Meta-analysis of erythrocyte Na,K-ATPase activity in bipolar illness

Sodium, potassium-activated adenosine triphosphatase (Na,K-ATPase) pump activity has been variously reported to be increased, decreased, or unchanged in bipolar patients. To explore this association we conducted a meta-analysis of the available literature. All papers containing data on erythrocyte Na,K-ATPase activity were reviewed independently by both authors. A meta-analysis of these data was accomplished by standard procedure. We found a significant mood-state-related decrease in Na,K-ATPase activity in both manic and bipolar depressed patients when compared to euthymic bipolar patients, but not when ill patients were compared to normal controls. The overall change can be characterized as small to moderate in magnitude.

Completed suicides and emergency psychiatric evaluations: the Louisville experience

Suicide is one of the most serious outcomes of psychiatric illness, and the most extreme intervention (involuntary hospitalization) can be exercised if this event is likely. Despite this, the rate of suicide has remained fairly consistent at 1.1-1.4%. In an ongoing effort of identifying factors that can predict subsequent suicides, we retrospectively examined the records of individuals who completed suicides in Jefferson County, January 1997 through September 1998, and who were evaluated at the Emergency Psychiatric Service (EPS) at University of Louisville Hospital. Fifteen of the 132 (11.4%) subjects who completed suicide were evaluated at some point in time at EPS. Only 8 (6.1%) were seen within 60 days of the fatal event. This represents less than 0.1% of the total 9,469 patients seen at the EPS during this time period. No specific factors could be identified that predicted imminent suicide. Given the inaccuracy in being able to predict suicide, clinicians need to continue to be vigilant when assessing acutely distressed substance abusing or psychiatric patients.

Alpha 2 isoform of the Na,K-adenosine triphosphatase is reduced in temporal cortex of bipolar individuals

BACKGROUND

The pathophysiology of bipolar illness has been associated with changes in transmembrane ion flux and redistribution of biologically active ions. The recent identification of multiple isoforms of Na,K-adenosine triphosphatase (ATPase) alpha and beta subunits raises the possibility of altered pump isoform expression.

METHODS

We determined Na,K-ATPase alpha subunit expression in postmortem temporal cortex gray matter from individuals suffering from bipolar disorder, schizoaffective disorder, schizophrenia, and matched normal controls. Quantification of isoform expression was accomplished via densitometric scanning of Western blots utilizing isoform-specific antibodies.

RESULTS

Bipolar individuals exhibited a significant reduction in the abundance of the alpha 2 isoform of Na,K-ATPase compared to normal controls. Schizophrenic and schizo-affective brains were not significantly different from normal controls.

CONCLUSION

These data suggest that previously observed abnormalities in regulation and distribution of ions in bipolar illness may be related to specific alpha 2 dysregulation.

Bipolar illness

BACKGROUND

Within the past 5 years, several factors have altered our view of the diagnosis, prognosis, treatment, and genetics of bipolar illness.

METHODS

Significant advances in these areas are reviewed.

RESULTS

Diagnostic changes include establishment of symptom duration requirements that limit confusion with affective instability. Prognostic insights include the realization that illness likely begets illness and, conversely, that adequate control is probably instrumental in improving long-term prognosis. Therapeutic advances are marked by the Food and Drug Administration approval of divalproex for acute mania.

CONCLUSIONS

Genetic and family studies suggest that (1) bipolar illness is a discrete condition, not related to unipolar depression; and (2) bipolar illness may manifest a phenomenon known as anticipation (worsening of the disease with succession generations), which may be related to a specific nucleic acid abnormality.

Triplet repeat gene sequences in neuropsychiatric diseases

The human genome has many nucleotide repeat sequences. These range from a single repeating base to entire duplicated genes. Expansion of repeating triplets of nucleotides in the genome has recently been associated with nine degenerative and developmental neuropsychiatric diseases: fragile X syndrome, fragile X-linked mental retardation, myotonic dystrophy, Friedreich's ataxia, spinal and bulbar muscular atrophy, Huntington's disease, spinocerebellar ataxia type 1, dentatorubral-pallidoluysian atrophy, and Machado-Joseph disease. These diseases are all conditions of the central nervous system; in all of them, the inheritance pattern usually exhibits the phenomenon of anticipation (defined as progressively earlier age of onset or a worsening disease severity over successive generations), and the severity of the phenotypic expression and penetrance appears to be related to the extent of the triplet expansion. Identification of this pathological genetic phenomenon solves several of the mysteries that surrounded these conditions but raises many important questions regarding pathogenic mechanisms that may be shared. There is some indication that triplet expansions may also underlie other neuropsychiatric conditions such as schizophrenia or bipolar disorder.

Lithium prevents ouabain-induced behavioral changes. Toward an animal model for manic depression

Both mania and bipolar depression have been associated with decrements in the activity of the sodium and potassium-activated adenosine triphosphatase (Na,K-ATPase) membrane pump. Although the role of this observation in the pathophysiology of bipolar illness is unclear, it has been proposed that this defect could be central to the pathogenesis of the illness. In an effort to test this hypothesis, the authors examined the efficacy of lithium pretreatment in attenuating behavioral changes secondary to acute administration of a single intracerebroventricular (i.c.v.) dose of the Na,K-ATPase-inhibiting compound, ouabain, in the Sprague-Dawley rat. Ouabain (10(-3)M) significantly decreased motor activity in automated activity monitors. Lithium pretreatment for 7 d totally prevented this effect. These preliminary data suggest that i.c.v. ouabain administration in the rat may prove to be a viable animal model for bipolar illness.

Structure of music may influence cognition

Classical music has been said to enhance cognition, which effect may be related to musical structure. 19 subjects who listened to highly structured music scored somewhat higher afterwards on cognitive performance than the 15 who listened to less structured music. Since this did not reach statistical significance, other as yet unidentified factors may also be involved.

ECG intervals in acute bipolar and schizophrenic relapse

Psychosis in general and acute relapse of bipolar illness, in particular, are associated with elevated catecholamine excretion, cardiovascular changes, and changes in intracellular calcium concentration. In an effort to determine if these changes result in observable ECG abnormalities, we retrospectively examined ECG parameters of acutely disturbed bipolar and schizophrenic patients. There were no discrete patterns of abnormalities, and no significant differences were observed between the two patient groups. Most ECG changes in acutely hospitalized bipolar and schizophrenic patients appear to be benign.

Nerve conduction velocity and H-reflex recovery in bipolar illness

Bipolar illness may be characterized by dysregulation and dysfunction of biologically active ions and ion pumps, respectively. In an effort to examine whether purported physiologic abnormalities may have functional counterparts, nerve conduction velocities (NCVs) and H-reflex recovery were examined in 7 acutely manic, 11 euthymic bipolar, 13 remitted schizophrenic, and 6 normal control individuals. All electrophysiologic tests were clinically normal. However, euthymic bipolar patients had significantly slower NCVs than either manic or normal individuals. Percent decrement of H-reflex recovery was nonsignificantly increased in manic versus euthymic bipolar subjects. Data analysis suggests lithium was not responsible for these changes. These data indicate that different mood states in bipolar illness are associated with alterations in electroneurophysiologic function.

Effects of chronic episodic hypoxia on monoamine metabolism and motor activity

Chronic episodic hypoxia produces a wide array of cardiovascular dysfunctions in rats, including increases in blood pressure, heart rate, and sympathetic nerve activity. The action of episodic hypoxia might be related to low oxygen itself (hypoxemia) and/or combined with low CO2 (hypocapnia) resulting from hyperventilation. It is unknown whether or not the cardiovascular abnormalities are related to alterations in the central nervous system (CNS) that may be manifested as neurotransmitter and/or behavioral changes. In this study, we investigated effects of episodic eucapnic and hypocapnic hypoxia on monoamine metabolism in both CNS and adrenal glands, and on motor behavioral activity. Thirty-five male rats were divided into 3 groups. Experimental rats were exposed 8 h daily to varying fractional concentrations of inspired oxygen (FiO2) and carbon dioxide (FiCO2) for 35 days. These consisted of brief exposures (3-6s) of episodic (twice every min) eucapnic (3.5% FiO2 and 10% FiCO2, n = 6) or hypocapnic (3.5% FiO2 and 0% FiCO2, n = 14) hypoxia, or room air (21% FiO2 and 0.03% FiCO2, n = 15). Norepinephrine, dopamine, serotonin, and their metabolites in the hypothalamus, hippocampus, and adrenal glands were measured by high-performance liquid chromatography (HPLC). Spontaneous behavioral activity was assessed for 30 min by automated activity monitors. Episodic hypocapnic hypoxia produced a decrease in dopamine turnover and eucapnic hypoxia increased norepinephrine levels in the hypothalamus. Animals exposed to hypocapnic hypoxia also exhibited a consistent increase in horizontal (walking) and vertical (rearing) activity, as well as in total activity time. From these results, it is concluded that episodic eucapnic and hypocapnic hypoxia may affect metabolism of different neurotransmitters in the CNS.

Clues to depression in primary care practice

Depression is a common but highly treatable mood disorder. Unfortunately, two thirds of depressed patients may never receive appropriate intervention. Because of individual and societal barriers to the diagnosis, depressive symptoms often go unrecognized. However, primary care physicians are in a unique position to surmount these obstacles by being alert to manifestations of the disorder. Treatment with antidepressant drugs, psychotherapy, electroconvulsive therapy, or a combination of these is very efficacious. The choice of method is based on such factors as history of previous response, severity of disease, concomitant medical illness, and patient preference.

An animal model for mania: preliminary results

1. In human bipolar patients mania and bipolar depression are both characterized by decreased membrane Na,K-AtPase activity. Additionally, digoxin neurotoxicity in patients frequently presents with symptoms of mania or depression. 2. These findings suggest that central nervous system Na,K-ATPase inhibition may play a pathophysiologic role in bipolar illness. 3. The authors tested this hypothesis by administering intracerebroventricular (i.c.v.) ouabain to rats at sublethal doses. The authors then measured behavioral activity as total square crossings in an open field. 4. Motoric activity was significantly increased by i.c.v. administration of 5 microliters of ouabain at 10(-3) M. This preliminary study suggests that i.c.v. ouabain administration may provide a useful animal model of mania that is based on observed biochemical changes in humans.

The Na,K-ATPase hypothesis for bipolar illness

A cellular model for bipolar illness is presented. It is propounded that alterations in the activity of the membrane sodium- and potassium-activated adenosine triphosphatase pump (Na,K-ATPase) may be responsible for alterations in neuronal excitability and activity. Specifically, a reduction in Na,K-ATPase activity can lead to both mania and depression by increasing membrane excitability and decreasing neurotransmitter release, respectively. Supporting evidence is reviewed, and clinical and research implications are discussed.

The role of parkinsonism and antiparkinsonian therapy in the subsequent development of tardive dyskinesia

Tardive dyskinesia (TD) is a side effect of prolonged neuroleptic treatment presenting as abnormal involuntary movements. This troublesome disorder occurs in only 15-30% of patients taking neuroleptics, suggesting that these individuals may be physiologically distinct so as to be predisposed. This study analyzed possible factors contributing to TD development. Fifty patients on depot neuroleptics for more than 7.1 years were prospectively examined for TD and drug-induced parkinsonism (DIP) using the Smith-Trims rating scale for an average of 5 years. The patients were assessed for the severity of the movement and if the movement increased or decreased with respect to neuroleptic dosage, anticholinergic dosage, parkinsonism, and other related factors. Both TD and DIP increased over time. In the patients whose dose of neuroleptic decreased, the increase in TD ratings was not significant. Using a forward stepwise regression DIP was found to increase as TD worsened but did not appear to predict subsequent TD development. Anticholinergic treatment showed a less significant correlation with the change in TD. These results have implications for the management of combined TD and DIP presentation.

Teaching psychopharmacology to psychology interns

A group of psychology interns were given a brief course in psychopharmacology. In follow-up questionnaires from 14 doctoral psychologists 6 months and 2.7 years after graduation respondents stated that the course increased knowledge and confidence in their collaboration with physicians.

Evaluating change: a simple technique for determining the statistical significance of proportional criteria

A simple method to calculate statistically significant differences between proportions is presented to evaluate changes in quality assessment and utilization data. The authors believe that this calculation could be a valuable analytic method for evaluating changes in monitored criteria, particularly in the assessment of criteria measuring high-volume events.

Possible role of endogenous ouabain-like compounds in the pathophysiology of bipolar illness

A large number of studies have documented a mood-state-related decrease in blood cell sodium, potassium-activated adenosine triphosphatase (Na, K-ATPase) activity in acutely ill bipolar patients. While it has been proposed that this enzymatic change may be central to the pathophysiology of bipolar illness, its genesis has remained obscure. Recent advances in the isolation and characterization of endogenously produced ouabain- or digoxin-like compounds suggest a possible mechanism by which these mood-state-related changes can come about. We herein propose that the hypothalamic-pituitary-adrenal dysregulation frequently documented in major mood disorders may underlie a pathological increase in the production of endogenous ouabain-like compounds which excessively suppresses Na, K-ATPase activity and results in pathological mood and energy alteration.

A neuropsychiatric program for HIV-infected individuals

Designing an effective, outpatient, community-based neuropsychiatric program for persons infected with human immunodeficiency virus-1 (HIV) is challenging because the affected population is diverse. The individuals must cope with a multitude of complications while anticipating a shortened life span. Behavioral and emotional complications are common and may be reactive, idiopathic, or organic. An effective program must provide neuropsychiatric evaluations and give access to ongoing supportive and psychotherapeutic services that take into account problems unique to HIV-infected individuals. Neuropsychiatric evaluations were performed on 80 infected patients. The HIV-seropositive individuals (n = 60) were compared with patients with acquired immunodeficiency syndrome (AIDS) (n = 20) using several clinical measures. Patients in the early stages of HIV infection suffered from more frequent major depressive episodes and ongoing substance abuse than patients with advanced disease. Cognitive impairment and psychosis, however, were primarily related to AIDS.

Impact of treating involuntarily admitted schizophrenics on an open unit

When involuntary psychiatric patients are treated on unlocked units, problems may arise as to resource expenditure and the ability to provide optimal psychiatric care. This study investigates the problem and possible solutions.

Interleukin-1 alpha and interleukin-2 in cerebrospinal fluid of schizophrenic subjects

1. It has been postulated that the interrelated processes of neurodegeneration, neuroplasticity, and neuroimmunological abnormalities may play a role in the pathophysiology of schizophrenia. Since, interleukins are produced in the central nervous system and have cytokine and growth promoting properties, they are an obvious choice to consider in these neural processes. 2. Cerebrospinal fluid obtained from schizophrenic patients, on and off medications, and from normal controls was assayed for interleukin-1 alpha (IL-1 alpha) and interleukin-2 (IL-2) using a sensitive enzyme-linked immunoassay. 3. IL-1 alpha concentration were below the detection limits of the assay in both controls and schizophrenics. 4. IL-2 levels were under 1 ng/ml CSF in nearly all subjects. There was no significant difference in IL-2 levels between medicated and medication-free schizophrenics or when patients were compared to controls.

Does motor cerebral dominance develop secondary to sensory dominance?

Current research and theoretical frameworks for understanding motor dominance assume that motor dominance is primary. Various developmental clues, however, suggest that the maturation of proprioceptive sensory processing predates that of motor control. We hypothesized that the observed adult pattern of lateralized motor dominance may develop as a consequence of preexisting lateralized "sensory" or "proprioceptive dominance." To test whether motor preference could develop in response to sensory dominance, we investigated sighting eye dominance, eye lid winking, and handedness in 164 individuals. Subjects winked the nondominant eye significantly more frequently than the dominant eye and independently of their handedness, lending partial support to the idea that motor function can develop in response to sensory function. Specific investigation of the development of the proprioceptive system would be needed to evaluate whether lateralization of motor handedness develops as a consequence of "proprioceptive" lateralization.

Is the Na(+)-K(+)-ATPase the link between phosphoinositide metabolism and bipolar disorder?

Recent experimental work suggests involvement of the phosphatidyl inositol second messenger system in the biochemical mechanism of lithium action, but this work has not shed light on the pathophysiology of bipolar illness. Earlier work had established reduction in sodium-potassium-activated adenosine triphosphatase (Na(+)-K(+)-ATPase) activity as a consistent marker of mood in bipolar illness but had only partially illuminated mechanisms of the action of lithium. Now, advances from research in diabetic neuropathy suggest that inositol phosphate and diacylglycerol metabolism are indeed linked to Na(+)-K(+)-ATPase activity. The data are compatible with a model in which a primary decrease in Na(+)-K(+)-ATPase activity in bipolar patients can stimulate an increase in phosphoinositide hydrolysis, thereby generating the equivalent of a second messenger signal in the absence of a first message. Lithium appears to act by blocking this false second message.

Creatine kinase and enolase: intracellular enzymes serving as markers of central nervous system damage in neuropsychiatric disorders

A frequently used method to assess cellular dysfunction and damage in humans is to document the presence of uniquely intracellular proteins in extracellular spaces. Thus, increased plasma levels of transaminases generally reflect hepatocellular damage (Lieber 1978), increases in the cardiac fractions of creatine kinase (CK, or CPK for creatine phosphokinase) or lactate dehydrogenase (LDH) are diagnostic for myocardial infarction (Armstrong et al. 1979; 1982), and increases of skeletal muscle fractions of CK may indicate myopathy (Goto 1974; Ford 1984). Similarly, a number of enzymes and proteins serve as tumor markers in a variety of malignant cancer (e.g., Concannon et al. 1974; Foti et al. 1977).

AIDS dementia-related psychosis: is there a window of vulnerability?

Human immunodeficiency virus (HIV) frequently enters the central nervous system (CNS) soon after infection, and frequently produces a wide variety of neurologic, cognitive, and psychiatric complications. Although, the entire spectrum of psychiatric illnesses may be seen in individuals with HIV infection, most are probably not directly caused by the virus. Psychiatric manifestations that are the direct result of HIV infection are usually seen in the setting of HIV-associated dementia. In this paper, it is proposed that these psychiatric manifestations of HIV infection can be phenomenologically separated into positive and negative symptoms. Negative symptoms are deficit states presenting as cognitive, social, or motivational deterioration; positive symptoms are psychotic or manic states that may occur in the course of the dementing illness. It is further purposed that there is a window of vulnerability to psychosis or mania that occurs relatively early in the dementing process. Consequently, advancing dementia would be expected to be associated with remission of psychosis.

Cerebrospinal fluid and serum levels of neuron-specific enolase in patients with schizophrenia

Some patients with schizophrenia appear to have brain abnormalities, including enlarged third and lateral ventricles and reduced volumes of temporal lobe structures. These abnormalities could be attributed to a developmental abnormality or a neurodegenerative process. Neuron-specific enolase (NSE), a protein that is found primarily in neurons and neuroendocrine cells, has been used as an index of neuronal damage or degeneration. Levels of NSE in cerebrospinal fluid (CSF) and serum from 50 patients with acute and chronic schizophrenia were compared with those in normal and neurological control subjects. A double-antibody, solid phase iodinated radioimmunoassay was used to determine NSE levels. There was no evidence of elevated levels in patients with schizophrenia, whereas control subjects with neurological illnesses had increased levels of NSE in CSF. Because NSE is rapidly cleared from CSF, however, elevated levels could have been missed. Unmedicated patients tended to have lower levels than medicated patients.

Headaches and psychoactive substance use

A number of clinical reports have revealed an association between the use of alcohol and drugs and the onset or exacerbation of headaches. In order to investigate this association systematically and to examine the temporal relationship between onset of headaches and psychoactive substance use, we analyzed responses to a self-report questionnaire from 267 consecutive admissions to a three-week inpatient substance abuse treatment program. The response rate was 89.7%. The following characteristics were noted in the 236 respondents: 1) Over 89% reported having experienced some type of headache. 2) Headache-free individuals were significantly older than headache sufferers. 3) Women were much more likely to have migraine headaches than men. 4) Onset of migraines occurred prior to onset of substance use, while onset of tension headaches occurred after onset of substance use. Although associational data must be interpreted with caution, an intriguing hypothesis compatible with the finding is that migraines may play a role in the genesis of substance use, while substance use may play a role in the genesis of tension headaches.

The nucleus basalis of Meynert, senile plaques, and intellectual impairment in schizophrenia

The large, hyperchromic, cholinergic neurons of the nucleus basalis of Meynert (nbM) and the presence of senile plaques were quantified in postmortem brain tissue from 10 intellectually impaired schizophrenic patients, seven intellectually intact schizophrenic patients, seven control subjects, and three patients with Alzheimer's disease. The two groups of schizophrenic patients did not show any significant differences when compared with the control group in nbM cell density or in plaque frequency. The Alzheimer's disease patients showed the expected decrease in nbM neuronal density and increase in plaques compared with the controls. The data suggest that compromised cognitive function in schizophrenia is not associated with diffuse neuropathology of the basal forebrain cholinergic system.

Mania in AIDS: clinical significance and theoretical considerations

Cases of mania associated with acquired immune deficiency syndrome (AIDS) are reviewed in an attempt to elucidate patterns that may be helpful in guiding treatment, determining prognosis, and understanding pathophysiology. Fourteen well-described cases in the English language literature were critically reviewed. Data was collected regarding chronological appearance of signs and symptoms, specific psychiatric symptoms, associated neurologic and cognitive function, objective testing of brain structure and function, and outcome. When mania or hypomania occur in the setting of a human immunodeficiency virus (HIV) infection, it frequently occurs once and does not recur. AIDS-associated manic states are adequately responsive to available antimanic agents, however, AIDS patients may be more prone to deleterious side effects. Although mania or hypomania may be the presenting complaints that lead to the discovery of human immunodeficiency virus (HIV) seropositive status, mania tends to occur in people exhibiting signs of immunodeficiency as is exemplified, in the sample, by death occurring within six months of the psychiatric presentation in nearly a quarter of the patients. It is hypothesized that AIDS-related mania and agitated psychosis may be related to increased intracellular free calcium.

Hyperemesis gravidarum as conversion disorder

Psychosocial factors have long been believed to be important in the pathogenesis of emesis gravidarum (morning sickness) and hyperemesis gravidarum (HG). Although this has been confirmed during extensive studies over the last 30 years, HG has never been described as a conversion reaction. We describe two women presenting with hyperemesis who clearly fulfill diagnostic criteria for conversion. We suggest that strong psychodynamic conflicts are expressed by this potentially dangerous symptom in a subset of individuals and that dynamic interventions have a role in treating certain patients with HG.

Calcium channel blockers in affective illness: role of sodium-calcium exchange

Available evidence suggests that verapamil and perhaps other calcium channel blockers are effective in treating mania but not unipolar depression. This article briefly reviews the clinical experience and reexamines potential mechanisms. It is proposed that antimanic efficacy is primarily related to inhibition of sodium-calcium counterexchange rather than calcium channel blockade.

Lithium

Lithium utility and toxicity are reviewed. Lithium continues to be the most useful agent available for the prophylaxis and treatment of bipolar illness. Lithium augmentation of antidepressants is useful in treatment-resistant unipolar depression. Utility in other psychiatric disorders, such as schizoaffective, alcoholism, or aggressive behavior, is documented only when a significant affective component coexists. In internal medicine, lithium has proven useful in the prophylaxis of cluster headaches and in ameliorating chemotherapy-induced neutropenia. Other miscellaneous uses in both psychiatry and medicine have been anecdotally reported and are reviewed. However, the use of lithium may be limited by acute and chronic toxic side effects. Acute toxicity almost always manifests as central nervous system (CNS) dysfunction, and the degree of toxicity usually parallels the extent of CNS dysfunction. Chronic toxic manifestations effect cardiac, renal, and endocrine systems. In fetu exposure may be teratogenic.

Delusional misidentification involving the self

The delusion of replacement of one's self by a double or imposter is a feature of two delusional misidentification syndromes. In the syndrome of subjective doubles, the self-delusional misidentification syndromes. In the syndrome of subjective doubles, the self-delusion is the sole delusion of doubles. In the Capgras syndrome, the delusion of a self-double is infrequently reported; however, when it is reported, self-replacement is always accompanied by delusions of duplication of other people and sometimes of places. We review all such cases reported since 1900 and highlight the variety of presentations.

Aspartame: clinical update

Since the introduction of aspartame into the American food supply in 1981, it has grown to become the most widely used and accepted artificial sweetener. However, recent published and unpublished reports of headaches, seizures, blindness, and cognitive and behavioral changes with long-term, high-dose aspartame may be cause for concern. Physician awareness of the present clinical and research status of aspartame is important.

Cervical myelopathy secondary to movement disorders: case report

Involuntary cervical movements that result in cervical spondylosis and secondary myelopathy have not been adequately emphasized in the literature. We present two patients with cerebral palsy and long histories of involuntary movements who developed cervical myelopathy. We use these illustrative cases to emphasize that in the presence of underlying neurological symptoms and signs due to advanced cerebral palsy, any recent worsening should provoke a higher index of suspicion for myelopathy. The mechanics of neck movements and surgical treatment are discussed.