Joel A. Vilensky

Histologic analysis of neural elements in the human sacroiliac joint

Study Design. The posterior ligament of the human sacroiliac joint was examined for nerves and nerve endings using histologic and immunohistochemical techniques. Objective. To identify nerve fibers and mechanoreceptors in the posterior ligament. Summary of Background Data. According to the findings of previous studies, the human sacroiliac joint receives myelinated and unmyelinated axons that presumably conduct pain and proprioceptive impulses derived from mechanoreceptors and free nerve endings in the human sacroiliac joint. Methods. Tissue obtained from six patients was stained with gold chloride and that obtained from six additional patients was stained using antibodies specific for substance P and protein gene product 9.5. Results. The staining of joint tissue using the gold chloride technique showed myelinated and unmyelinated nerve fibers, two morphotypes of paciniform encapsulated mechanoreceptors, and a single nonpaciniform mechanoreceptor. Analysis using immunohistochemical staining for protein gene product 9.5 did not unequivocally show axons, nerve fascicles, or mechanoreceptors. Similarly, analysis based on immunohistochemical staining for substance P, one of several neurotransmitters known to signal pain from the periphery, showed reactive elements that may have been nerves, but because of background staining, could not be positively identified as such. Conclusions. The presence of nerve fibers and mechanoreceptors in the sacroiliac ligament demonstrates that the central nervous system receives information, certainly proprioceptive, and possibly pain from the sacroiliac joint. Although it is not known how the central nervous system uses such information, it seems reasonable to speculate that the proprioceptive information is used to optimize upper body balance at this joint. In addition, because the staining techniques used generally to show nerves and nerve elements in periarticular connective tissue are nonspecific, the distinction between neural and nonneural should be made on the basis of both morphologic and staining characteristics.

Locomotor behavior and control in human and non-human primates: Comparisons with cats and dogs

For many years the cat has been the accepted mammalian model for investigations on the neural control of locomotion. The results from such studies, and also similar studies on dogs, have been assumed to represent the typical mammalian condition. The primary purpose of this review is to evaluate this assumption relative to human and non-human primates. A second purpose is to acquaint investigators of mammalian locomotor behavior and control with the large amount of data available on this topic for non-human primates. The analysis shows that non-human primates are different from carnivores in footfall patterns, gaits, gait transitions, relative stride length, limb angular excursions, weight support, mechanisms of propulsion, spinal vs. supraspinal control of stepping, and possible EMG patterns. Humans exhibit more similarities with other primates than with cats or dogs, but also appear to be unique in many ways. Thus, it is clear that extrapolations of results based on cat or dog experiments may not be applicable to non-human or human primates. Furthermore, although non-human primates unquestionably make a better experimental model than cats or dogs for understanding human locomotor control mechanisms, exactly how much better remains to be determined.

The relationship between encephalitis lethargica and influenza: A critical analysis

Since encephalitis lethargica’s (EL) prevalence in the 1920s, epidemiologic and clinical debate has persisted over whether EL was caused by, potentiated by, or merely coincident with the Spanish influenza pandemic. Epidemiologic analyses generally suggest that the disorders were coincidental. Beginning in the 1970s, modern experiments on archival brain samples mainly failed to confirm a direct relationship between influenza and EL. These experimental studies have technical limitations, e.g., the appropriateness of antibodies, polymerase chain reaction (PCR) primers and controls, and the extreme paucity and age of available material. These factors render the case against influenza less decisive than currently perceived. Nevertheless, there is little direct evidence supporting influenza in the etiology of EL. Almost 100 years after the EL epidemic, its etiology remains enigmatic, raising the possibility of a recurrence of EL in a future influenza pandemic.

Serial kinematic analysis of the canine hindlimb joints after deafferentation and anterior cruciate ligament transection

OBJECTIVE AND DESIGN Transection of the anterior cruciate ligament 2 weeks after ipsilateral hindlimb deafferentation leads to osteoarthritis of the knee joint within 3 weeks. We analyzed the gait of six dogs that underwent this procedure in order to identify kinematic changes that could account for this rapid joint degeneration. All animals were video taped, 1, 3, 6, 9 and 13 weeks after surgery while they trotted on a treadmill. RESULTS In each dog, extension of the hip, knee and ankle joints of the unstable limb was increased, and the yield phase of the unstable knee was delayed or attenuated. When killed, five of six dogs showed a large full-thickness cartilage ulcer on the distal and/or anterior surface of the medial femoral condyle of the unstable knee; in the sixth dog, a smaller ulcer was observed. However, the severity of pathology in each individual was not obviously related to difference among the dogs in postoperative joint kinematics. CONCLUSIONS These data, and results of prior studies in humans and dogs, suggest that knee hyperextension resulting from limb deafferentation, and knee instability resulting from anterior cruciate ligament transection, operate in concert to create a mechanical environment (i.e., increased tibiofemoral separation and changes in the loading of articular surfaces) that results in rapid joint breakdown.

Trot-gallop gait transitions in quadrupeds

Although the kinematics, mechanics, energetics and mathematics of trot-gallop gait transitions have been discussed in previous papers, no one article has tried to assimilate all the information. This review paper does this and includes a summary of the relatively new engineering (mathematical) approach to analyzing these transitions developed by Schoner et al. (29). The paper also presents unpublished data on gait transitions in cats and monkeys, and attempts to develop some general principles pertaining to trot-gallop transitions. Finally, the paper highlights areas where additional information is needed.

Horsley was the first to use electrical stimulation of the human cerebral cortex intraoperatively

Fedor Krause has previously been credited with being the first surgeon to use electrical stimulation to define epileptic foci in the human cerebral cortex before extirpation. We provide evidence indicating that Krause was probably preceded by Horsley, and Bidwell and Sherrington in England, and by Keen in the United States. Sir Victor Horsley apparently first used electrical stimulation diagnostically in 1884 and slightly later (1886) to define epileptic foci.

Vacuum phenomenon: Clinical relevance

Vacuum phenomenon (VP) is an anatomical entity of potential confusion in the diagnosis and evaluation of joint pathology. Observation of this phenomenon has been demonstrated on basic radiographs, computed tomography, and magnetic resonance imaging. Although VP is most often associated with degenerative joint disease, it is observed with other pathologies. Two problematic scenarios can occur: a false‐positive diagnosis of serious pathology instead of benign VP and a false‐negative diagnosis of benign VP with a more serious underlying process Despite this potential for confusion, criteria for distinguishing VP from other causes of joint pain and for evaluating a suspected case of VP have not been fully established. We reviewed the literature to determine underlying mechanism, symptomology, associated pathologies, and clinical importance of VP. The formation of VP can be explained by gas solubility, pressure–volume relationships, and human physiology. CT, GRE‐MRI, and multipositional views are the best imaging studies to view VP. Although most cases of VP are benign, it can be associated with clinical signs and symptoms. VP outside the spine is an underreported finding on imaging studies. VP should be on the differential diagnosis for joint pain, especially in the elderly. We have proposed criteria for diagnosing VP and generated a basic algorithm for its workup. Underreporting of this phenomenon shows a lack of awareness of VP on the part of physicians. By identifying true anatomic VP, we can prevent harm from suboptimal treatment of patients. Clin. Anat. 27:455–462, 2014.

The neglected cranial nerve: Nervus terminalis (cranial nerve N)

The nervus terminalis (NT; terminal nerve) was clearly identified as an additional cranial nerve in humans more than a century ago yet remains mostly undescribed in modern anatomy textbooks. The nerve is referred to as the nervus terminalis because in species initially examined its fibers were seen entering the brain in the region of the lamina terminalis. It has also been referred to as cranial nerve 0, but because there is no Roman symbol for zero, an N for the Latin word nulla is a better numerical designation. This nerve is very distinct in human fetuses and infants but also has been repeatedly identified in adult human brains. The NT fibers are unmyelinated and emanate from ganglia. The fibers pass through the cribriform plate medial to those of the olfactory nerve fila. The fibers end in the nasal mucosa and probably arise from autonomic/neuromodulatory as well as sensory neurons. The NT has been demonstrated to release luteinizing‐releasing luteinizing hormone and is therefore thought to play a role in reproductive behavior. Based on the available evidence, the NT appears to be functional in adult humans and should be taught in medical schools and incorporated into anatomy/neuroanatomy textbooks. Clin. Anat. 27:46–53, 2014.

Movement disorders associated with encephalitis lethargica : A video compilation

Encephalitis lethargica (EL; epidemic encephalitis; von Economos disease) often presented with a movement disorder, and the motor consequences of postencephalitic parkinsonism (PEP) were characteristic of the chronic sequelae of this condition. PEP was similar to Parkinsons disease but was more variable and had some distinct features such as oculogyric crises. Although two previous publications have included video images of the movement disorders associated with EL and PEP, the sequences presented were typically short, showed only a few patients, and did not include the work of several neurologists who had the foresight to preserve filmed images of their patients. We describe the most complete record of EL and PEP moving images that have been preserved and make them available in edited form.

A historical analysis of the relationship between encephalitis lethargica and postencephalitic parkinsonism: A complex rather than a direct relationship

Postencephalitic parkinsonism has been considered unique among disorders with parkinsonian features because it is believed to have a unitary etiology associated with the virus that presumably caused encephalitis lethargica. Careful analysis of the historical record, however, suggests that this relationship is more complex than commonly perceived. In most cases, the diagnosis of acute encephalitis lethargica was made post hoc, and virtually any catarrh‐like illness was considered to have represented encephalitis lethargica, often after an oral history‐taking that was undoubtedly subject to patient recall and physician bias. Also, postencephalitic parkinsonism and oculogyric crises were not recognized as sequelae to encephalitis lethargica until well after other sequelae such as movement disorders and mental disturbances had been identified (see previous paper). We suggest here that the relationship between encephalitis lethargica and postencephalitic parkinsonism is not simplistic, i.e., encephalitis lethargica was not solely responsible for the etiology of postencephalitic parkinsonism, thus aligning the latter with most other parkinsonian disorders that are now believed to have multiple causes.