Physical Medicine and Rehabilitation

Though its existence has been known for well over 30 years, only recently has the supplementary motor area (SMA) and its role in the cortical organization of movement come to be examined in detail by neuroscientists. Evidence from a wide variety of investigational perspectives is reviewed in an attempt to synthesize a conceptual framework for understanding SMA function. It is suggested that the SMA has an important role to play in the intentional process whereby internal context influences the elaboration of action. It may be viewed as phylogenetically older motor cortex, derived from anterior cingulate periarchicortical limbic cortex, which, as a key part of a medial premotor system, is crucial in the “programming” and fluent execution of extended action sequences which are “projectional” in that they rely on model-based prediction. This medial system can be distinguished from a lateral premotor system postulated to have evolved over phylogeny from a different neural source. An anatomico-physiologic model of the medial premotor system is proposed which embodies the principles of cyclicity and reentrance in the process of selecting those neural components to become active in conjunction with the performance of a particular action. The postulated dynamic action of this model in the microgenesis of a discrete action is outlined. It is concluded that although there is a great deal to be learned about the SMA, a convergence of current evidence can be identified. Such evidence suggests that the SMA plays an important role in the development of the intention-to-act and the specification and elaboration of action through its mediation between medial limbic cortex and primary motor cortex.

The alien hand sign was first described by Brion and Jedynak as a "feeling of estrangement between the patient and one of his hands." The affected hand frequently shows a grasp reflex and an instinctive grasp reaction as well as elements of what Denny-Brown referred to as a "magnetic apraxia" associated with frontal lobe damage. Most notably, however, the affected hand is observed to perform apparently purposive behaviors that are perceived as being outside the volitional control of the patient. The patients interpret the behavior of their own affected limb as being controlled by an external agent. They do not feel that they are initiating or controlling the behavior of the hand and often express dismay at the hand's "extravolitional" activity. The patients attempt to control behavior of the alien hand with the unimpaired hand by forcibly restraining the affected limb, an act that may be termed "self-restriction." In this paper, we report an additional four cases of alien hand sign in right-handed subjects: two involving the right hand and two involving the left hand. In each case, the clinical findings were associated with extensive unilateral damage of the medial frontal cortex of the hemisphere contralateral to the affected hand. Furthermore, the alien movement gradually disappears over the course of 6-12 months after the stroke. These clinical case studies are presented and discussed in the context of the "dual premotor systems hypothesis," an anatomicophysiological model that proposes that action is organized by two separate but interactive premotor brain systems corresponding to evolutionarily defined medial and lateral cortical moieties. It is hypothesized that the alien mode behavior results from unconstrained activity of the lateral premotor system in the damaged hemisphere. The residual volitional control in the limb occurs through the activity of the intact medial premotor system of the ipsilateral hemisphere. Recovery may occur through extension of these ipsilateral control mechanisms by compensatory changes in subcortical systems controlling hemispheric activation associated with adaptive behavior. This observation may be important in understanding mechanisms involved in motor recovery after stroke.

This issue of Topics in Stroke Rehabilitation explores the theme of medical phenomenology and stroke rehabilitation through open peer commentary format. The theme is introduced by a brief summary and overview of phenomenology as a branch of philosophy whose focus is the development of methodology for describing and ordering human experience. The application of this philosophical approach to medicine in general and stroke rehabilitation in particular is then considered. An approach to patients informed by both phenomenology and science provides a more complete, holistic, and humanistic framework than science alone. Phenomenology helps the clinician to understand the importance of narrative, the process of adaptation at the level of the integrated whole person, and the important role of context in determining how recovery unfolds. Embodiment is presented as an organizing principle that links the nature of conscious experience in the lived body and the basic transformation in experience and function associated with an acquired pathology such as stroke. Finally, the nature of open peer commentary is considered and introduced in terms of how it has been specifically implemented in this issue of Topics in Stroke Rehabilitation.

A study of ethics requires the ability to examine and understand the nature of the experience of the subject and recognize the foundational status of dynamic process and relationality. A new postmodern philosophic framework that recognizes the fundamental importance of relational functions is required to address the complex ethical dilemmas encountered in brain injury care adequately. Brain injury is best understood as 'an assault on the personal' played out in the context of the subjectivity of the injured person. Using an approach informed by 'semioethics,' the exceptionality of the injured person is fully honored and respected. 'Semioethics' can provide a framework for navigating the consensus-seeking dialogical inquiry that strives for a response to an ethical dilemma.

Numerous efforts have been made to improve the sensitivity and specificity for the electrodiagnosis (edx) of carpal tunnel syndrome (CTS). The concept of comparison of DLs has developed over the past few decades to increase the electrodiagnostic sensitivity of CTS, especially in cases where routine DL measurements are within normal one of these efforts have addressed the elderly population or the influence advancing age could have upon the interpretation of nerve conduction studies (NCS) for the edx of CTS. People over the age of 60 years comprise the largest segment of our p~p u l a t i o n ,~ yet no standardized data for DL comparisons of the elderly population exists in the literature to provide an accurate interpretation of electrodiagnostic findings for the edx of CTS. The purpose of this study was to establish normative data for within hand distal latency (DL) comparisons in the healthy el

Ttns research project was approved by the Staff Research Committee and the lnbtitutional Review Board of the Moss Rehabilitation Hospital. Funding was approved and allocated by the Staff Research Committee. This research was presented in abstract form at the Annual Spring Meeting of the Association of Academic Physiat-rist\ held in Albuquerque. NM in March 1993. No commercial party having n direct financial interest in the results of the research supporting thic article has or will confer a benefit upon the authors or upon any organizatmn with which the authora are associated. Reprint requests to Willlam J. Hennessey, MD. The Ohio State University. Depanment of Physical Medicine and Rehabilitation. Dodd Hall. 480 West 9th Avenue. Columbus. OH 43110.

unfolds, this perspective can shed light on the practice of brain injury rehabilitation. More generally, biosemiotics can offer a scientific foundation for medical rehabilitation, involving the optimization of consequential functionality and the regaining of meaningful performance capacity. Thus, biosemiotics provides insight into brain injury rehabilitation as an existential, person-centered enterprise.

In this paper, an extension of the distinction between the Phi- and the Sigma-sciences and proposed differentiation between the 'physical' and 'semiotic' scientific approaches is brought forward based on an expansion of Table 1 in Kull (2009) and the concepts presented in this seminal paper by Kalevi Kull. This extension is based on a very wide-ranging, speculative elaboration of the so-called 'Dirac Diagram' that has been attributed to Paul Dirac (1902-1984), a distinguished quantum physicist of the 20th century, which arose out of considerations arising from quantum physics. It is maintained that this distinction between the physical sciences and the semiotic sciences is far-reaching and fundamentally transdisciplinary, and is hinted at by the divergence of the basic principles of quantum physics from those of classical physics.

The purpose of this study was to evaluate prospectively and analyze the relationship of tibial nerve H reflex latency to age, sex, leg length, and skin temperature in a large healthy elderly population. The H reflex was recorded bilaterally in 92% of 103 carefully screened individuals aged 60-88 years. The mean H reflex latency was 30.8 (SD = 2.6) and 30.7 (SD = 2.6) ms for right and left legs, respectively. A high correlation (r = 0.55, P < 0.05) was present between H reflex latency and leg length. No significant correlation existed for H reflex latency and age. The upper normal limit for the difference between right and left H reflex latencies was 1.8 ms. This limit is greater than that reported in the literature for younger individuals due to a larger standard deviation. These findings suggest that aging increases the between-leg variability of H reflex latency in individuals. This greater difference must be taken into account when using side-to-side H reflex latency comparison to detect unilateral pathology in the elderly.