All Publications

  • Feasibility of percutaneous dural sac puncture via a posterior trans-sacral foraminal conduit approach: a CT morphometric analysis. Neuroradiology Dhawan, S. S., Necker, F. N., Massoud, T. F. 2023


    We assess the theoretical feasibility of percutaneous posterior sacral foramen (pSF) needle puncture of the sacral dural sac (DS) by studying the three-dimensional imaging anatomy of pSFs relative to the sacral canal (SC). On CT images of 40 healthy subjects, we retrospectively studied sacral alae passageways from SC to pSFs in all three planes to determine if an imaginary spinal needle could theoretically traverse S1 or S2 pSFs in a straight path toward DS. If not straight, we measured multiplane angulations and morphometrics of this route. We found no straight connections between S1 or S2 pSFs and SC. Instead, there were bilateral spatially complex dorsoventral M-shaped "foraminal conduits" (FCs; common, ventral, and dorsal) from SC to anterior SFs and pSFs that would prevent percutaneous straight needle puncture of the DS. This detailed knowledge of the sacral FCs will be useful for accurate imaging interpretation and interventional procedures on the sacrum.

    View details for DOI 10.1007/s00234-023-03147-4

    View details for PubMedID 37022486

    View details for PubMedCentralID 7959916

  • Caudolenticular Gray Bridges of the Brain: A Magnetic Resonance Imaging Study. Clinical anatomy (New York, N.Y.) Dang, B., Necker, F. N., Dhawan, S. S., Murty, T., Massoud, T. F. 2023


    The caudolenticular (or transcapsular) gray bridges (CLGBs) connect the caudate nucleus (CN) and putamen across the internal capsule. The CLGBs function as the main efferent terminus from premotor and supplementary motor area cortex to the basal ganglia (BG). We conjectured if inherent variations in numbers and sizes of CLGBs could contribute to abnormal cortical-subcortical connectivity in Parkinson's disease (PD), a neurodegenerative disorder featuring a hindrance of BG processing. However, there are no literature accounts of normative anatomy and morphometry of CLGBs. We therefore retrospectively analyzed axial and coronal 3T FSPGR MRIs of 34 healthy individuals for bilateral CLGBs symmetry, their numbers, dimensions of thickest and longest bridge, and axial surface areas of CN head and putamen. We calculated Evans' index (EI) to account for any brain atrophy. We statistically tested associations between sex or age and measured dependent variables, and linear correlations between all measured variables (significance at p<.05). Study subjects were F:M=23:11 with mean age 49.9 years. All EI's were normal (<.3). All but three CLGBs were bilaterally symmetrical with a mean 7.4 CLGBs per side. Mean CLGBs thickness and lengths were 1.0mm and 4.6mm, respectively; CN head and putamen areas were 205mm2 and 382.0mm2 , respectively. Females had thicker CLGBs (p=.02) but we found no significant interactions between sex or age and measured dependent variables, and no correlations between CN head or putamen areas and CLGBs dimensions. These normative MRI dimensions of the CLGBs will help guide future studies on the possible role of CLGBs morphometry in PD predisposition.

    View details for DOI 10.1002/ca.24026

    View details for PubMedID 36795325

  • Atavistic and vestigial anatomical structures in the head, neck, and spine: an overview. Anatomical science international Dhawan, S. S., Yedavalli, V., Massoud, T. F. 2023


    Organisms may retain nonfunctional anatomical features as a consequence of evolutionary natural selection. Resultant atavistic and vestigial anatomical structures have long been a source of perplexity. Atavism is when an ancestral trait reappears after loss through an evolutionary change in previous generations, whereas vestigial structures are remnants that are largely or entirely functionless relative to their original roles. While physicians are cognizant of their existence, atavistic and vestigial structures are rarely emphasized in anatomical curricula and can, therefore, be puzzling when discovered incidentally. In addition, the literature is replete with examples of the terms atavistic and vestigial being used interchangeably without careful distinction between them. We provide an overview of important atavistic and vestigial structures in the head, neck, and spine that can serve as a reference for anatomists and clinical neuroscientists. We review the literature on atavistic and vestigial anatomical structures of the head, neck, and spine that may be encountered in clinical practice. We define atavistic and vestigial structures and employ these definitions consistently when classifying anatomical structures. Pertinent anatomical structures are numerous and include human tails, plica semilunaris, the vomeronasal organ, levator claviculae, and external ear muscles, to name a few. Atavistic and vestigial structures are found throughout the head, neck, and spine. Some, such as human tails and branchial cysts may be clinically symptomatic. Literature reports indicate that their prevalence varies across populations. Knowledge of atavistic and vestigial anatomical structures can inform diagnoses, prevent misrecognition of variation for pathology, and guide clinical interventions.

    View details for DOI 10.1007/s12565-022-00701-7

    View details for PubMedID 36680662

  • Feasibility of Intrathecal Therapeutic Injections in Spinal Muscular Atrophy Patients via a Percutaneous Trans-Sacral Hiatus Route: An Initial Neuroimaging Morphometric Study. Muscle & nerve Dhawan, S. S., Trinh, A., Massoud, T. F. 2022


    INTRODUCTION/AIMS: Standard fluoroscopic lumbar puncture (LP) can be impossible in patients with severe spinal deformities from spinal muscular atrophy (SMA) who require intrathecal nusinersen therapy. There usually exists a straight trajectory in the lower sacral canal (SC) that could allow image-guided percutaneous trans-sacral hiatus puncture of the lumbosacral dural sac. Here, we determine if sacra are comparatively straighter in SMA patients (SMAps) versus healthy controls (HCs), which may facilitate unhindered trans-sacral hiatus spinal needle insertion for intrathecal nusinersen therapy.METHODS: We retrospectively analyzed lumbosacral spine computed tomograms (CTs) or CT-myelogram images of 38 SMAps and age- and sex-matched HCs. We digitally measured ventrodorsal sacral curvatures, SC surface areas, dural sac termination levels, and distances from sacral hiatus to the most caudad aspects of dural sacs ('needle distance').RESULTS: Mean ages of HCs and SMAps were 32.7 and 31.7years, respectively, with dural sacs terminating at similar levels. Mean values for morphometrics were: (a) Midsagittal SC surface area for HCs=701.2mm2 , and for SMAps=601.5mm2 (ns). (b) Using a 'line method', sacral curvature for HCs=61.9°, and SMAp=35.7° (p =0.0009), and was similar when using an 'angle summation method'. (c) Width of sacral hiatus for HCs=14.9mm, and SMAps=15.0mm (ns). (d) 'Needle distance' for HCs=54.7mm, and SMAps=49.9mm (ns).DISCUSSION: SMAps have significantly straighter sacra compared to HCs, which theoretically renders them more amenable to percutaneous trans-sacral hiatus puncture of the dural sac. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/mus.27782

    View details for PubMedID 36576208