Disturbances in consciousness - Part - I - Syncope

Syncope and Syncoptic episode.

Syncope is episodic loss of consciousness associated with loss of postural tone. The pathophysiology is distinct from that of seizures and involves global hypoperfusion[1] of the brain or brainstem.

In otherwords Syncope is the medical term for fainting, a sudden, usually temporary, loss of consciousness generally caused by insufficient oxygen in the brain either through cerebral hypoxia[2] or through hypotension, or possibly for other reasons. Typical symptoms progress through dizziness, clamminess of the skin, a dimming of vision or greyout, possibly tinnitus, complete loss of vision, weakness of limbs to physical collapse. These symptoms falling short of complete collapse, or a fall down, may be referred to as a syncoptic episode.

A pre- or near-syncope is diagnosed if the individual can remember events during the loss of consciousness (i.e., reports remembering dizziness, blurred vision, and muscle weakness, and the fall previous to hitting his or her head and losing consciousness). If the individual remembers feeling dizzy and loss of vision, but not the fall, then it is considered a syncoptic episode.

Vasovagal Syncope (Simple Faints)

Vasovagal syncope occurs in all age groups. Precipitating factors include emotional stimulation, pain, the sight of blood, fatigue, medical instrumentation, blood loss, or prolonged motionless standing. Vagally mediated decreases in arterial blood pressure and heart rate combine to produce CNS hypoperfusion and subsequent syncope.

Vasovagal episodes generally begin while the patient is in a standing or sitting position and only rarely in a horizontal position. A prodrome lasting 10 seconds to a few minutes usually precedes syncope and can include lassitude, light-headedness, nausea, pallor, diaphoresis, salivation, blurred vision, and tachycardia. The patient, who then loses consciousness and falls to the ground, is pale and diaphoretic and has dilated pupils. Bradycardia[3] replaces tachycardia[4] as consciousness is lost. During unconsciousness, abnormal movements may occur, particularly if the patient remains relatively vertical; these are mainly tonic or opisthotonic, but seizurelike tonic–clonic activity is occasionally seen, which can lead to a misdiagnosis of epilepsy. Urinary incontinence may also occur.

The patient recovers consciousness very rapidly (seconds to a few minutes) after assuming the horizontal position, but residual nervousness, dizziness, headache, nausea, pallor, diaphoresis, and an urge to defecate may be noted.

Syncope may recur, especially on standing within the next 30 minutes.

Cardiovascular Syncope

A cardiovascular cause is suggested when syncope occurs with the patient in a recumbent position, during or after physical exertion, or in a patient with known heart disease. Loss of consciousness related to cardiac disease is most often due to an abrupt decrease in cardiac output with resultant cerebral hypoperfusion.

Such cardiac dysfunction can result from cardiac arrest, rhythm disturbances (either brady- or tachyarrhythmias), cardiac inflow or outflow obstruction, intracardiac right-to-left shunts, leaking or dissecting aortic aneurysms [5], or acute pulmonary embolus.

1. Cardiac Arrest

Cardiac arrest (ventricular fibrillation, or asystole) from any cause will result in loss of consciousness in 3–5 seconds if the patient is standing or within 15 seconds if the patient is recumbent. Seizure like activity and urinary and fecal incontinence may be seen as the duration of cerebral hypoperfusion increases.

2. Tachyarrhythmias

Cardiac arrhythmia is any of a group of conditions in which the electrical activity of the heart is irregular or is faster or slower than normal.Some arrhythmias are life-threatening medical emergencies that can cause cardiac arrest and sudden death. Arrhythmias that are due to fast, abnormal electrical activity can cause tachycardias that are dangerous. If the ventricles of the heart experience one of these tachycardias for a long period of time, there can be deleterious effects. Individuals may sense a tachycardia as a pounding sensation of the heart, known as palpitations. If a tachycardia lowers blood pressure it may cause lightheadedness or dizziness, or even fainting (syncope). If the tachycardia is too fast, the pump function of the heart is impeded, and rarely may lead to sudden death.Most tachycardias are not dangerous.

3. Bradyarrhythmias

Bradycardia, as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min.

Sinoatrial node disease may cause syncope with profound sinus bradycardia, prolonged sinus pauses, or sinus arrest with a slow atrial, junctional, or idioventricular escape rhythm. Patients should be promptly evaluated by a cardiologist, since a permanent pacemaker is necessary in many cases.

Complete heart block (third-degree atrioventricular block) is a common bradyarrhythmia producing syncope. Permanent atrioventricular conduction abnormalities are easily noted on a routine ECG, but intermittent conduction abnormalities may not be present on a random tracing. Patients with syncope and documented or suspected complete heart block should be promptly hospitalized. Patients with acute inferior myocardial infarctions are at high risk for atrioventricular block.

4. Cardiac Inflow Obstruction

Atrial or ventricular myxomas and atrial thrombi[6] usually present with embolic events, but they may also produce a left ventricular inflow or outflow obstruction that results in a sudden decrease in cardiac output, followed by syncope. Echocardiography can confirm the diagnosis. Surgical removal of the myxoma is indicated.

5. Cardiac Outflow Obstruction

Loss of consciousness from congenital or acquired severe aortic stenosis usually occurs following exercise, and is often associated with dyspnea, angina, and diaphoresis. The pathophysiology may involve acute left ventricular failure resulting in coronary hypoperfusion and subsequent ventricular fibrillation, or abrupt increases in left ventricular pressure that stimulate baroreceptors, leading to peripheral vasodilation.

6. Hypertrophic Cardomyopathy

Hypertrophic cardiomyopathy, or HCM, is a disease of the myocardium (the muscle of the heart) in which a portion of the myocardium[7] is hypertrophied (thickened) without any obvious cause. HCM's more important significance is as a cause of sudden unexpected cardiac death in any age group and as a cause of disabling cardiac symptoms. A cardiomyopathy is any disease that primarily affects the muscle of the heart. In HCM, the normal alignment of muscle cells is disrupted, a phenomenon known as ''myocardial disarray''. HCM also causes disruptions of the electrical functions of the heart.

7. Dissecting Aortic Aneurism

Aortic dissection is a tear in the wall of the aorta that causes blood to flow between the layers of the wall of the aorta and force the layers apart. Aortic dissection is a medical emergency and can quickly lead to death, even with optimal treatment.

Approximately 5–10% of patients with acute aortic dissections present with isolated syncope; other neurologic abnormalities may or may not be present. In 15% of patients, the dissection is painless.

8. Pulmonary Hypertension and Pulmonary Embolus

In medicine, pulmonary hypertension (PH) is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion. Pulmonary hypertension can be a severe disease with a markedly decreased exercise tolerance and right-sided heart failure.

Syncope is the presenting symptom in approximately 20% of patients experiencing a massive pulmonary embolus.

Cerebrovascular Syncope

Cerebrovascular disease is an often suspected but actually uncommon cause of episodic unconsciousness.

Cerebral causes

1. Basilar Artery Insufficiency

Basilar artery transient ischemic attacks usually occur after the sixth decade. The symptom complex of diplopia, vertigo, dysphagia, dysarthria, various sensory or motor symptoms, drop attacks, and occipital headaches suggests diffuse brainstem ischemia.  Attacks are typically sudden in onset and brief in duration (seconds to minutes), but when consciousness is lost, recovery is frequently prolonged (30–60 minutes or longer).

2. Sunbclavian Steal Syndrome

The subclavian steal syndrome results from subclavian or innominate artery stenosis that causes retrograde blood flow in the vertebral artery, with subsequent brainstem hypoperfusion. Stroke is rare. If this diagnosis is suspected, arteriography and surgical correction may be indicated.

3. Migraine

Syncope occurs in 10% of patients with migraine during the headache, often on rapid rising to a standing position, suggesting that loss of consciousness is due to orthostatic hypotension.

4. Takayasu Disease

Takayasu disease is a panarteritis of the great vessels that is most common in Asian women. Symptoms of cerebral hypoperfusion such as impaired vision, confusion, and syncope are often prominent. Precipitating factors include exercise, standing, or head movement. Examination reveals decreased or absent brachial pulses with low blood pressures in both arms.

5. Carotid Sinus Syncope

Carotid sinus syncope is uncommon. Men are affected twice as often as women, and most affected individuals are older than 60 years. Pressure on the carotid sinus by a tight collar, a neck mass, enlarged cervical lymph nodes, or a tumor causes vagal stimulation, which inhibits the cardiac sinoatrial and atrioventricular nodes and reduces sympathetic vascular tone. The resultant bradycardia or systemic hypotension may then produce syncope; pure cardioinhibitory or vasodepressor syncope also occurs.

Orthostatic Hypotension

Orthostatic hypotension occurs more often in men than in women and is most common in the sixth and seventh decades. It may, however, appear even in teenagers. Loss of consciousness usually occurs upon rapidly rising to a standing position, standing motionless for a prolonged period (especially following exercise), and standing after prolonged recumbency (especially in the elderly).

Numerous conditions can produce orthostatic hypotension, which generally results from either reduced blood volume or autonomic nervous system dysfunction. The latter may be due to sympathetic drugs, autonomic neuropathy, or CNS disorders affecting sympathetic pathways in the hypothalamus, brainstem, or spinal cord.

Miscellaneous Causes Of Syncope

1. Hyperventilation Syncope

Hyperventilation is a frequent cause of faintness or dizziness but rarely culminates in syncope. Common symptoms include light-headedness, shortness of breath, circumoral numbness and tingling, and muscular twitching. Pathophysiologically, hypocapnia produces cerebral vasoconstriction and results in CNS hypoperfusion. Patients are usually between 20 and 40 years of age, and women are affected far more frequently than men.

Symptoms commonly occur in the lying position, which can be diagnostically helpful. Patients often report prolonged unconsciousness, but upon close questioning this rarely proves to be true. Hyperventilation at the examiner’s request often reproduces the symptoms.

2. Cough Syncope

Cough (tussive) syncope occurs chiefly in middle-aged men with chronic obstructive pulmonary disease but has also been reported in children. Coughing, which need not be prolonged, immediately precedes unconsciousness. Cough syncopy may occur while the patient is supine. Prodromal symptoms are absent, and the duration of unconsciousness is brief—often only a few seconds.

3. Micturition Syncope

Micturition syncope occurs almost exclusively in men, probably because of the standing position for urination. Episodes can occur immediately before, during, or after micturition. They are more likely to occur at night following the prolonged recumbency of sleep and are due to peripheral pooling of blood plus a vagally induced bradycardia. Urination in a sitting position usually eliminates the symptoms.

4. Glossopharyngial Neuralgia

Glossopharyngeal neuralgia is a rare syndrome of intermittent, agonizing paroxysmal pain localized to the tonsil-lar pillar or occasionally to the external auditory meatus. The pain is triggered by contact with or movement of the tonsillar pillars, especially during swallowing or talking. Syncope occurs as a consequence of the activation of a glossopharyngeal-vagal reflex arc, producing a transient bradyarrhythmia with resultant cerebral hypoperfusion.

5. Psycogenic Syncope

Psychogenic syncope is a diagnosis of exclusion and is often made erroneously. Suggestive features are lack of any prodrome, possible secondary gain, bizarre postures and movements, lack of pallor, and a prolonged period of apparent unresponsiveness. Most patients are young or have a well-documented history of conversion disorder. Without such a history, diagnosis after the third decade is suspect.

Diagnostic approach

Clinical tests

If one is suffering from syncope, there are many underlying causes that may be contributing to the episodes. It is important to understand that there is no master list of tests that are currently being used to diagnose the underlying cause(s). However, there are some common diagnostic tests for fainting.

Blood Test : A hemoglobin count may indicate anemia or blood loss. However, this has been shown to be useful in only about 5% of patients being evaluated for fainting.

Electrocardiogram : An electrocardiogram (ECG) records the electrical activity of your heart. It is estimated that from 20%-50% of patients will have an abnormal ECG. However, while an ECG may identify conditions such as atrial fibrillation, heart block, or a new or old heart attack, it typically does not provide a definite diagnosis for the underlying cause for fainting.

Holter monitor testing : Sometimes, one may be asked to wear a Holter monitor. This is a portable ECG device that can record the wearer's heart rhythms during daily activities over an extended period of time. Since fainting usually does not occur upon command, a Holter monitor can provide a better understanding of the heart's activity during fainting episodes.

Tilt table test : This is perhaps the most common test performed for syncope. Though it can be helpful, the purpose is to induce a fainting episode, and, thus, is not necessarily conclusive in why this occurs.

Management

Recommended treatment involves returning blood to the brain by positioning the person on the ground, with legs slightly elevated or leaning forward and the head between the knees. As the dizziness and the momentary blindness passes, the person may experience a brief period of visual disturbances in the form of phosphenes, sudden sore throat, nausea, and general shakiness. After the symptoms have passed, sleep is recommended.

Treatment

Treatment  depends on specific cause of the condition. The cause is treated for long term management and relief.

Meaning of medical terms

1. Perfusion : perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue.
2. Cerebral hypoxia : Cerebral hypoxia refers to deprivation of oxygen supply to brain tissue.
3. Bradycardia : Bradycardia, as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min.
4. Tachycardia : Tachycardia is a form of cardiac arrhythmia which refers to a rapid beating of the heart. By convention the term refers to heart rates greater than 100 beats per minute in the adult patient.
5. Aneurysm : An aneurysm (or anneurism) is a localized, blood-filled dilation (bulge) of a blood vessel caused by disease or weakening of the vessel wall.
6. Thrombi : A thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system (i.e. clotting factors). A thrombus is physiologic in cases of injury, but pathologic
7. Myocardium :  Myocardium is the muscular tissue of the heart.

References

http://en.wikipedia.org/wiki/Syncope_(medicine)
Clinical Neurology, 7th Edition, David A Greenberg, Michael J. Aminoff

Between Life and Death - Part III - Persistant Vegetative State

Persistant vegetative state (PVS)

A persistent vegetative state (PVS) is a condition of patients with severe brain damage in whom coma has progressed to a state of wakefulness without detectable awareness.

As opposed to brain death, PVS is not recognized as death in any legal system. This legal grey area has led to several court cases involving people in a PVS, those who believe that they should be allowed to die, and those who are equally determined that, if recovery is possible, care should continue.

History

The syndrome was first described in 1940 by Ernst Kretschmer who called it ''apallic Syndrome''.

The term ''persistent vegetative state'' was coined in 1972 by Scottish spinal surgeon Bryan Jennett and American neurologist Fred Plum to describe a syndrome that seemed to have been made possible by medicine's increased capacities to keep patients' bodies alive.

Description

The vegetative state is a chronic or long-term condition. This condition differs from a persistent vegetative state (PVS, a state of coma that lacks both awareness and wakefulness) since patients have awakened from coma, but still have not regained awareness.

In the vegetative state patients can open their eyelids occasionally and demonstrate sleep-wake cycles. They also completely lack cognitive function. The vegetative state is also called coma vigil.

The continuing vegetative state describes a patient's diagnosis prior to confirmation of the permanence of the condition.  The permanent vegetative state occurs when the vegetative state is deemed permanent; a prediction is being made that the patient will never recover awareness. This prediction cannot be made with absolute certainty. However, the chances of regaining awareness diminish considerably as the time spent in the vegetative state increases.

Signs and Symptoms

1. Most PVS patients are unresponsive to external stimuli and their conditions are associated with different levels of consciousness.
2. PVS patients often open their eyes, whereas patients in a coma subsist with their eyes closed.
3. PVS patients' eyes might be in a relatively fixed position, or track moving objects, or move in a ''disconjugate'' (i.e. completely unsynchronised) manner.
4. They may experience sleep-wake cycles, or be in a state of chronic wakefulness.
5. They may exhibit some behaviors that can be construed as arising from partial consciousness, such as grinding their teeth, swallowing, smiling, shedding tears, grunting, moaning, or screaming without any apparent external stimulus.

Causes

There are three different causes of PVS:

1. Brain injuries which may be either acute and traumatic, or non-traumatic;
2. Degenerative and metabolic brain disorders, and severe congenital abnormalities of the central nervous system.
3. Toxins such as uremia, ethanol, atropine, opiates, lead, substance abuse, colloidal silver.

Misdiagnoses

One study of 40 patients in the United Kingdom reported that 43% of those patients classified as in a PVS were misdiagnosed and another 33% able to recover whilst the study was underway.  Some cases of PVS may actually be cases of patients being in an undiagnosed minimally conscious state.

Recovery Possibility

Many patients emerge spontaneously from a vegetative state within a few weeks.

Possible Treatment and Cures

As of April 2007, no treatment for vegetative state exists that would satisfy the efficiency criteria of evidence-based medicine. Several methods have been proposed which can roughly be subdivided into four categories: pharmacological methods, surgery, physical therapy, and various stimulation techniques.

Pharmacological therapy mainly uses activating substances such as tricyclic antidepressants or methylphenidate. Promising results have been reported on dopaminergic drugs, particularly amantadine.

Surgical methods such as deep brain stimulation are rarely used.

Stimulation techniques include sensory stimulation, sensory regulation, music and musicokinetic therapy, social-tactile interaction, etc.

References

http://en.wikipedia.org/wiki/Persistent_vegetative_state

Medical Encylopedia for MobileReference

Between Life and Death - Part II - Locked-in syndrome

Locked-in syndrome

Locked-In syndrome is a condition in which a patient is aware and awake, but cannot move or communicate due to complete paralysis of nearly all voluntary muscles in the body. It is the result of a brain stem lesion in which the ventral part of the pons is damaged. The condition has been described as 'the closest thing to being buried alive'.Locked-in alive'.Locked-in syndrome is also known as Cerebromedullospinal Disconnection, De-Efferented State, Pseudocoma, and ventral pontine syndrome.

Clinical Presentation

• Unable to speak
• unable to move the limbs
• Awareness and consciousness preserved
• Able to open eyes and move them and blink, in order to try to communicate.

Causes

Locked-in syndrome is caused by damage to specific portions of the lower brain and brainstem with no damage to the upper brain.

Possible causes of locked-in syndrome include:
- Traumatic brain injury
- Diseases of the circulatory system
- Medication overdose
- Damage to nerve cells, particularly destruction of the myelin sheath, caused by disease (e.g. central pontine myelinolysis secondary to rapid correction of hyponatremia).
- A stroke or brain hemorrhage

Treatment

There is no standard treatment for Locked-In syndrome, nor is there a cure. Stimulation of muscle reflexes with electrodes (Neuromuscular stimulation) has been known to help patients regain some muscle function.
Other courses of treatment are often symptomatic.

Progress

It is extremely rare for any significant motor function to return. The majority of locked-in syndrome patients do not regain motor control, but devices are available to help patients communicate.

References

Medical Encyclopedia from MobileReference
Clinical Neurology, Graeme J Hankley MD, FRCP (Lond), FRCP(Edin), FRACP, Joana M Wardlaw MBchB, MD, FRCP, FRCR
Clinical Neurology, 7e, Roger P. Simson, MD, David A. Greenberg, MD, PHD

Between Life and Death - Part I - Coma

Coma

In medicine, a coma is a profound state of unconsciousness. A person in a coma cannot be awakened, fails to respond normally to pain, light or sound, does not have sleep-wake cycles, and does not take voluntary actions. A person in a state of coma can be described as comatose.

Understanding the condition

Coma is a sleeplike state in which the patient makes no purposeful response to the environment and from which he or she cannot be aroused. The eyes are closed and do not open spontaneously. The patient does not speak, and there is no purposeful movement of the face or limbs or non-purposeful reflex movements mediated through spinal cord or brainstem pathways.

Underlying causes

Coma results from a disturbance in the function of either the brainstem reticular activating system above the midpons or of both cerebral hemispheres, since these are the brain regions that maintain consciousness.

The severity and mode of onset of coma depends on the underlying cause. For instance, deepening hypoglycemia (low blood sugar) or hypercapnia (increased carbon dioxide levels in the blood) initially cause mild agitation and confusion, then progress to obtundation, stupor and finally complete unconsciousness. In contrast, coma resulting from a severe traumatic brain injury or subarachnoid hemorrhage can be instantaneous. The mode of onset may therefore be indicative of the underlying cause.

The most crucial aspect of the history is the time over which coma develops. In the absence of precise details about the mode of onset, information about when the patient was last seen in an apparently normal state may assist in establishing the time course of the disease process.

1. A sudden onset of coma suggests a vascular origin, especially a brainstem stroke or subarachnoid hemorrhage.

2. Rapid progression from hemispheric signs, such as hemiparesis, hemisensory deficit, or aphasia, to coma within minutes to hours is characteristic of intracerebral hemorrhage.

3. A more protracted course leading to coma (days to a week or more) is seen with tumor, abscess, or chronic subdural hematoma.

4. Coma preceded by a confusional state or agitated delirium, without lateralizing signs or symptoms, is probably due to a metabolic derangement.

Glasgow Coma Scale

The Glasgow Coma Scale or GCS, sometimes also known as the Glasgow Coma Score is a neurological scale which aims to give a reliable, objective way of recording the conscious state of a person, for initial as well as continuing assessment. The scale was published in 1974 by Graham Teasdale and Bryan J. Jennett, professors of neurosurgery at the University of Glasgow. The scale comprises three tests: eye, verbal and motor responses. GCS is used as part of several ICU scoring systems to assess the status of the central nervous system.

Progress

Outcomes range from recovery to death. Comas generally last a few days to a few weeks, rarely more than 2 to 5 weeks but it can last as long as several years. Rarely it lasts longer but it is possible.

According to the Guinness Book of Records, the longest period spent in coma was by Elaine Esposito. She did not wake up after being anaesthetized for an appendectomy on August 6, 1941, at age 6. She died on November 25 1978 at age 43 years 357 days, having been in a coma for 37 years 111 days.

People may emerge from a coma with a combination of physical, intellectual and psychological difficulties that need special attention. Recovery usually occurs gradually patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases.

References

Medical Encyclopedia from Mobile Reference

Clinical Neurology, 7e, Roger P. Simson, MD, David A. Greenberg, MD, PHD