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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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. 

"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.

The "Dangles" - Wrist, Finger and Thumb Drop: A Case Report of Saturday Night Palsy and a Historical and Molecular Detour

Saturday night palsy refers to neuropraxia of the radial nerve following prolonged compression against the spiral groove of the humerus. The pattern of weakness is unique with wrist, thumb, and finger drop, and recovery is universal by six months. What makes this clinical entity fascinating are the toxic and metabolic diseases that can manifest similarly, namely, plumbism (Saturnism) and acute porphyrias. The acute porphyrias (heme biosynthetic inborn errors of metabolism) are well known to cause motor neuropathy, with upper more than lower limb weakness, with wrist, thumb and finger drop a frequent manifestation. Intriguingly, lead neurotoxicity (plumbism), which has historically been tightly associated with wrist, thumb, and finger drop, is associated with the inhibition of at least three enzymes of heme biosynthesis. Mechanistically, interference with heme ring synthesis interferes with electron transport chain protein synthesis, which leads to oxidative phosphorylation defects, energy failure, axonal transport impairment, and, subsequently, an axonopathy. The lead atom has a valence of two (giving up two electrons) similar to that of the calcium atom, allowing lead to bind to spongy and cortical bone and interfering with the presynaptic voltage-gated calcium channel (VGCC) neurons. We list the salient features and similarities of these two very rare entities, hence, the term plumboporphyric neuropathy for one of the genetic variants of heme biosynthesis. Lastly, we briefly outline the spectacular history of plumbism and adumbrate on the similarity of the bacchanalian ecstasy of Roman festivals (Saturnism), over-indulgence in lead-sweetened and lead-laden barrels of wine, and the syncretism between the Saturnine palsy and Saturday night palsy. We present a case of wrist, thumb, and finger drop due to compressive neuropraxia as a platform to segue into the historical simulacra.

Anisotropy of the Drawing Plane in Focal Hand Dystonia: A Case Report and a Novel Postulate of Dysfunctional Tensorial Networks

The pathophysiology of the dystonias has been associated with loss of inhibition in the sensory-motor cortex, brainstem and spinal cord, abnormal motor preparation in the pre-motor cortex, abnormal sensory processing in the sensory cortex, maladaptive plasticity and abnormal sensory-motor integration in the cerebral cortex. We present a case of focal hand dystonia with variance of spiral drawing in the horizontal and vertical planes, that is amelioration of spiral drawing in the vertical plane compared to the horizontal plane. We refer to this phenomenon as "anisotropy". We seize upon this unique finding and postulate a novel mechanism for the generation of the dystonias. The anisotropy referred to can only be explained by a breakdown of the tensorial transformation of a covariant vector to a contravariant vector in the frequency hyperspace of the brain. This novel hypothesis is based on the unequivocal invariance of tensorial transformation, a mathematical fact in differential geometry, the very geometry of the most celebrated and sublime General Theory of Relativity, and the model of dynamic brain function proposed by Pellionisz and Llinas.

Death and Rebirth of the Thalidomide Molecule: A Case of Thalidomide-Induced Sensory Neuropathy

The thalidomide molecule is a remarkable molecule that exists in a racemic mixture of optical isomers. In the 1950s, due to its teratogenicity, the levorotatory isomer led to its dramatic downfall. However, the molecule with its panoramic mechanisms of action and its uncanny ability to intercalate within the geometry of deoxyribonucleic acid (DNA), led to its remarkable renaissance; thalidomide being United States Food and Drug Administration (FDA)-approved for at least 13 different indications ranging from multiple myeloma to leprosy to glioblastoma. Thalidomide-induced polyneuropathy is usually reversible and is the rate-limiting step in its long-term use. The development of a polyneuropathy is invariably associated with a cumulative dose exceeding 20 grams. However, the polyneuropathy is almost always a sensory neuropathy. Asymmetry, bona fide weakness such as difficulty standing on the heels, a poly-ganglioneuropathy pattern with widespread or patchy numbness and sensory ataxia should raise a red flag and an alternative diagnosis should be considered. We present a typical case of a thalidomide-induced sensory neuropathy in order to highlight the resurgence of thalidomide use in clinical practice. We review the literature and outline the molecular biology of the thalidomide molecule.

A Novel Case of Cerebral Diplopia Secondary to a Posterior Parietal Cortex Ischemic Infarct: Proposal of a Mechanism of Generation of Polyopia Due to Convergence Insufficiency

All reported cases of cerebral polyopia in the literature are associated solely with occipital lobe disease, as seen with ischemic infarcts, migraine, trauma, and epilepsy. To our knowledge, this is the first case of polyopia associated with posterior parietal cortex (PPC) ischemic infarct to be reported in the literature. Previous hypotheses about mechanisms of polyopia have included cortical spreading depression, the vague idea of abnormal visual synthesis, and the holographic or holonomic brain theory. We propose a new mechanism due to dysfunction of the network from the PPC \begin{document}\rightarrow\end{document} frontal eye field (FEF) \begin{document}\rightarrow\end{document} paramedian midbrain and pontine reticular formation leading to convergence insufficiency, which leads to horizontal diplopia. The evidence ranging from tracer studies in macaque monkeys to functional MRI (fMRI) studies in patients with convergence insufficiency is presented to bolster our hypothesis. In the process, we also briefly review the neural pathways of convergence.

Delusional Infestation Secondary to the Dopamine Agonist Ropirinole in a Patient With Parkinson's Disease: A Case Report With an Outline of the Biology of Psychosis

Delusional infestation (DI) is a thought disorder, a delusion that one is infested with pathogens. Remarkably, these patients do not typically exhibit symptoms of anxiety or depression. The role of the dopamine D2 receptor is central to the idea of psychosis. In this article, we present a case of ropirinole-induced delusional skin infestation in a patient with Parkinson's disease, that was reversible with drug discontinuation. We seize upon this opportunity to discuss the pathology of the dopamine receptors, the glutamate N-methyl D-aspartate (NMDA) receptors and the serotonin 5-hydroxytryptamine (5HT-2A) receptors in the generation of psychosis. We outline the fundamental pharmacodynamical differences between the typical and atypical anti-psychotics that will help us understand how these agents work favorably and adversely. We also briefly review the neuroradialogy of psychosis and adumbrate on the mismatch between the meso-limbic system (motivational) and the salience network (valence) as the driver of the psychotic phenomenon.

The "Texas Longhorn" Syndrome: A Case of Posterior Interosseous Nerve Palsy With Noteworthy Observations

The posterior interosseous nerve (PIN) is quite a fascinating nerve. It wraps around the radial neck akin to the fibular nerve wrapping around the fibular neck. It can be compressed by the arcade of Frohse in a fashion similar to median nerve entrapment by the carpal tunnel. Furthermore, it divides into a number of branches, a simulacrum of the cauda equina, as it emerges from the supinator muscle. It is also associated with space-occupying pathologies; lipomas, and ganglion cysts being among the most common. It also has other interesting anatomical properties, such as fascicular compartmentalization, explaining PIN paralysis with radial nerve injuries. Finally, PIN lesions can lead to partial paralysis of finger extensors leading to the "Texas longhorn" hand gesture. We seize upon a case of PIN entrapment by fibrous adhesions and the arcade of Frohse, and explore the functional anatomy of the PIN.

Difficulty Standing on the Tiptoes? Think of an Epiconus Syndrome: A Case Report and a Review of the Pathobiology of the Conus and Epiconus

The motor deficits, urogenital dysfunction and perineal numbness of the conus medullaris syndrome are well known. Less well known is the disease of the epiconus, the spinal cord immediately above the conus medullaris. The disease is quite unique with ankle plantar-flexion weakness that usually exceeds ankle dorsi-flexion weakness. The epiconus syndrome can present with both upper and lower motor neuron findings and manifest unique findings on nerve conduction/electromyography studies. Intriguingly, lumbo-sacral corticospinal tract disease can involve trans-synaptic degeneration of the anterior horn motor neurons and lead to acute denervation, as recorded with electromyography. The conus medullaris also contains Onuf’s nucleus, which controls penile erection, ejaculation, the external urethral and the external anal sphincter and is the basis of the bulbo-cavernosus reflex. Extension of a lesion from the epiconus to the conus can lead to urogenital dysfunction. We seize upon a case of an epiconus syndrome in order to outline some of these fascinating observations including the pathobiology of the conus and epiconus. In order to understand the epiconus, one must be versed with the conus medullaris.

COVID-19-Induced Ischemic Infarcts With Normal Coagulation Profile and Excellent Outcome: A Case Report With Highlights on the Thrombotic Diathesis, Recent Transcranial Doppler Findings, and Neuropathology Update

We present the case of a previously healthy 41-year-old man right-handed man diagnosed with coronavirus disease 2019 (COVID-19) who developed multiple cortical ischemic infarcts. Our patient developed mild neurologic deficits despite the total volume of cerebral ischemic lesions, presumably due to involvement of non-eloquent cortex, the integrity of the collateral circulation due to his youth and good health, and mild COVID-19 disease without any significant pulmonary involvement. We discuss the coagulopathy and direct vascular effects, if any, of COVID-19 disease and compare it to other agents such as the filovirus, ad Ebola. We also outline the recent intriguing findings of vasodilation of the pulmonary vessels and the potential shunting of micro-emboli into the brain, which may explain the formation of embolic ischemic infarcts in even mild disease. Lastly, we discuss the neuropathology of COVID-19 in patients that who have succumbed to the disease and note the striking lack of direct involvement of the cerebral blood vessels.

Intermittent Vertical Diplopia as a Rare Manifestation of a Rare Cerebral Infarct: Artery of Percheron Ischemic Infarct and Sidelights on the Phenotypic Variability of Thalamic Ocular Disorders

The thalamus is a complex structure with over 40 named nuclei. Ischemic lesions of the thalamus exhibit a panorama of phenomena ranging from facial numbness to ocular and visual field disturbances to hemiplegia, behavioral disorders, and stupor. It is a dense neuronal hub with a bewildering variety of connections and functions. We present an intriguing case of intermittent vertical diplopia due to an artery of Percheron ischemic infarct of the bilateral paramedian thalami. We seize upon this opportunity to simplify the thalamic nuclei sub-divisions and their vascular supply. In this process, we outline the phenotypic variability of thalamic diplopia and ophthalmoplegia and their various underlying mechanisms.

Severe Post-Herpetic Lumbar Plexopathy Responds to Pulse Intravenous Methylprednisolone: A Case Report With a Side Note on its Parallel Semiology to Diabetic Radiculoplexopathy and the Vascular Invasiveness of the Varicella-Zoster Virus

Post-herpetic lumbar plexopathy (post-herpetic segmental paresis), immune-mediated lumbar plexopathy and diabetic radiculoplexopathy (diabetic amyotrophy) have similar and seemingly parallel semiologies. The latter two conditions have an underlying microvasculitic pathological substrate that has shown potential (yet unproven) amelioration with immunodulatory therapy. These observations gave us the motivation to treat our patient with intravenous methylprednisolone for a profound proximal left leg weakness due to post-herpetic segmental paresis. In this case report, we outline in detail the clinical and electophysiolgical phenotype of this disease and we demonstrate the spectacular improvement of left leg power that had previously remained static for three months. In the discussion section, we review the vascular invasiveness of the varicella-zoster virus.

The Clinical, Philosophical, Evolutionary and Mathematical Machinery of Consciousness: An Analytic Dissection of the Field Theories and a Consilience of Ideas

The Cartesian model of mind-body dualism concurs with religious traditions. However, science has supplanted this idea with an energy-matter theory of consciousness, where matter is equivalent to the body and energy replaces the mind or soul. This equivalency is analogous to the concept of the interchange of mass and energy as expressed by Einstein's famous equation [Formula: see text]. Immanuel Kant, in his Critique of Pure Reason, provided the intellectual and theoretical framework for a theory of mind or consciousness.  Any theory of consciousness must include the fact that a conscious entity, as far as is known, is a wet biological medium (the brain), of stupendously high entropy. This organ or entity generates a field that must account for the "binding problem", which we will define. This proposed field, the conscious electro-magnetic information (CEMI) field, also has physical properties, which we will outline.  We will also demonstrate the seamless transition of the Kantian philosophy of the a priori conception of space and time, the organs of perception and conception, into the CEMI field of consciousness. We will explore the concept of the CEMI field and its neurophysiological correlates, and in particular, synchronous and coherent gamma oscillations of various neuronal ensembles, as in William J Freeman's experiments in the early 1970s with olfactory perception in rabbits. The expansion of the temporo-parietal-occipital (TPO) cortex in hominid evolution epitomizes metaphorical and abstract thinking. This area of the cortex, with synchronous thalamo-cortical oscillations has the best fit for a minimal neural correlate of consciousness. Our field theory shifts consciousness from an abstract idea to a tangible energy with defined properties and a mathematical framework. Even further, it is not a coincidence that the cerebral cortex is very thin with respect to the diameter of the brain. This is in keeping with its fantastically high entropy, as we see in the event horizon of a black hole and the conformal field theory/anti-de Sitter (CFT/ADS) holographic model of the universe. We adumbrate the uniqueness of consciousness of an advanced biological system such as the human brain and draw insight from Avicenna's gendanken, floating man thought experiment. The multi-system high volume afferentation of a biological wet system honed after millions of years of evolution, its high entropy, and the CEMI field variation inducing currents in motor output pathways are proposed to spark the seeds of consciousness. We will also review Karl Friston's free energy principle, the concept of belief-update in a Bayesian inference framework, the minimization of the divergence of prior and posterior probability distributions, and the entropy of the brain. We will streamline these highly technical papers, which view consciousness as a minimization principle akin to Hilbert's action in deriving Einstein's field equation or Feynman's sum of histories in quantum mechanics. Consciousness here is interpreted as flow of probability densities on a Riemmanian manifold, where the gradient of ascent on this manifold across contour lines determines the magnitude of perception or the degree of update of the belief-system in a Bayesian inference model. Finally, the science of consciousness has transcended metaphysics and its study is now rooted in the latest advances of neurophysiology, neuro-radiology under the aegis of mathematics.

Decomplexifying Serum and Cerebrospinal Fluid (CSF) Serologic Testing of Neurosyphilis: A Case Report of Ocular Syphilis and Highlights of the Principles of Serologic Testing

Serologic tests for syphilis can be quite complex. The screening and confirmatory tests, which number at least eight, are mathematically interpreted as a total of 16 possible combinations, if we choose one test from each of two sets of four. However, this bewildering complexity is simplified if we apply certain principles. We reiterate and propose four axioms. First, we distinguish between treponemal versus non-treponemal tests. The former, the treponemal test, is specific for the spirochete, treponema pallidum, and is used as a confirmatory test. It rarely declines over time. The latter, the non-treponemal test, is a screening test and reflects treponemal or tissue damage, is reported as a titer, and is used to monitor disease activity. We usually need both for screening and confirmatory diagnostic testing. Secondly, for rapid plasma reagin (RPR) tests, a non-treponemal serology test titer of at least 1:8 is suggestive of syphilis, but not necessarily neurosyphilis. A false-negative test usually registers below this dilution level and may be due to the "prozone phenomenon". Serum RPR titers are usually greater than 1:32. Thirdly, a negative treponemal test in the cerebrospinal fluid excludes neurosyphilis and a positive test is highly sensitive but lacks specificity, usually due to blood contamination. Most patients with neurosyphilis will have a positive non-treponemal test in the cerebrospinal fluid (CSF) with elevated protein and pleocytosis. Fourthly, a serological cure is defined as at least a four-fold decline in a non-treponemal test titer at three and six months, or a persistently low titer after treatment. Patients who do not fulfill these criteria are known as "serofast". We describe the case of a 38-year-old man with human immunodeficiency virus-type 1 who developed bilateral optic disc edema with photopsias and transient visual obscurations.

Apperceptive Prosopagnosia Secondary to an Ischemic Infarct of the Lingual Gyrus: A Case Report and an Update on the Neuroanatomy, Neurophysiology, and Phenomenology of Prosopagnosia

Phenomenology is the philosophical study of experience and its core feature of sentience, the very ability to be conscious of a sensation and how we perceive it. Nowhere is this idea more vivid, as in the phenomenon of vision and the ability to form and sense a visual percept. The clinical entity of prosopagnosia, the ability to sense but not recognize a face, strikes at the heart of this phenomenon. We describe a classic case of selective apperceptive prosopagnosia due to an ischemic infarct of the left occipital lobe with extension to the lingual gyrus. It is well-established that acquired prosopagnosia usually involves the right more than the left occipital cortex, with localization of lesions bilaterally more than unilaterally. The ischemic infarcts strategically involve the fusiform gyrus, inferior occipital gyrus, the fundus of the posterior temporal sulcus, parahippocampal gyrus, and, rarely, lingual gyrus, which is almost always not a solitary finding. We seize upon this opportunity to explore the concept of visual prosopagnosia and outline the latest ideas on the neuroanatomical localization, neurophysiology, and classification of this intriguing phenomenon.

The Biophysics of Visual Edge Detection: A Review of Basic Principles

The mathematization of nature is an age-old concept. The Greeks sought harmony in the celestial spheres. The Arab geometers constructed a spherical geometry of the heavens. Later, Galileo Galilei arithmetized kinematics. As the centuries advanced, polymaths like the Dutchman Christiaan Huygens applied more advanced mathematics in order to understand natural phenomena. It was not until the turn of the twentieth century that a more comprehensive mathematical approach to understanding biological phenomena was sought by D’Arcy Wentworth Thompson.

This leads us to our current review of the biophysics of visual edge detection. This is an unfolding saga of stunning experimental revelations in unison with an underlying mathematical edifice. The concept of visual contrast is a fundamental idea in order to understand the phenomenon of visual edge detection. We begin with contrast visual testing and the development of frequency tuning curves, which provided an insight into the multi-channel processing of selective spatial frequencies by the visual cortex. The single-cell recordings from the simple cells of the cat visual cortex unfolded the gamma distribution curves of different neuronal firing frequencies for different spatial frequencies. The theoretical construction of the convolution of Gabor wavelets with stimulus intensity goes hand-in-hand with the experimental observation of the separation of simple visual cortical cells into even and odd functions, a spectacular finding.

In this review, we march the reader through the mathematical basics and the pathophysiologic correlates. Beginning with a simple Fourier analysis of a square wave, Weber’s biophysical law, and the gamma distribution of contrast tuning curves, we gradually introduce Fourier transforms, the uncertainty principle of waveform analysis, the basics of wavelet theory, Gabor elementary signals and transforms, the concepts of coherence, and Weyl group representation theory. Group theory provides the symmetry operations necessary to preserve the fidelity of an image as it travels from the retina and cascades up the visual cortex. Unitary operators that allow a retinal displacement of an image to be reflected by a similar displacement in the visual cortex is also a fundamental principle. Along the way, we encounter the Convolution Theorem of Fourier transforms, which is critical in constructing a visual percept. We intermittently interject relevant clinical data as we unpack the mathematical complexities.

The advanced mathematics deployed in the biophysics of vision makes for difficult reading. There is a paucity of step-by-step reviews of this subject. Our approach is heuristic and at the end of this review, one should be able to follow superficially the algorithmic steps in understanding visual edge detection using Gabor filters. Therefore, we will adopt the Socratic method of asking questions and providing answers to help us through the complex web of mathematics.

In a nutshell, we will show that a Gabor filter is the inner product of a Gaussian distribution and the wave function. The Fourier transform of the convolution of the Gabor filter and the stimulus intensity function is what is recorded from simple visual cortical cells. This is not a coincidental observation, as nature economizes and utilizes a function that minimizes the uncertainty principle of signal extraction.

Glutamic Acid Decarboxylase (GAD-65) Autoimmunity Associated With Profound Daytime Hypersomnia, Nighttime Insomnia, Mild Autonomic Neuropathy and Axonal Sensori-Motor Polyneuropathy: A Case Report on a New Phenotype

We describe the case of a 74-year-old fit and healthy man who developed a profound sleep disorder characterized by mid-day hypersomnia and debilitating insomnia. A wide range of therapies, including a large number of stimulants and hypnotics with multiple different mechanisms of action, failed to improve his condition. Trials with oral prosthetic devices and a wide range of face masks with positive pressure assistance and multiple continuous positive airway pressure (CPAP) titration studies failed to help. Along with his sleep disorder, our patient developed a slowly evolving axonal sensorimotor polyneuropathy with a subtle autonomic neuropathy. Due to the latter two conditions, a comprehensive paraneoplastic panel was obtained and revealed extremely high titer glutamic acid decarboxylase (GAD-65) autoantibodies. This was confirmed by three independent laboratories and by cerebrospinal fluid staining of rat hippocampus, revealing the classic tram-track lines along the dentate gyrus. Our patient was treated empirically with intravenous immunoglobulin. We believe that our case reveals a unique syndrome related to GAD-65 autoantibodies and adds to the growing list of GAD-65 associated diseases. This case is particularly provocative as it raises the idea to check for GAD-65 autoimmunity in patients who suffer from a profound sleep disorder resistant to conventional treatment.

Postural Orthostatic Tachycardia Syndrome Misdiagnosed as Anxiety: A Case Report with a Review of Therapy and Pathophysiology

Dizziness can be protean with multiple phenotypes. One common phenotype in the young population is postural orthostatic tachycardia syndrome (POTS). POTS has a unique cardiovascular signature with a fascinating range of etiologies and pharmacodynamic substrates. This condition can pass undiagnosed for many years and is often mistaken as an anxiety disorder due to some of its hyperadrenergic manifestations. We present one such case and then flesh out the treatment strategies, both conservative and pharmacologic. We finally describe the various underlying pathophysiologic mechanisms of POTS and its sub-types and outline the various aberrant cardiovascular reflexes. We also describe the power spectra of the heart rate variability frequency bands and their underlying physiologic basis.

Post-Herpetic Brachial Plexopathy: A Rare Case Report With a Side Note on Localizing Brachial Plexopathies and a Literature Review of Post-Herpetic Segmental Paresis

We present the case of a 77-year-old man who developed shingles over the cervical C8 dermatome followed by post-herpetic medial cord brachial plexopathy, with hand weakness and difficulty performing the pinch " O " sign. This is the very first case, to our knowledge, of a detailed presentation of a medial cord plexopathy following shingles. We review the literature of post-herpetic brachial plexopathies and discuss the magnetic resonance imaging (MRI) findings of the brachial plexus in this group of patients. We also speculate on the intriguing finding that despite frequent abnormalities on MRI such as T2 signal hyperintensity and nerve hypertrophy, contrast enhancement of nerves is exceedingly rare. Furthermore, we adumbrate on the localization of brachial plexus lesions by proposing a user-friendly diagram and table, which simplifies the diagnostic algorithm.

Cerebral Microbleeds - To Treat or Not to Treat, That Is the Question: A Case Report With a Note on Its Radiologic Deconstruction and Therapeutic Nuances

With the ubiquity of susceptibility weighted imaging (SWI), cerebral microbleeds (CMBs) are fast becoming a prevalent phenomenon. They are tightly associated with age, neurodegeneration and diverse vascular etiologies. CMBs have a unique radiological signature. Their morphology, number and topology are quite informative. They also pose a therapeutic conundrum, as they are associated with the risk of cerebral hemorrhage. We present the case of an 86-year-old woman who has a vascular dementia, Binswanger's syndrome, and coronary artery disease, who presented with more than five CMBs. We present this case in order to highlight the dilemma of anti-platelet therapy in this group of patients and we demonstrate the cardinal radiologic features of CMBs. We then segue into the pathologic correlates of CMBs and associated risk factors. We finally analyze the risk of anti-platelet therapy in the presence of CMBs, and we unfold the latest data on CMB number and anti-platelet therapy.

An Analytic Dissection of a Case of Cerebral Diplopia: Is the Human Brain a Holographic Device?

We describe the case of a 70-year-old woman who developed a cerebral infarct of the striate cortex, V1, and associated visual association cortex, V2. She presented with the visual perception disorder of a duplicated image of objects, lower fidelity, and a diaphanous copy of the original (polyopia) that was eerily similar to a hologram. We seize upon this opportunity to explain the generation of these false images. This led us to no less than the spectacular holonomic brain theory, which explains the stupendously high entropy of the brain, the storage of data in the cerebral cortex, the equipotentiality of brain tissue, and the ability of the brain to compute algorithms and perceive sensation in unison. This remarkable ability of the human brain entails the deployment of mathematical Fourier transforms and the electrical slow potentials in the highly interconnected and dense dendritic trees of the cerebral cortex. The ideas explored here are sublime and deep. These machinations are thought to be deeply ingrained in the very fabric of nature; in no less than black holes and the cosmos itself. Our case provides evidence for the holographic model of brain function in a graphic and vivid manner.

Primary Cough Headache Disorder Responds to Low Volume Therapeutic Lumbar Puncture: A Case Report With a Side Note on Therapeutics and Cranio-Spinal Dissociation

Primary cough headache disorder (PCHD) is a unique disorder with an underlying dynamic cause. Having ruled out an underlying specific etiology, it is ipso facto a diagnosis of exclusion. It has been empirically treated with cerebrospinal fluid (CSF) pressure-lowering modalities; such as indomethacin, acetazolamide and high volume CSF drainage by lumbar puncture. We describe the case of a 66-year-old man with at least a 20-year history of PCHD, who dramatically responded to low volume CSF drainage, totaling three lumbar punctures over the course of twenty years, with rapid and effective relief of headache. We review the therapy of PCHD and discuss the CSF dynamics as it pertains to lumbar and cisterna magna CSF pressures. We also propose potential mechanisms for the effectiveness of CSF lowering measures.

Isolated Musculocutaneous Neuropathy Secondary to an Immune-Mediated Brachial Plexopathy: A Case Report of a Rare Phenotype With a Side Note on Patterns of Weakness and an Update on Nerve Pathology

We describe a 50-year-old man who developed a low-frequency pattern of weakness, musculocutaneous neuropathy, with weakness of the biceps, coracobrachialis and brachialis in an immune-mediated brachial plexopathy. The aim of this article is to highlight both the low- and high-frequency patterns of weakness of the immune-mediated brachial plexopathies, and we focus on the patterns of recognition. We then segue into the pathology of the immune-mediated plexopathies and highlight the recent spectacular magnetic resonance imaging studies that demonstrate hourglass constrictions of peripheral nerves outside of the brachial plexus in afflicted patients. This opens up a window for the exciting possibility of neurolysis of constricted nerves in patients who have not responded adequately to immunotherapy.

Hemicrania Continua and Pituitary Microadenoma - Post Hoc Ergo Propter Hoc?: A Case Report With a Side Note on Intra-Sellar Pressure and the Trigemino-Autonomic Reflex

We describe the case of a 38-year-old woman whose headache phenotype transformed from episodic migraine to hemicrania continua (HC) responsive to indomethacin, as expected per diagnostic criteria. Our patient also had a non-functioning pituitary micro-adenoma which is over-represented in the trigeminal autonomic cephalgias (TAC) such as HC, pituitary adenoma being the most common intra-cranial pathology. We explore our case further by outlining in detail the neural supply of the dura of the pituitary fossa, outline the dynamics of intra-sellar pressure (ISP), and posit potential mechanisms of generation of HC in patients with pituitary micro-adenoma. We stress and further explore the remarkable observation that indomethacin, which lowers intracranial pressure, exquisitely resolves the pain of HC. Furthermore, we hypothesize that despite normal ISP, the slight elevation of ISP and mass effect impairs portal venous circulation, which may lead to venous hypertension and/or parasympathetic hyperactivity, which explains the pain and autonomic features of HC.

Cheiralgia Paresthetica or Superficial Radial Sensory Mononeuropathy: A Simple Diagnosis, A Simple Solution, and a Side Note on the Pathophysiology of the Tinel Sign

We describe the case of a sculptor who developed superficial radial neuropathy (SRN) due to blunt trauma from striking a chisel for 30 years. The lesion was localized by the anatomical topography of the superficial radial nerve, a " hot " Tinel sign, and the graphic demonstration of reduced superficial radial sensory amplitude on a nerve conduction study (NCS). Our patient also responded to a strategically placed peripheral nerve block. We go further in this article and adumbrate on the underlying pathophysiology of the very Tinel sign we are so accustomed to, a clinical sign that is frequently deployed to diagnose a variety of peripheral nerve entrapments.

Isolated Palsy of the Cisternal Segment of the Hypoglossal Nerve Due to Arterial Dissection of the V4 Segment of the Vertebral Artery: A Case Report With a Side Note on Nerve Trunk Ischemia

We describe the case of a 57-year-old woman who developed severe left-sided neck pain followed by difficulty chewing, oropharyngeal dysphagia, and dysarthria. Clinically, she developed an isolated left-sided deviation of the tongue with protrusion; an isolated cisternal hypoglossal nerve palsy. A magnetic resonance angiogram imaging study revealed a left V4 cisternal vertebral artery dissection with normal diffusion-weighted imaging of the lower medulla. We outline the anatomy, histology, and pathophysiology of ischemic injury of nerve trunks and briefly review the recent trials of vertebral and carotid artery dissections.

Chronic Progressive Spastic Paraparesis: Think of Peroxisomal Disorders - A Case Report of X-Linked Adult Onset Adrenoleukodystrophy With an Update on The Latest Treatment Strategies

The etiology of chronic progressive myelopathy can be a challenging diagnostic dilemma, especially in the absence of a structural lesion of the neural axis or a conspicuous inflammatory process. The differential diagnosis can be pleomorphic. However, the emergence of signs of adrenal dysfunction, lack of a structural lesion of the spinal cord and the emergence of cerebral demyelination should raise the suspicion of X-linked adrenoleukodystrophy (ALD). The biochemical signature of elevated serum very long chain fatty acids and a pathogenic mutation of the ATP-binding cassette subfamily D1 (ABCD1) gene is pathognomic. We present an adult variant case that marched through the classic catena of clinical syndromes: subtle adrenal dysfunction, chronic progressive myelopathy and ultimately cerebral demyelination. We outline the biochemistry, clinical semiology, pathology and therapeutic challenges in this group of patients. The unfolding disease in children and young adults can be arrested with allogenic and more recently autologous hematopoetic bone marrow transplantation. The challenge of therapy in adult patients with chronic progressive myelopathy who develop cerebral demyelination remains a therapeutic dilemma. Our case highlights the nuances of managing this group of patients and alerts the clinician to early diagnosis prior to the emergence of cerebral demyelination.

The Zeitraffer Phenomenon: A Strategic Ischemic Infarct of the Banks of the Parieto-Occipital Sulcus - A Unique Case Report and a Side Note on the Neuroanatomy of Visual Perception

We describe the remarkable case of a medically healthy right-handed 15-year-old boy who developed an ischemic infarct of the banks of the right parieto-occipital sulcus (POs). The etiology of this infarct was undetermined, that is, cryptogenic. However, the focus of this article is functional neuroanatomy, as our patient developed a specific entity; an optic flow motion deficit characterized by slow self-motion of the left half of his body (egomotion) and slow motion of the surroundings (allocentric motion) together constituting the Zeitraffer phenomenon. We describe the neuroanatomy and neurophysiology of the dorsal visual stream and correlate the localization of this type of infarct in our patient with the known functional neuroanatomy. Although lesional studies in Macaque monkeys and functional MRI studies in humans have documented the clinical-functional correlations of POs lesions and perceived motion deficits, our case is one of the very first human cases in the literature that pinpoints the Zeitraffer phenomenon to a specific and strategic circumscribed ischemic stroke in the region of the POs.

Nitrous Oxide Induced Posterior Cord Myelopathy: Beware of the Methyl Folate Trap

Posterior cord myelopathy and subacute combined degeneration of the spinal cord are well-known complications of nitrous oxide abuse. Supplementation with vitamin B12 is an effective treatment strategy to correct low serum B12 levels or normal serum levels of dysfunctional vitamin B12 associated with this pathology. In this case, we report a patient with a one-year history of heavy nitrous oxide consumption; anywhere from eight to 30 canisters of 8 grams of nitrous oxide daily. The patient’s symptoms worsened after the institution of megadoses of vitamin B12, despite normal serum folate levels. This can be explained by the phenomenon of the methyl folate trap and warrants prompt supplementation with synthetic folate. We discuss the biochemistry of nitrous oxide toxicity and the underlying mechanisms contributing to the methyl folate trap.

Bilateral Orbital Metastases Masquerading as Ocular Myasthenia Gravis: A Case Report and Review of the Literature

Ocular myasthenia gravis and orbital metastases have overlapping symptoms but divergent diagnostic and treatment strategies. Here, we present a 58-year-old female, with a 20-year history of advanced metastatic breast cancer, who presented to the neurology clinic with fatigue, muscle weakness, bilateral ptosis, and diplopia that worsened throughout the day. While the initial presentation was consistent with ocular myasthenia gravis, a subsequent evaluation revealed bilateral metastatic lesions of breast origin within the orbits. This case highlights the variable nature of metastatic disease and underscores the importance of a comprehensive neoplastic workup in patients with new-onset symptomatology and a prior history of advanced cancer despite purported remission status.

Ischemic Infarct of the Hand Knob Gyrus: Natural History, Morphology, and Localizing Value of the Omega Sulcus - A Case Report With a Side Note on the Dynamic Forces Underlying Sulci Formation

We describe a case of right-hand weakness localizable to an ischemic infarct of the hand knob gyrus of the left primary motor cortex. The hand knob gyrus is usually delimited by an omega-shaped sulcus, which is useful in outlining the posterior border of the frontal lobe. Being a cortical infarct, a potential embolic etiology was investigated and found, in keeping with previous case series reports. This finding, along with the relatively benign nature of this type of ischemic infarction, is emphasized. Identifying the omega sulcus is important as it is a reliable landmark demarcating eloquent motor cortex, which is critically important in planning surgical removal of brain tumors. In this case report, we review the largest case series of ischemic infarcts of the hand knob gyrus. We also describe the morphology of the omega sulcus, discuss the various theories underlying the convolutions or folding of the gyri of mammalian and human brains, and speculate as to why ischemic infarcts of the hand knob gyrus carry a relatively benign outcome.

Predominant Neck Extensor Muscle Weakness: A Rare Manifestation of Idiopathic Polymyositis

Dropped head syndrome (DHS) is a rare disease. It can be an isolated phenomenon or secondary to an underlying inflammatory, genetic, or sporadic neuromuscular disease. Idiopathic polymyositis as an underlying cause of DHS is rare and this association has been described very few times in the literature. We describe a case of biopsy-proven polymyositis presenting with predominant neck extensor muscle weakness. This case report goes further into analyzing the biomechanics of neck extension and putative reasons for predilection of the neck extensor muscles with advancing age in patients with DHS who have underlying idiopathic polymyositis.

Autoantibody-Negative Immune-Mediated Necrotizing Myopathy Responds to Early and Aggressive Treatment: A Case Report

Immune-mediated necrotizing myopathy (IMNM) is a rare idiopathic disease that is further classified by the presence of serum antibodies. A modicum of patients lack serum autoantibodies. Significantly elevated creatine kinase (CK) is highly characteristic of IMNM. The pathophysiology of IMNM is partially understood, and effective treatment options are limited, particularly in patients without serum autoantibodies. In this case, we report a 76-year-old male presenting with a four-month history of proximal muscle weakness. Muscle biopsy and serology confirmed the diagnosis of autoantibody-negative IMNM. Early and aggressive treatment with high-dose steroids and a course of intravenous immunoglobulin significantly reduced the patient’s symptoms and CK within three months. This case serves as an example of an effective treatment outcome in a patient with this rare idiopathic necrotizing myopathy.

Association Between Treatment-Resistant Sarcoid Myopathy and Inclusion Body Myositis

The association between sarcoid myopathy and inclusion body myositis is a rare phenomenon that is not well understood. In this case, we present a 46-year-old female with a five-year history of sarcoidosis who became refractory to treatment, experiencing progressive deterioration and muscle wasting. The patient’s distribution of muscle weakness did not follow characteristic patterns of inclusion body myositis. Yet, a subsequent deltoid biopsy revealed diagnostic findings typical of inclusion body myositis. This case report reveals an association between treatment-resistant sarcoid myopathy and the evolution of inclusion body myositis in the absence of characteristic clinical findings.