Charles Skinner Hallpike and the beginnings of neurotology

Therapies to Restore Consciousness in Patients with Severe Brain Injuries: A Gap Analysis and Future Directions

Background/Objective

For patients with disorders of consciousness (DoC) and their families, the search for new therapies has been a source of hope and frustration. Almost all clinical trials in patients with DoC have been limited by small sample sizes, lack of placebo groups, and use of heterogeneous outcome measures. As a result, few therapies have strong evidence to support their use; amantadine is the only therapy recommended by current clinical guidelines, specifically for patients with DoC caused by severe traumatic brain injury. To foster and advance development of consciousness-promoting therapies for patients with DoC, the Curing Coma Campaign convened a Coma Science Work Group to perform a gap analysis.

Methods

We consider five classes of therapies: (1) pharmacologic; (2) electromagnetic; (3) mechanical; (4) sensory; and (5) regenerative. For each class of therapy, we summarize the state of the science, identify gaps in knowledge, and suggest future directions for therapy development.

Results

Knowledge gaps in all five therapeutic classes can be attributed to the lack of: (1) a unifying conceptual framework for evaluating therapeutic mechanisms of action; (2) large-scale randomized controlled trials; and (3) pharmacodynamic biomarkers that measure subclinical therapeutic effects in early-phase trials. To address these gaps, we propose a precision medicine approach in which clinical trials selectively enroll patients based upon their physiological receptivity to targeted therapies, and therapeutic effects are measured by complementary behavioral, neuroimaging, and electrophysiologic endpoints.

Conclusions

This personalized approach can be realized through rigorous clinical trial design and international collaboration, both of which will be essential for advancing the development of new therapies and ultimately improving the lives of patients with DoC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01227-y.

Margaret Dix, Charles Hallpike and the 'Lagerungs' Manoeuvre

The main objective of this manuscript is to describe some personal and professional aspects of two outstanding researchers and pioneers in neuro-otology. Among other achievements, Margaret Ruth Dix, and Charles Skinner Hallpike, designed the most-used provocative test for positional nystagmus for the diagnosis of lithiasis in the vestibular posterior semicircular canal.

Studies of caloric vestibular stimulation: implications for the cognitive neurosciences, the clinical neurosciences and neurophilosophy

OBJECTIVE

Caloric vestibular stimulation (CVS) has traditionally been used as a tool for neurological diagnosis. More recently, however, it has been applied to a range of phenomena within the cognitive neurosciences. Here, we provide an overview of such studies and review our work using CVS to investigate the neural mechanisms of a visual phenomenon - binocular rivalry. We outline the interhemispheric switch model of rivalry supported by this work and its extension to a metarivalry model of interocular-grouping phenomena. In addition, studies showing a slow rate of binocular rivalry in bipolar disorder are discussed, and the relationship between this finding and the interhemispheric switch model is described. We also review the effects of CVS in various clinical contexts, explain how the technique is performed and discuss methodological issues in its application.

METHODS

A review of CVS and related literature was conducted.

RESULTS

Despite CVS being employed with surprising effect in a wide variety of cognitive and clinical contexts, it has been a largely underutilized brain stimulation method for both exploratory and therapeutic purposes. This is particularly so given that it is well tolerated, safe, inexpensive and easy to administer.

CONCLUSION

CVS can be used to investigate various cognitive phenomena including perceptual rivalry, attention and mood, as well as somatosensory representation, belief, hemispheric laterality and pain. The technique can also be used to investigate clinical conditions related to these phenomena and may indeed have therapeutic utility, especially with respect to postlesional disorders, mania, depression and chronic pain states. Furthermore, we propose that based on existing reports of the phenomenological effects of CVS and the brain regions it is known to activate, the technique could be used to investigate and potentially treat a range of other clinical disorders. Finally, the effects of CVS (and its potential effects) on several phenomena of interest to philosophy suggest that it is also likely to become a useful tool in experimental neurophilosophy.

Perspective on the vestibular cortex throughout history

The human vestibular organ transmits sensory information to various components of the central nervous system related to head movement and, obviously, among these components, to its terminal region(s) in the vestibular parts of the cerebral cortex. Study of vestibular structures dates back to historical epochs when primitive considerations on cerebral global function were made without knowledge of a cerebral cortical region related to vestibular function. At the time of Menière in the 19th century, patients with vertigo were defined as having cerebral congestion. Cerebral mapping and computational anatomy in the 20th century significantly expanded our knowledge of cerebral structure and its function and the concept of cerebral processing of a variety of types of information, including that generated by the vestibular system. These modern techniques include nuclear magnetic resonance imaging, functional magnetic resonance imaging, and positron emission tomography. These techniques have allowed researchers to define the cortical representation of the vestibular system in human beings and in other species, a representation generally assumed to be located in various cerebral temporal and parietal regions. Although vestibular activation has been recorded in frontal lobe regions, the main vestibular cortical zone has been defined as being located in the parietal lobe; others have recognized a vestibular cortical function in the insula.