A method was defined with anterior tangent-lines going through anterior bodies of L1 and S1 to measure global lumbosacral angle, incorporating both lumbar lordosis and sacral slope. Global lumbosacral angle using the proposed method and lumbar lordosis using Cobbs method were measured in both groups. Results Lumbar lordosis based on Cobbs method was lower in group with discopathy (20°-67°; mean, 40.48°±9.89°) than control group (30°-62°; mean, 44.96°±7.68°), although it was not statistically significant. The proposed global lumbosacral angle in subject group (53°-103°; mean, 76.5°±11.018°) was less than control group (52°-101°; mean, 80.18°±9.95°), with the difference being statistically significant (p=0.002). Conclusions Patients with intervertebral disc lesions seem to have more straightened lumbosacral profiles, but it has not been proven which comes first: disc degeneration or changes in sagittal alignment. Finding an answer to this dilemma demands more comprehensive long-term prospective studies.

Functional MRI in clinical practice: Assessment of language and motor for pre-surgical planning.

Functional magnetic resonance imaging (fMRI) has been widely used for pre-neurosurgical planning and may eventually become a routine pre-surgical imaging modality. The validity of fMRI for clinical application depends on various factors such as proper task selection, correct statistical analysis and threshold setting with appropriate patient cooperation. This study was performed on 40 patients with different types of brain mass lesions or hippocampal sclerosis to assess the role of appropriate patient selection for achieving a reliable fMRI result. Accurate and reproducible fMRI strongly depends on the patient’s cooperation. In this study we observed that a pre-test mock fMRI session held by a radiologist may help to predict which patients are more or less suitable candidates for fMRI.

Sudden deterioration due to intra-tumoral hemorrhage of ependymoma of the fourth ventricle in a child during a flight: a case report

IntroductionTo the best of our knowledge, the association between air travel and intra-tumoral hemorrhage in pediatric populations has never been described previously.Case presentationWe report the case of a two-and-a-half-year-old Caucasian, Iranian boy with a hemorrhaging brain tumor. He had a posterior fossa midline mass and severe hydrocephalus. He had been shunted for hydrocephalus four weeks earlier and was subsequently referred to our center for further treatment. The hemorrhage occurred in an infra-tentorial ependymoma, precipitated by an approximately 700-mile air journey at a maximum altitude of 25,000 feet.ConclusionsA pre-existing intra-cranial mass lesion diminishes the ability of the brain to accommodate the mild environmental disturbances caused by hypercarbia, increased venous pressure and reduced cerebral blood flow during long air journeys. This is supported by a literature review, based on our current knowledge of physiological changes during air travel.

Brain abscess as a manifestation of spinal dermal sinus

Dermal sinuses have been associated with a wide spectrum of clinical manifestations ranging from asymptomatic to drainage of purulent material from the sinus tract, inclusion tumors, meningitis, and spinal abscess. To date, there has been no documented report of brain abscess as a complication of spinal dermal sinus. Here, we report an 8-month-old girl who was presented initially with a brain abscess at early infancy but lumbar dermal sinus and associated spinal abscess were discovered afterwards. The probable mechanisms of this rare association have been discussed.

Hanging Bladder calculi Secondary to Misplaced Surgical Suture

Bladder calculi, a rare condition in the pediatric population, occur most commonly as a result of either migration from the kidney or urinary stasis in the bladder. We report the case of a 3-year-old boy with recurrent urinary tract infections (UTI) secondary to bladder calculi formation on the sutures from a previous herniorrhaphy.A 3-year-old boy with previous history of herniorrhaphy presented with recurrent episodes of urinary tract infection, resistant to antibiotic therapy. Physical examination was unremarkable. Ultrasonography (US) showed an echogenic fixed intra-luminal lesion in the bladder. Cystoscopic evaluation was performed and confirmed presence of calculi forming around several permanent silk sutures fixed to the bladder wall. The patient undergone cystotomy and the calculi were resected. The stone analysis revealed 80% uric acid calculi. The final diagnosis was of bladder calculi due to remnant suture from past herniorrhaphy.

Neurophysiological analysis of schizophrenia based on dysfunction of the glutamatergic system using a tripartite synapse model

Schizophrenia is a severe chronic psychiatric disorder and its pathology is still not completely known. However, up to now several different theories have been proposed to describe the pathophysiology of schizophrenia. Hypofunction of NMDA receptors (NMDAR) and inactivated astrocytes are among important glutamatergic theories explaining the pathophysiology of schizophrenia. On the other hand, it has been suggested that pharmacological manipulation of presynaptic metabotropic glutamate receptors (mGluRs) may help to treat and improve some symptoms of schizophrenia. In this paper we propose a mathematical model at the synaptic level to investigate glutamatergic hypothesis of schizophrenia. In the proposed model, we described mathematically a single tripartite synapse that is consisted of one presynaptic and one postsynaptic neuron and a glial component that is the astrocyte. The proposed model describes different details of a tripartite synapse during glutamate release. To the best of our knowledge, at the moment this is the most extended mathematical model developed to describe the details of a tripartite synapse to this extend. Simulation results of the proposed model indicate that hypofunction of NMDAR might be caused by excessive amount of glutamate in the synaptic cleft. The increased amount of glutamate, in final analysis, can be caused by inactive astrocyte. The increased amount of glutamate in synaptic cleft may cause serious disturbances in NMDAR current and electrophysiological behavior of the postsynaptic neuron. Given these results, we suggest that manipulation of glutamate receptors on astrocyte may be a suitable strategy in the treatment of schizophrenia. Of course, other approaches that help to improve the function of glutamate transmission or use agonists of mGluRs or NMDARs might be also useful. Our simulation results also suggest that the mentioned theories about pathophysiology of schizophrenia are interrelated and the increased rate of clearance of glutamate from the synaptic cleft can partly compensate for disorders caused by the impaired astrocyte.

A mathematical model for neuron astrocytes interactions in hippocampus during addiction

Addiction is a chronic disorder whereby addicted individuals compulsively engage in drug seeking despite its negative consequences. Hippocampus has unavoidable role in addiction because of its importance in learning and memory. Any modification of hippocampal cells alters dopamine levels in NAc and firing rates of VTA dopaminergic cells. In order to have a better understanding of the addiction in cellular level, we present a mathematical model of a tripartite synapse in hippocampus. The proposed model can show some functions of synapses under addiction that may contribute to drug seeking and relapse behaviors. The model is based on glutamate alterations in synaptic cleft during drug abuse. Experimental studies suggest that during drug abuse, NMD AR dependent synaptic transmission is increased. According to our simulation results, dysfunction of astrocyte has a significant role in initiating addiction. Since healthy astrocytes has a comprehensive control over synaptic interactions it may use to treat addicted related behaviors. Also, we may conclude that addiction causes abnormalities on postsynaptic signaling such as NMDA currents. Furthermore, we may suggest that drug induced D-serine enhancement in synaptic cleft potentiate post synaptic calcium influx and LTP.