Knarik Arkun

Knarik Arkun
Tufts Medical Center · Boston Institute of Neurosurgery

Doctor of Medicine

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65
Publications
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773
Citations

Publications

Publications (65)
Article
Full-text available
Background A 63-year-old Black woman presented with progressive exertional dyspnea and chronic lower back pain. The course and findings in her case are instructive. Case report Family history was notable for cardiac deaths. An echocardiogram demonstrated ventricular wall thickening with diastolic dysfunction. The patient’s N-terminal pro b-type na...
Article
Full-text available
BACKGROUND Endometrial papillary serous carcinoma (EPSC) is a rare gynecological malignancy that often metastasizes before the presentation of symptoms or diagnosis of the primary disease. The most common locations of metastases for this malignancy are the lungs, liver, and bones. Metastases to the central nervous system (CNS) are rare. Solitary CN...
Article
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BACKGROUND Arteriovenous malformations (AVMs) are vascular malformations that are more commonly found intracranially, followed by the head, neck, limbs, and trunk. Extracranially, AVMs can mimic peripheral nerve tumors, leading to misdiagnosis. OBSERVATIONS A 19-year-old female, who presented with left lateral lower leg pain, was preoperatively th...
Article
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Hypertrophic Cardiomyopathy (HCM) is a common inherited disorder that can lead to heart failure and sudden cardiac death, characterized at the histological level by focal areas of myocyte disarray, hypertrophy and fibrosis, and only a few disease-targeted therapies exist. To identify the focal and spatially restricted alterations in the transcripti...
Article
Objectives: Excess pericardial adipose tissue (PAT) is associated with a higher risk of cardiovascular diseases. Currently, available methods for reducing PAT volume include weight loss through diet and exercise, weight loss with medications, and bariatric surgery. However, these methods are all limited by low patient compliance to maintain the re...
Preprint
Full-text available
Hypertrophic Cardiomyopathy (HCM) is a common inherited disorder that can lead to heart failure and sudden cardiac death, characterized at the histological level by focal areas of myocyte disarray, hypertrophy and fibrosis, and few disease-targeted therapies exist. To identify, focal, spatially restricted alterations in transcriptional pathways and...
Article
Full-text available
Eastern equine encephalitis virus (EEEV) is a relatively little-studied alphavirus that can cause devastating viral encephalitis, potentially leading to severe neurological sequelae or death. Although case numbers have historically been low, outbreaks have been increasing in frequency and scale since the 2000 s. It is critical to investigate EEEV e...
Article
Spinal stenosis is one of the most common neurosurgical diseases and a leading cause of pain and disability. Wild-type transthyretin amyloid (ATTRwt) has been found in the ligamentum flavum (LF) of a significant subset of spinal stenosis patients who undergo decompression surgery. Histologic and biochemical analyses of ligamentum flavum specimens f...
Article
Objectives: Viral infections of the central nervous system can be challenging to diagnose because of the wide range of causative agents and nonspecific histologic features. We sought to determine whether detection of double-stranded RNA (dsRNA), produced during active RNA and DNA viral infections, could be used to select cases for metagenomic next...
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Objectives There is growing evidence that excess adipose tissue within the head and neck contributes to obstructive sleep apnea (OSA), particularly in obese patients. This subset of the population is often difficult to treat with surgical therapies. We theorized that a novel, transcervical method of injectable cryoablation using ice‐slurry can achi...
Article
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OBJECTIVE Wild-type transthyretin amyloid (ATTRwt) is deposited in the ligamentum flavum (LF) of a subset of patients with spinal stenosis who undergo decompressive surgery, although its role in the pathophysiology of spinal stenosis is unknown. It has been theorized that degeneration of intervertebral discs causes increased mechanical stress and i...
Article
Background One key contributor to lumbar stenosis is thickening of the ligamentum flavum (LF), a process still poorly understood. Wild-type transthyretin amyloid (ATTRwt) has been found in the LF of patients undergoing decompression surgery, suggesting that amyloid may play a role. However, it is unclear whether within patients harboring ATTRwt, th...
Article
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OBJECTIVES/GOALS: Wild-type transthyretin amyloid (ATTRwt) deposits have been found to deposit in the ligamentum flavum (LF) of spinal stenosis patients prior to systemic and cardiac amyloidosis, and is implicated in LF hypertrophy. Currently, no precise method of quantifying amyloid deposits exists. Here, we present our machine learning quantifica...
Preprint
Full-text available
Background One key contributor to lumbar stenosis is thickening of the ligamentum flavum (LF), a process still poorly understood. Wild-type transthyretin amyloid (ATTRwt) has been found in the LF of patients undergoing decompression surgery, suggesting that amyloid may play a role. However, it is unclear whether within patients harboring ATTRwt, th...
Article
Full-text available
Wild-type transthyretin amyloidosis (ATTRwt) is an underdiagnosed and potentially fatal disease. Interestingly, ATTRwt deposits have been found to deposit in the ligamentum flavum (LF) of patients with lumbar spinal stenosis before the development of systemic and cardiac amyloidosis. In order to study this phenomenon and its possible relationship w...
Article
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Background Amyloidosis is a protein misfolding disorder that leads to the deposition of beta-pleated sheets of a fibrillar derivative of various protein precursors. Identification of the type of precursor protein is integral in treatment decision-making. The presence of two different types of amyloid in the same patient is unusually rare, and there...
Article
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• Congenital LVD is a rare cause of stroke in young patients. • LVD results from replacing myocardium with fibrous or muscular tissue. • Diverticulum and pseudoaneurysm are in the differential diagnosis of LV outpouching. • LVD forms a cavity that communicates with the LV through a short neck. • LVDs that result in thrombus formation and stroke sho...
Article
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Background Spine surgeons rarely consider metal allergies when placing hardware, as implants are thought to be inert. Case Description A 32-year-old male presented with a skin rash attributed to the trace metal in his spinal fusion instrumentation. Patch testing revealed sensitivities to cobalt, manganese, and chromium. He underwent hardware remov...
Preprint
Full-text available
Background: Wild-type transthyretin amyloidosis (ATTRwt) is an underdiagnosed and potentially fatal disease. Interestingly, ATTRwt deposits have been found to deposit in the ligamentum flavum (LF) of patients with lumbar spinal stenosis prior to the development of systemic and cardiac amyloidosis. In order to study this phenomenon and its possible...
Article
Full-text available
This morphological and immunohistochemical study demonstrates that tumors currently known as “middle ear adenomas” are truly well-differentiated epithelial neuroendocrine tumors (NETs) composed of cells comparable to normal intestinal L cells, and therefore, these tumors resemble hindgut NETs. These tumors show consistent expression of glucagon, pa...
Article
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BACKGROUND Primary meningeal melanocytic neoplasms are exceedingly rare tumors, representing only 0.06% to 0.1% of all primary brain tumors and ranging in spectrum from benign localized tumors to highly aggressive malignant lesions. The diagnosis of these tumors is often challenging from clinical, radiological, and pathologic standpoints. Equally c...
Article
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BACKGROUND Paragangliomas (PGLs) are rare neoplasms that may be associated with hereditary PGL syndromes and variable risk of metastasis. Middle ear adenomas are extremely rare tumors with no known hereditary predisposition and extremely low risk of metastasis. Although often easily differentiated, they may share clinical and pathological features...
Article
Age-related cardiac amyloidosis results from deposits of wild-type tranthyretin amyloid (ATTRwt) in cardiac tissue. ATTR may play a role in carpal tunnel syndrome (CTS) and in spinal stenosis (SS), indicating or presaging systemic amyloidosis. We investigated consecutive patients undergoing surgery for SS for ATTR deposition in the resected ligamen...
Article
Background Wild-type transthyretin (ATTRwt) amyloid deposition has been found in the ligamentum flavum (LF) of patients undergoing spinal stenosis surgery. Our group previously reported that ATTRwt amyloid is associated with an increased lumbar ligamentum flavum thickness at symptomatic levels that required surgery. A comprehensive evaluation of LF...
Article
Full-text available
Extradural atlantoaxial cysts are typically related to C1-2 degeneration. Intradural cysts may cause secondary syringobulbia depending on the size and cerebrospinal fluid flow obstruction. However, medullary syrinxes have not been previously described with extradural cysts. Treatment of symptomatic lesions involves surgical resection, often via a f...
Article
The term “giant cell myositis” has been used to refer to muscle diseases characterized histologically by multinucleated giant cells. Myasthenia gravis is an autoimmune neuromuscular junction disorder. The rare concurrence of giant cell myositis with myasthenia gravis has been reported; however, the clinical and histological features have varied wid...
Article
Background Wild-type transthyretin (ATTRwt) amyloid deposits have been found in the ligamentum flavum of patients undergoing surgery for spinal stenosis. The relationship between ATTRwt and ligamentum flavum thickness is unclear. We used pre-operative magnetic resonance imaging (MRI) to analyze ligamentum flavum thickness in lumbar spinal stenosis...
Article
The emergence and spread of SARS-CoV-2 has resulted in significant global morbidity, mortality, and societal disruption. A better understanding of virus-host interactions may potentiate therapeutic insights toward limiting this infection. Here, we investigated the dynamics of the systemic response to SARS-CoV-2 in hamsters by histological analysis...
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A patient with a prior history of intradural schwannoma and disc herniation presented with radicular pain after being hit in the thigh by a dog's tail. She was worked up and found to have a tumor of her right sciatic nerve. The tumor was resected and histology was consistent with schwannoma. The dog's tail acted as a Tinel's sign maneuver and led t...
Article
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A man with a presumed diagnosis of hypertrophic cardiomyopathy presented after a ventricular fibrillation arrest. Review of prior cardiac magnetic resonance imaging revealed a pattern of late gadolinium enhancement that was atypical for hypertrophic cardiomyopathy and most consistent with cardiac sarcoidosis, with diagnosis confirmed by endomyocard...
Article
Background Wild-type transthyretin amyloid (ATTRwt) has been noted to deposit in the ligamentum flavum of the spine. Prior studies have focused on ATTRwt in the lumbar region, but there is a lack of studies discussing its presentation in other levels of the spine. We report on the presentation of patients with confirmed amyloid in the cervicothorac...
Article
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Introduction: Lymphocytic hypophysitis often presents with headache, hypopituitarism and visual disturbance, the latter from optic nerve compression. Rarely, it can present with diplopia from cranial nerves III, IV and VI (3.7%) and cavernous sinus involvement (1). Clinical Case: A 40 year old woman presented with left eye pain, blurry vision, ptos...
Article
A unique clinical circumstance involving middle-aged male identical twins with obstructive hypertrophic cardiomyopathy (HC) is reported. The concordance of morphologic (i.e., phenotype) findings and clinical course between the 2 patients is remarkable, including timing of the onset and progression of heart failure due to left ventricular outflow tr...
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Introduction Teratomas of the head and neck region are rare lesions, representing just 5% of all congenital teratomas. Usually found in the pineal region orneurohypophysis, teratomas are uncommonly located in the posterior occiput. Case Presentation Herein, we present a case of a female neonate born at 37-week gestation with hydrocephalus, an occi...
Article
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Dynamic alterations in the unique brain extracellular matrix (ECM) are involved in malignant brain tumors. Yet studies of brain ECM roles in tumor cell behavior have been difficult due to lack of access to the human brain. We present a tunable 3D bioengineered brain tissue platform by integrating microenvironmental cues of native brain-derived ECMs...
Article
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Background : Very late antibody-mediated rejection (AMR) in heart transplant patients (over 10 years post-transplant) is very rare. It is associated with high mortality, graft dysfunction, and fulminant coronary artery vasculopathy (CAV) and should remain in the differential for patients presenting with late graft dysfunction. Case summary : A 5...
Article
Background: Transthyretin wild-type (ATTRwt) amyloidosis is a systemic process resulting in deposition of misfolded transthyretin protein in several different tissues throughout the body. It is known to be a cause of progressive, life-threatening cardiomyopathy and lumbar spinal stenosis and carpal tunnel syndrome. Case description: Here we pres...
Chapter
Although descriptions of the pituitary gland can be traced to the second century A.D., major advances continue to be made with respect to elucidating the organization and functional anatomy of this organ system. On the surface, the pituitary gland would appear to be a rather simple structure, containing two lobes (anterior and posterior) that are w...
Article
Background: Intracranial metastasis is a common complication of systemic malignancy. A rare subset of intracranial masses constitutes tumor-to-tumor metastasis, in which an extracranial neoplasm hematogenously spreads to an existing intracranial lesion. Case description: Here we present the unique case of a 59-year-old man with known hepatocellu...
Article
Childhood cancer survivors are at risk for ongoing health risks related to their initial treatment. One potential long-term complication following radiation is the development of secondary tumors, including peripheral nerve tumors, such as schwannomas. We present three adolescent and young adult (AYA)-aged survivors of pediatric cancer (22-40 years...
Article
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Objective Solitary fibrous tumors (SFT) and hemangiopericytomas (HPC) are now classified along a single spectrum of fibroblastic mesenchymal tumors with NAB2–STAT6 fusion. This fusion acts as a driver mutation that constitutively activates EGR1, which is known to be involved in the p16 pathway. Overexpression of p16 is associated with malignancy an...
Article
Hypertrophic cardiomyopathy (HC) has historically been characterized as a disease of substantial left ventricular hypertrophy, often associated with dynamic left ventricular outflow tract obstruction. However, we have recently encountered patients with subaortic obstruction and only minimal basal septal thickness, raising important management impli...
Article
Background and importance: Malignant peripheral nerve sheath tumors (MPNST) are relatively rare tumors of peripheral nerves that are notable for their locally aggressive nature, ability to metastasize, poor prognosis, and association with Neurofibromatosis type I. We present the case of a patient with a trigeminal nerve MPNST who developed an unus...
Article
Mucorales organisms are an uncommon cause of invasive fungal infections after solid organ transplantation but are associated with great morbidity and mortality. We report a fatal case of disseminated Cunninghamella infection early after heart transplantation. The patient developed graft dysfunction and elevated markers of myocyte injury and autopsy...
Article
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Ependymomas are common spinal lesions, with the vast majority arising in an intramedullary location. Several cases have been described in the literature of ependymomas in an intradural, extramedullary location. The authors present a case of a 56-year-old female who presented with several weeks of lower back pain and weakness. MRI revealed an intrad...
Article
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Research has exposed cancer to be a heterogeneous disease with a high degree of inter-tumoral and intra-tumoral variability. Individual tumors have unique profiles, and these molecular signatures make the use of traditional histology-based treatments problematic. The conventional diagnostic categories, while necessary for care, thwart the use of mo...
Article
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Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease rarely occurs in the posterior aspect of the craniocervical junction (CCJ). To the best of our knowledge, there have been only 2 previously reported cases of patients with posterior CPPD lesions in this region that have led to cervical myelopathy. We report the case of a 70-year-old...
Article
Background: The Cox maze IV operation has become the preferred surgical treatment for atrial fibrillation, as it is associated with less morbidity and complexity than the Cox maze III procedure, yet is still highly effective. Numerous studies have been conducted in animals to examine the histopathology of this operation on the heart but studies on...
Article
INTRODUCTION: PSCM is exceedingly rare, comprising 1% of all melanomas. Unlike their cutaneous counterparts; the origin and clinical characteristics of these malignancies is poorly characterized. Mutations in GNAQ have been implicated in non-cutaneous melanocytic tumors. We present a case of PSCM and review the literature, with a focus on intramedu...
Article
The oncogene Astrocyte Elevated Gene-1 (AEG-1) is overexpressed in a wide variety of human cancers. In vitro and in vivo nude mouse xenograft studies have established the tumor-promoting role of AEG-1. Activation of multiple signaling pathways, such as NF-κB, PI3K/Akt, Wnt/β-catenin and MEK/ERK, has been attributed to mediate oncogenesis by AEG-1....

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