Pseudotumor Cerebri Secondary to Jugular Bulb Thrombosis: A Case Report and a Review of the Diagnostic Steps.

Pseudotumor cerebri (PTC) secondary to cerebral venous sinus thrombosis can be a difficult diagnosis to make for various reasons, including an atypical patient profile and potentially pleomorphic signs and symptoms. The symptoms can be insidious and can evolve acutely, subacutely, or chronically. To complicate the picture even further, neurodiagnostic testing can be particularly troublesome due to both false-positive and false-negative results. Frequently, multiple imaging modalities are variably deployed, and they include computed tomography (CT) with and without contrast, computed tomography venogram (CTV), magnetic resonance imaging (MRI), and magnetic resonance venography (MRV) of the brain. The thrombus can be quite subtle, requiring the seasoned eye of an experienced neuroradiologist. Nevertheless, when a diagnosis is made, the treatment can be highly efficacious and gratifying as it can prevent serious visual complications. We present a rare case of PTC due to a jugular bulb thrombosis and outline the challenging diagnostic steps.

A Case Report of Diabetic Striatopathy: An Approach to Diagnosis Based on Clinical and Radiological Findings.

Diabetic striatopathy (DS) is an acute hyperkinetic movement disorder characterized by hemiballismus-hemichorea (HBHC) due to nonketotic hyperglycemia. DS manifests a fascinating interplay between endocrinopathy (diabetes), striatal (putamen, caudate nucleus, globus pallidus) pathology, and a dramatic neurological movement disorder, HBHC. The striking hyperintensity on imaging modalities such as computed axial tomography (CT) scan of the brain and T1-weighted magnetic resonance imaging (MRI) of the brain can mislead the clinician to an erroneous diagnosis of a cerebral hemorrhage and/or ischemic infarct, especially in an acute setting. We present an acute case of DS and outline the natural history, semiology, typical radiological findings, and therapeutic options. With careful and thoughtful analysis, an accurate diagnosis can be exacted, sparing the patient unnecessary anxiety and medical costs.

A Case of Secondary Trigeminal Neuropathy Due to Local Malignant Invasion of the Maxillary and Mandibular Nerves at the Skull Base: A Case Report With Review of Differential Diagnosis.

Trigeminal neuropathies (TNp) are a group of well-characterized disorders that involve damage to or infiltration of the trigeminal nerve. The underlying etiology of trigeminal neuropathy can be traumatic, inflammatory, autoimmune, paraneoplastic, malignant, and very rarely infectious. We present a case of trigeminal neuropathy due to local malignant invasion of the mandibular nerve with mandibular nerve enhancement at the foramen ovale and foramen rotundum. In the process, we review various etiologies of trigeminal neuropathy associated with trigeminal nerve involvement at the foramina. We emphasize the importance of a comprehensive evaluation in patients with trigeminal neuropathy, which includes searching for perineural spread or invasion by a local head and neck malignancy, as well as ruling out an inflammatory or autoimmune etiology. Our case also demonstrates that a higher field strength magnet can reveal pathology unseen with a lower field strength magnet.

Paroxysmal Non-Kinesigenic Choreoathetosis Case Report and a Review of the Pathogenesis.

Paroxysmal dyskinesias are a rare group of episodic movement disorders characterized by any combination of dystonia, chorea, and athetosis. Patients usually present early in life with episodes of variable frequency involving the limbs or facial muscles that can be disabling. In this article, we present a case of paroxysmal non-kinesigenic dyskinesia that was responsive to the sodium-channel blocker carbamazepine. Recent data has revealed the role of voltage-gated sodium channels in the pathophysiology of the disease; hence, these disorders are referred to as channelopathies. Further advancements in genetic analysis have elucidated targets corresponding to these disorders, indicating a possible role for gene sequencing in helping to differentiate the subtypes of paroxysmal dyskinesias. This case report sheds light on the pathophysiology of the various channelopathies, especially the findings of cerebellar spreading depolarization and its implication in paroxysmal kinesigenic and non-kinesigenic dyskinesias.

A Case of Sjögren's Syndrome Associated With Trigeminal Neuropathy and Enhancement of the Mandibular Nerve at the Foramen Ovale: A Case Report and a Review of the Differential Diagnosis and Mechanisms of the Disease.

We describe a case of Sjögren's syndrome-associated trigeminal neuropathy with mandibular nerve enhancement at the foramen ovale and Gasserian ganglion (Meckel's cave) in a patient with a prior history of breast cancer. We also explore the differential diagnosis of trigeminal neuropathy associated with mandibular nerve involvement at the foramen ovale and exclude other diseases such as Sjögren's syndrome or perineurial invasion as a result of various carcinomas. We emphasize the importance of an investigative triad of searching for a local head-and-neck malignancy that may metastasize by perineural spread or invasion, excluding a distant malignancy or paraneoplastic phenomenon and ruling out an autoimmune etiology such as Sjögren's syndrome. In the process, we briefly outline the basic immunopathologic processes.

Seropositive Muscle-Specific Tyrosine Kinase Myasthenia Gravis Presenting as a Late-Onset Isolated Sixth Nerve Palsy: A Case Report and a Brief Review of Subtypes of Myasthenia Gravis.

Autoimmune myasthenia gravis (MG) is a well-characterized post-synaptic disorder of neuromuscular transmission. Immunologically, there is complement activation with autoantibodies binding to the acetylcholine receptor (AChR), leading to cross-linking and internalization of the receptor. The diminished functional clustering leads to impaired folding of the post-synaptic membrane. The antibodies generated by the autoimmune process are directed at the various components of the post-synaptic membrane and its scaffolding, including the AChR, muscle-specific tyrosine kinase (MuSK), low-density lipoprotein receptor-related protein 4 (LRP4), and the other recently described epitopes including the extracellular membrane proteins agrin and collagen Q (ColQ). MuSK MG is phenotypically different from classic AChR-antibody-mediated MG by a more frequent presentation of bulbar weakness, less responsiveness to symptomatic therapy with acetylcholinesterase inhibitors, the absence of a thymoma, and a better therapeutic response to a cluster of differentiation (CD-20) B-cell therapy such as rituximab. The pleiotropic ocular findings of ocular MG include ptosis, fluctuating and variable involvement of cranial nerves III, IV, and VI, pseudo-internuclear ophthalmoplegia (INO), near-complete or complete ophthalmoplegia, and variable gaze palsies. To our knowledge, we present one of the very few reported cases of MuSK MG presenting as isolated sixth nerve palsy. The localization of a sixth nerve palsy with lateral rectus muscle weakness can be due to disease anywhere along its path from the abducens nucleus, coursing at the skull base through Dorello's canal, through the cavernous sinus, and along its path through the superior orbital fissure and into the orbits. A painless sixth nerve palsy should alert the clinician to MuSK-MG as we outline in this case report.

Malignant lymphomatous invasion of Meckel's cave: pathoanatomical considerations of the petrous apex.

Secondary central nervous system lymphoma is rare, occurring in up to 10% of non-Hodgkin's lymphoma patients and in 5% of diffuse large B-cell lymphoma patients. The prognosis is poor, even rarer is metastasis of large B-cell lymphomas into Meckel's cave and the trigeminal nerve roots. We describe a relapsing case of a large B-cell lymphoma that migrated into Meckel's cave, the mandibular branch of the trigeminal nerve and the adjacent cavernous sinus. We review petrous apex anatomy, review the literature of metastatic spread into Meckel's cave and analyse existing pathoanatomical studies that explain the conduits and barriers of tumour spread. Understanding this pathoanatomical relationship is critical for neurologists and neurosurgeons alike to effectively correlate patient signs and symptoms to intracranial pathology and identify origins and sites of metastatic dispersion in similar rare clinical scenarios.

Myeloneuropathy in the Setting of Hypocupremia: An Overview of Copper-Related Pathophysiology.

A posterior cord or dorsal column myelopathy due to neurosyphilis presenting as a tabetic gait is a classic neurological vignette and is taught to all medical students. Its clinical presentation is so graphic that its simulacrum with diseases other than neurosyphilis is labeled as pseudotabes. The latter can be seen with vitamin B12 deficiency as a subacute combined degeneration (SCD) of the spinal cord, another neurology classic. However, not all cases of pseudotabes are due to posterior cord myelopathy as some can arise with other deafferentation syndromes such as polyganglioneuropathies as seen with paraneoplastic syndromes, Sjogren's syndrome, idiopathic autoimmune diseases, and post-viral neuronopathies. A unique and interesting cause of pseudotabes is due to copper deficiency; copper being a metallic trace element that is fundamental to cellular life. Herein, we present a case of copper deficiency manifesting as pseudotabes and review the biochemical properties of copper and its effects on the nervous system.

Recurrent Amaurosis Fugax Secondary to Tolosa-Hunt Syndrome: A Case Report and Review of Phenotypes and Pathology.

Tolosa-Hunt syndrome (THS) is a fascinating condition that is ipso facto a cavernous sinus syndome. As such it is associated with inflammation of the cavernous sinus walls and contents with spread to contiguous structures such as the orbital apex and superior orbital fissure. Therefore it does not come as a surprise that there is overlap with the condition of orbital pseudotumor. Furthermore, the typical presentation of THS involves variable affliction of the contents of the cavernous sinus with ocular and facial pain, ophthalmoplegia, facial numbness and Horner syndrome. To our knowledge, we present one of the only reported cases of recurrent amaurosis fugax and transient visual obscurations secondary to THS. Despite being an odd-ball presentation, these manifestations make intuitive sense as we demonstrate luminal narrowing of the right carotid siphon in the setting of cavernous wall enhancement, peri-arteritis of the carotid siphon being well-documented pathologically in the literature. The basis for the transient visual obscurations is more speculative but worthy of further study.

Isolated Double-Positive Optic Neuritis: A Case of Aquaporin-4 and Myelin Oligodendrocyte Glycoprotein Antibody Seropositivity.

Optic neuritis (ON) causes acute vision loss with typical and atypical profiles, serological markers, imaging findings, and clinical outcomes depending on the associated underlying pathophysiology. Neuromyelitis optica (NMO) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD) are the usual causes of acute severe sequential or simultaneous bilateral optic neuritis. These conditions are usually accompanied by multi-level spinal cord demyelination, and notably, they are typically positive for either NMO or Myelin oligodendrocyte glycoprotein (MOG) autoantibodies, but rarely both. We present a case of isolated sequential bilateral optic neuritis that was seropositive for both NMO and MOG antibodies.

Isolated Sixth Nerve Palsy: A Case of Pseudotumor Cerebri and an Overview of the Evolutionary Dynamic Geometry of Dorello's Canal.

The dynamics of increased intracranial pressure (ICP) and sixth cranial nerve palsy has undergone a paradigm shift, with emphasis shifting from a length hypothesis to a theory based on novel anatomic findings pertaining to the geometry of Dorello's canal. In particular, the sixth cranial nerve resides in a transfixed coaxial cylinder within the canal. The cisternal portion of the nerve is intradural and the rest of the nerve is extradural; therefore, with increased ICP, the former is stretched, thereby pulling on the rest of the nerve, which is anchored in Dorello's canal. We present a case of pseudotumor cerebri secondary to minocycline presenting with an isolated sixth nerve palsy. This case is used as a platform to segue into the recent findings outlined above, in particular, the evolutionary transformation of Dorello's canal from a circular outline with a bony roof to an elliptic profile with a fibro-osseus roof during hominid basocranial expansion. The fibro-osseus roof, being elastic, is particularly susceptible to the influence of raised ICP, thereby narrowing the canal and injuring the sixth cranial nerve.

Magnetic Resonance Neurography (MRN) of the Brachial Plexus: A Case of Parsonage Turner Syndrome and a Basic Review of Imaging of the Brachial Plexus.

The Parsonage-Turner syndrome (PTS) or immune-mediated brachial plexopathy is a monophasic illness with well-described semiology and reasonable insights into pathogenesis. With the advent of spectacular advancements in magnetic resonance imaging (MRI) technology directed at shortening the T2 echo times and annihilating the "magic angle" and with short tau inversion recovery (STIR) sequences, we now have a new window into the evolution of inflammatory changes involving the nerve roots, brachial plexus and the peripheral nerves in inflammatory diseases of the nerves. Not only can these imaging modalities exclude other structural pathologies but they can also localise disease of the brachial plexus and outline the extent of disease and so allow the clinician to explore the natural history of immune-mediated brachial plexopathies. Indeed, these imaging sequences can antedate electromyographic findings and they can determine the effects of chronic denervation of muscle and fatty replacement. We present one such case of the PTS in order to demonstrate the power of these imaging modalities. In so doing, we outline some of the very basic correlations between the physics of MRI and pathology of the brachial plexus. An unexpected finding in this case report is the dramatic resolution of power loss following immunotherapy in our patient who had positive image findings on T2-weighted sequences and STIR imaging and who otherwise has had a static course. The implications of these findings are explored and adumbrated on.

Steroid-Resistant Double-Seronegative Optic Neuritis Responds Favorably to Plasma Exchange.

The clinical presentation of optic neuritis is quite characteristic, and the epidemiology, differential diagnosis, and treatment protocol are well established. However, when the presentation of optic neuritis is atypical, bilateral, and intravenous steroid-resistant, the treatment guidelines are quite nebulous. We present a case of bilateral severe double-seronegative optic neuritis with catastrophic vision loss and intravenous steroid resistance. After an exhaustive investigation, we empirically treated our patient with plasma exchange therapy and obtained a dramatic recovery of vision. When an immune etiology is suspected, this case is instructive vis-a-vis the utility of plasma exchange in refractory cases of optic neuritis despite seronegativity.

Pseudo-Anterior Interosseus Nerve Syndrome: A Case Report and a Review of Clinical Signs, Pathology and Functional Anatomy of the Precision Grip.

Precision grip, a prehensile function of humans, is exacted through the action of the median nerve and its main tributary, the anterior interosseus nerve (AIN). In the forearm, the AIN can be subject to nerve entrapment by tendinous and fibrous arches or accessory and variant muscles. It is also vulnerable to trauma of the upper arm and forearm. To the neurologist, an isolated neuritis or an immune-mediated medial cord or lower trunk brachial plexopathy (Parsonage-Turner syndrome) is the usual mode of presentation. When the spread of muscle weakness is beyond the territory of the AIN, the syndrome is referred to as a pseudo-AIN. The AIN is grouped into fascicles that are compartmentalized separately from the median nerve proper, and trauma in the upper arm may selectively involve the AIN. We present a case of pseudo-AIN following elbow arthroscopic surgery and outline the pathology, clinical signs, and functional anatomy of the AIN and the precision grip.

Migraine Triggers: An Overview of the Pharmacology, Biochemistry, Atmospherics, and Their Effects on Neural Networks.

We define a migraine trigger to be an endogenous agent or agency such as the menses or an exogenous agent or agency such as red wine or a drop in barometric pressure, and their ability to reduce the threshold of a migraine attack in those predisposed to migraine. This definition excludes agents with idiosyncratic mechanisms that may trigger a migrainous (migraine-like) headache in non-migraineurs such as benign cough headaches or headaches due to altitude-sickness. We also assume as axiomatic that migraine has as its basis the activation of the trigeminovascular pathway (TVP) and the key role of serotonin and the calcitonin gene-related peptide (CGRP). The network activation of the visual/auditory association cortices and the rostrodorsal pons (locus ceruleus and raphe nucleus) are also accepted as key features of activation of the TVP. In addition, we outline the role of the superior salivatory nucleus-sphenopalatine ganglion-greater superficial petrosal nerve (SSN-SPG-GSPN) arc in migraine activation. We also explore how olfactory afferents intermingle with trigeminal nerve collaterals in the glomeruli of the olfactory bulb thus allowing volatile molecules to activate the TVP and induce a migraine. The classification of migraine triggers is complex, as there is a wide panorama of inciting agents, including atmospheric conditions, a wide-ranging variety of foods and beverages, endogenous hormonal influences, synthetic alkaloids and dyes, and volatile molecules (odorants). We will explore the high-frequency migraine-provoking agents in each category. There are exciting and intriguing hypotheses regarding the role of atmospheric chemistry when the barometric pressure drops; the role of hot, dry desert winds and lightning discharges in the generation of cations and the turnover of serotonin in the nervous system. We will explore the effects of a drop in barometric pressure on the vestibular nuclei and the modulation of sympathetically mediated pain. The role of volatile odorants and their activation of the transient receptor potential ankyrin-1 (TRPA-1) receptor will be outlined. We will streamline the highly complex role of estrogen fluctuation in the precipitation of migraine headaches, its pharmacodynamic effects, and the role of the sexually dimorphic nucleus of the preoptic area (SDN-POA) of the hypothalamus. We will also adumbrate the protean effects of alcohol and its congeners and the role of stress and sleep disturbances in the allostatic load model of salience network-pain perception.

"Person-in-the-Barrel" Syndrome: A Case Report of Bilateral Arm Paresis Due to Vasculitis With a Review of Pathological Mechanisms.

"Person-in-the-barrel" syndrome is a descriptive term for bilateral arm (brachial) paresis in the absence of lower extremity (crural) weakness or bulbar (medullary) weakness. This phenomenon is associated with various descriptive terms such as "distal field infarction", "flail limbs", and "cruciate paralysis". Arriving at a specific diagnosis is a fascinating exercise in anatomical localization. Strategic lesions involving the watershed zones of the motor frontal lobes and the pyramidal decussation at the cervico-medullary junction are the classic sites of injury. However, peripheral causes such as motor neuron disease, mononeuritis multiplex (vasculitis), bilateral brachial plexopathy, and critical illness myopathy have been sporadically reported and can stochastically inflict the motor nerves or muscles of the upper extremities. In this report, we present a case of vasculitis with weakness restricted to the upper extremities and also delve into the neuropathological mechanisms of "person-in-the-barrel" syndrome.

Hypnic Headache Responds to Topiramate: A Case Report and a Review of Mechanisms of Action of Therapeutic Agents.

Hypnic headaches are unique as they are exclusively nocturnal, occurring in rapid-eye movement (REM) and non-REM sleep. Their nocturnal nature suggests a role for cyclic mechanisms involving the hypothalamus despite conflicting imaging results for the role of the posterior hypothalamus. Nevertheless, pharmacological therapeutics acting as highly effective agents, such as caffeine and melatonin, can modulate the sleep-wake cycle. In addition, indole agents such as indomethacin that are anti-nociceptive and affect cerebral blood flow also prove to be efficacious. Gabanoids and topiramate also have reported efficacy. We report the case of a topiramate-responsive hypnic headache patient and outline in detail the potential mechanisms of topiramate and the other therapeutic agents and adumbrate on the neuronal networks of migraine, the trigeminal autonomic cephalgias and suggest a potential neural circuit for hypnic headaches.

Apathy Antedating and Evolving With Dementia: A Case Report and Insights Into Apathy as a Network Dysfunction.

Apathy is a motivational disorder characterized by a lack of drive or indifference to salient endogenous or exogenous influences or stimuli. In the classical literature, it was referred to as a lack of mental energy or vitality and attributed to dysfunction of the ergotropic sympathetic pathway involving the posterior hypothalamus, thalamus, cingulate cortex, and hippocampal formation. Recent advanced imaging studies have expanded the ambit of network dysfunction to include the dopaminergic mesolimbic system and the salience network that gauges the valence or energy of the mesolimbic system. The classic Papez circuit also has a role in the pathogenesis of apathy. In order to understand the mechanisms of apathy seen with a wide range of diseases including neurodegenerative disorders, trauma, and strokes, one needs to think of apathy as a network disorder. In this report, we present a case of apathy antedating and evolving with Alzheimer's disease and delve into the network theory of apathy and explore potential pharmacological therapies.

Space Flight-Associated Neuroocular Syndrome, Idiopathic Intracranial Hypertension, and Pseudotumor Cerebri: Phenotypic Descriptions, Pathogenesis, and Hydrodynamics.

Recent data from astronauts who have returned to Earth from a long-duration space flight have unequivocally distinguished spaceflight-associated neuro-ocular syndrome (SANS) from idiopathic intracranial hypertension (IIH) and pseudotumor cerebri (PTC). We review the semiology and pathogenesis of these three entities, noting that optic disc edema is what unites them, and this where the similarities between SANS and IIH/PTC end. We distinguish between PTC and IIH and between SANS and IIH/PTC and review the medical and surgical therapy of IIH/PTC. The key to understanding the phenomenon of optic disc edema is the geometry of the optic nerve sheath, which is a simulacrum of an inverted Venturi tube. This allows us to theoretically study the hydrodynamics of the optic nerve sheath by applying simple physical laws, including the Venturi effect, Poiseuille's law, and Reynold's number, and we speculate on nature's design and the correlation of form and function in understanding how cerebrospinal fluid (CSF) circulates in the optic nerve sheath as it approaches the optic nerve head. Recent spectacular data on the histology of the blood nerve-barrier of the optic nerve disc and the glymphatic system of the optic nerve sheath will also help us understand the development of optic disc edema due to the microgravity-induced cephalad shift of CSF in SANS. We will explore the role of the sodium/potassium adenosine triphosphatase (ATPase) pump on choroid plexus epithelial cells and the aquaporin-4 water receptors located on astrocyte end-feet and their complex interactions with the tetracyclines, mineralocorticoids, and therapeutic agents with carbonic anhydrase activity. We also adumbrate the complex interactions between obesity, vitamin A, and 11-beta-hydroxysteroid dehydrogenase and how the aquaporin-4 receptor relates to these interactions.

Meralgia Paresthetica: A Case Report With an Update on Anatomy, Pathology, and Therapy.

Meralgia paresthetica, a condition characterized by tingling, numbness, and burning pain in the lateral aspect of the thigh, is caused by compression of the lateral femoral cutaneous nerve. The incidence of meralgia paresthetica increases with obesity and diabetes. The unique anatomy of the nerve that tunnels through the inguinal ligament predisposes it to inflammation, trauma, and entrapment. The pathology of meralgia paresthetica parallels that of entrapment neuropathies but with additional inflammatory overlay in certain instances. The clinical diagnosis is relatively simple due to its unique clinical features. The prognosis is generally excellent, and the treatment is straightforward that includes peripheral nerve blocks, neurectomy, nerve decompression, and pulsed radiofrequency neuromodulation. This current case of meralgia paresthetica highlights the salient clinical symptoms and signs. We have also described the electrophysiological studies of the lateral femoral cutaneous nerve, its anatomical variations, and the associations of meralgia paresthetica with bariatric surgery, critical care patients, tight clothing, pregnancy, and posterior spine surgery. We have also outlined the current treatment strategies.