STUDY - Technical - New Dacian's Medicine
Acute
Confusion and Coma (3)
Translation Draft
We're continuing with the general neurological evaluation. An accurate description of spontaneous and provoked movements is of great importance in determining the level of neurological dysfunction. The patient's condition should be observed first without the intervention of the examiner.
The nature of breaths and spontaneous movements are observed. Patients who writhe in bed, put their hands to their faces, cross their legs, cap, swallow, cough or jam are almost alert. The only sign of seizures may be the simple twisting of a leg, finger or facial muscle. External torsion of a foot at rest or absence of movement on one side are indications of hemiparesis.
The terms rigidity by decoration or decerebrary or "postural" are used to describe stereotypical movements of the arms and legs, which occur spontaneously or are caused by sensory stimulation.
The flexion of the elbows and wrists and the supination of the forearm (decortication) suggest a serious bilateral condition in the hemispheres above the brain stem, while the extension of the elbows and wrists with pronation (decerebration) suggests damage to the mesencephalus or caudal diencephalus.
The extension of the arm with minimal flexion of the foot or atonet legs were associated with damage to the lower bridge. However, these terms have been adapted from animal experiments and cannot be applied with the same precision in the case of comet in humans. Acute lesions of any type, regardless of their location, lead to the extension of the limbs and almost all initial extensor positions become flexors with the passage of time, so that only the posture of the limbs cannot be the one that gives an exact anatomical localization of the lesion.
Metabolic coma, especially after acute hypoxia, can also generate strong spontaneous extensor stiffness (decerebration). The posture can coexist with a voluntary movement of the limbs, usually denoting an subtotal damage to the engine system. Multifocal myoclonia is almost always an indication of metabolic disturbance, especially nitrogenemia, anoxia or drug ingestion. In a sober, confused patient, bilateral asterixis is a sign of metabolic encephalopathy or drug ingestion.
Another important milestone is the movements caused and the level of stiffness. If the patient is not awakened when spoken to, a sequence of increased intensity stimuli is used to determine the best level of patient alertness and optimal motor response of each member.
Nasal arousal with a cotton swab is a powerful wake-up stimulus. Pressing the knees or bone protrusions is preferred as a gentle form of application of painful stimuli. The pinching of the skin of the face, chest or limbs can cause bruising and is not desirable.
The response to painful stimuli must be accurately assessed. The movement to avoid limb abduction is usually intentional and denotes an intact corticospinal system for that limb. Stereotypical positioning as a result of stimulation of a limb indicates severe dysfunction of the corticospinal system.
Abduction and flexion of the stimulated limbs can constitute reflex movements and involve an impairment of the corticospinal system. Short clonic movements or twisting movements of the limb occur at the end of the tatoons of the extension position and should not be confused with convulsions.
The reflexes (signs) of the brain stem are the key to locating coma lesions. As a rule, coma associated with normal brain stem function indicates extensive bilateral hemispheric dysfunction or lesion.
The reflexes of the brain stem that allow for convenient examination are the pupillary photomotor reflex, eye movements, both spontaneous and provoked, and respiratory pattern. The pupil reaction must be examined with a bright, diffuse light and if the response is absent, it must be confirmed with a amplifier lens.
The pupil reaction to light less than 2 mm is often difficult to assess. Round, symmetricalreactive pupils (2.5 to 5 mm in diameter) usually exclude injury to the mesencephalus as a cause of the comet. A dilated pupil (greater than 5 mm) and areactive or with low reactivity usually occurs under the conditions of the presence of intrinsic lesion in the mesencephalus (on the same side) or, more often, is secondary to compression or stretching of the third nerve by the side effects of a tumor mass or by moving the brain horizontally.
Unilateral pupil dilation usually denotes an ipsilateral and rarely contralateral mass, possibly by compression of the metencephalus or the third nerve on the opposite tentorial edge. An oval or slightly eccentric pupil often accompanies the beginning of mesencephalus/ third nerve compression. Bilaterally dilated and areactive pupils indicate a severe lesion in the mesencephalus, usually by a compression secondary to transtentorial hernia or by ingestion of anticholinergic drugs.
The use of midriatic eye drops by another previous examiner, self-administration by the patient or direct eye trauma may cause misleading pupil dilation. Bilateral reactive and small pupils, but not as much as the tip of the pin (1 to 2.5 mm) are most commonly observed in metabolic encephalopathy or following profound bilateral hemispheric lesions, such as hydrocephalus or talamic haemorrhage.
This has been attributed to the dysfunction of the ecerences of the sympathetic nervous system from the posterior hypothalamus. Very small but reactive pupils (less than 1 mm) denote a narcotic or barbiturate overdose, but also occur in case of extensive bilateral pontine acute injury, usually by hemorrhage.
They are identified by response to naloxone and by the presence of reflex movements of the eye. The small one-sided pupil in Horner syndrome is detected by not dilating it in the dark. It is rare in coma and can be seen ipsilaterally in a large cerebral hemorrhage affecting the thalamus. The palpebral tone, tested by lifting the eyelids, palpation of the opening resistance and closing speed, is gradually reduced as the coma progresses.
Eye movements are the second basic element in the physical diagnosis of the comet, because their examination allows exploration of a large portion of the brain stem. The eyes are first observed by lifting the eyelids and noticing the resting position and spontaneous movements of the eyeballs. Horizontal divergence of the eyes at rest is normally observed in dizziness.
As the patient wakes up or falls into a deep coma, the eye axes become parallel again. An abdus eye at rest indicates the paresis of the lateral right (weakness) due to an injury to the sixth nerve and when bilateral, it is often a sign of increased intracranial pressure.
An abdus eye at rest, often accompanied by ipsilateral pupil dilation, indicates the paresis of the medial right due to the dysfunction of the third nerve. With a few exceptions, vertical separation of the eye axes or oblique deviation results in the case of pontine or cerebellar lesions. Spontaneous eye movements in coma generally take the form of horizontally conjugated stray gaze. This movement exonerates the mesencephalus and the bridge and has the same meaning as normal reflex eye movements.
Vertical downward slower movements are observed under specific conditions. "Ocular pendulum" describes a brisk downward and slow upward movement of the eyeballs, associated with the loss of horizontal movements, diagnosing a bilateral pontine lesion.
"Ocular immersion" is a slow, slow, downward movement followed by a faster upward movement in patients with normal horizontal reflex and denotes a diffuse anoxic lesion in the cerebral cortex. The eyes may rotate down and inside in the case of thalamic lesions and upper mesencephalus.
The responses of "doll's eyes" or oculocephalic are reflex movements tested by moving the head from side to side or vertically, first slowly, then suddenly (eye movements are described as taking place in the opposite direction of head movement).
These responses are generated by the mechanisms of the brain stem originating in the labyrinth and cervical proprioceptors. They are normally repressed in patients aware of visual fixation mediated by the cerebral hemispheres, but occur as the hemispheres are repressed or inactive. Neural pathways for horizontal reflex eye movements require the integrity of the region surrounding the nucleus of the sixth nerve and is combined with the third contralateral nerve through the median longitudinal beam (FLM).
Two different informations can be obtained from the reflex movements of the eye. First in a coma resulting from damage to both hemispheres or from drug or metabolic depression, the eyes move slightly or "lejer" from side to side in the opposite direction to the direction of rotation of the head. The ease with which the eyes move towards the opposite side reflects the disinhibition of the reflexes of the brain stem by damage to the cerebral hemispheres.
Secondly, conjugated oculocephalic movements demonstrate the integrity of the cerebral trunk paths extending from the upper cervical marrow and bulb, where the proprioceptive and vestibular transmission of the rotation of the head originates, to the mesencephalus at the level of the third nerve. Thus, complete and conjugated movements induced by oculocephal maneuvers demonstrate the integrity of a large segment of the brain stem and help in eliminating the possibility of a lesion in the brain stem as a cause of the comet.
Incomplete ocular abduction indicates a lesion in the ipsilateral mesencephalus (third nerve) or a lesion in the transmission pathway that mediates the reflex movements of the eye in the FLM (e.g. internuclear ophthalmoplegia).
A damage to the third nerve is usually associated with a dilated pupil and horizontal eye divergence at rest, while FLM destruction is not related to pupillary function and leaves the eyeball in its primary position. Abduction of the eyeballs is in itself more difficult to obtain than abstraction, and subtle anomalies in the "doll's eye" maneuver must be interpreted carefully.
Caloric stimulation of the vestibular apparatus (oculovestibular response) is useful in the oculocephalic test and acts as a stronger stimulus of reflex movements of the eye, but fundamentally providing the same information. Irrigation of the external auditory canal with cold water causes convection currents in the endolymph of the inner ear labyrinth.
An intact path of the brain stem from the labyrinth to the oculomotor nucleus is indicated, with variable latency, by a deflection of both eyes (lasting 30 to 120 seconds) on the side of irrigation with cold water. Therefore, conjugated bilateral eye movements have the same significance as complete oculocephalic responses.
If the cerebral hemispheres are intact, as happens in a hysterical coma, then a rapid corrective conjugate movement is generated from the tonic deviation. The absence of this rapid, rhythmic phase, similar to the nystagmus, signifies a lesion in the cerebral hemispheres or their suppression.
The conjugated horizontal ocular deviation at rest or incomplete eye movements conjugated with the rotation of the head indicates a bridge injury on the side of the paresis with the lost gaze or damage to the frontal lobe on the opposite side. This phenomenon can be summed up by the following aphorism: "The eyes look towards the hemispheric lesion and away from the lesion of the brain stem".
It is usually possible to remove the ocular deviation with damage to the frontal lobe by oculocephalic testing. Crises can also cause the opposite eye deviation with rhythmic, spastic movements on the lost-looking side. On rare occasions, the eyes may, paradoxically, abandon the part of a deep hemispheric lesion ("eyes that look wrong").
In hydrocephalus with the dilation of the third ventricle, the eyeballs frequently rest below the horizontal meridian. Two types of rhythmic eye movements may occur in stupor or coma. Eye myoclonia is a fast, horizontal nistagmus, usually associated with a similar movement of the palate and due to injury to the central tegmental beam, a longitudinal tract in the brain stem. Opsoclonus is an intermittent, spasmodic, irregular movement with variable direction resulting from cerebellar lesions.
A major trap in the diagnosis of coma can occur when reflex eye movements are suppressed medicinally. Then the eyes move as the head moves, as if they were fixed on the spot, thus falsely suggesting an anatomical injury to the brain stem. Overdoses of phenytoin, tricyclic antidepressants and barbiturates are commonly involved, and occasionally alcohol, phenothiazines, diazepam and neuromuscular blockers such as pancuronium.
The presence of normal pupil size and light reaction will distinguish most drug-induced comets from comets produced by damage to the brain stem. Small pupils (1 - 3 mm) and areactive may occur in the presence of a high serum level of barbiturates or secondary hydrocephalus.
Although corneal reflexes are rarely useful on their own, they may be additional signs of abnormalities in eye movements, as they also depend on the integrity of the pontine paths. Touching the cornea with a cotton swab, a response consisting of a short bilateral closure of the eyelid can be observed.
The corneal response may be lost if the reflex links between the fifth and sixth cranial nerve inside the bridge are affected. The normal efferent response is bilateral, with the closure of both eyelids. CNS depressant drugs decrease or eliminate corneal responses soon after paralyzing reflex eye movements but before the pupil becomes areactive in light.
Tomorrow... we discuss the respiratory patterns associated with these signs of the disease.
We're continuing with the general neurological evaluation. An accurate description of spontaneous and provoked movements is of great importance in determining the level of neurological dysfunction. The patient's condition should be observed first without the intervention of the examiner.
The nature of breaths and spontaneous movements are observed. Patients who writhe in bed, put their hands to their faces, cross their legs, cap, swallow, cough or jam are almost alert. The only sign of seizures may be the simple twisting of a leg, finger or facial muscle. External torsion of a foot at rest or absence of movement on one side are indications of hemiparesis.
The terms rigidity by decoration or decerebrary or "postural" are used to describe stereotypical movements of the arms and legs, which occur spontaneously or are caused by sensory stimulation.
The flexion of the elbows and wrists and the supination of the forearm (decortication) suggest a serious bilateral condition in the hemispheres above the brain stem, while the extension of the elbows and wrists with pronation (decerebration) suggests damage to the mesencephalus or caudal diencephalus.
The extension of the arm with minimal flexion of the foot or atonet legs were associated with damage to the lower bridge. However, these terms have been adapted from animal experiments and cannot be applied with the same precision in the case of comet in humans. Acute lesions of any type, regardless of their location, lead to the extension of the limbs and almost all initial extensor positions become flexors with the passage of time, so that only the posture of the limbs cannot be the one that gives an exact anatomical localization of the lesion.
Metabolic coma, especially after acute hypoxia, can also generate strong spontaneous extensor stiffness (decerebration). The posture can coexist with a voluntary movement of the limbs, usually denoting an subtotal damage to the engine system. Multifocal myoclonia is almost always an indication of metabolic disturbance, especially nitrogenemia, anoxia or drug ingestion. In a sober, confused patient, bilateral asterixis is a sign of metabolic encephalopathy or drug ingestion.
Another important milestone is the movements caused and the level of stiffness. If the patient is not awakened when spoken to, a sequence of increased intensity stimuli is used to determine the best level of patient alertness and optimal motor response of each member.
Nasal arousal with a cotton swab is a powerful wake-up stimulus. Pressing the knees or bone protrusions is preferred as a gentle form of application of painful stimuli. The pinching of the skin of the face, chest or limbs can cause bruising and is not desirable.
The response to painful stimuli must be accurately assessed. The movement to avoid limb abduction is usually intentional and denotes an intact corticospinal system for that limb. Stereotypical positioning as a result of stimulation of a limb indicates severe dysfunction of the corticospinal system.
Abduction and flexion of the stimulated limbs can constitute reflex movements and involve an impairment of the corticospinal system. Short clonic movements or twisting movements of the limb occur at the end of the tatoons of the extension position and should not be confused with convulsions.
The reflexes (signs) of the brain stem are the key to locating coma lesions. As a rule, coma associated with normal brain stem function indicates extensive bilateral hemispheric dysfunction or lesion.
The reflexes of the brain stem that allow for convenient examination are the pupillary photomotor reflex, eye movements, both spontaneous and provoked, and respiratory pattern. The pupil reaction must be examined with a bright, diffuse light and if the response is absent, it must be confirmed with a amplifier lens.
The pupil reaction to light less than 2 mm is often difficult to assess. Round, symmetricalreactive pupils (2.5 to 5 mm in diameter) usually exclude injury to the mesencephalus as a cause of the comet. A dilated pupil (greater than 5 mm) and areactive or with low reactivity usually occurs under the conditions of the presence of intrinsic lesion in the mesencephalus (on the same side) or, more often, is secondary to compression or stretching of the third nerve by the side effects of a tumor mass or by moving the brain horizontally.
Unilateral pupil dilation usually denotes an ipsilateral and rarely contralateral mass, possibly by compression of the metencephalus or the third nerve on the opposite tentorial edge. An oval or slightly eccentric pupil often accompanies the beginning of mesencephalus/ third nerve compression. Bilaterally dilated and areactive pupils indicate a severe lesion in the mesencephalus, usually by a compression secondary to transtentorial hernia or by ingestion of anticholinergic drugs.
The use of midriatic eye drops by another previous examiner, self-administration by the patient or direct eye trauma may cause misleading pupil dilation. Bilateral reactive and small pupils, but not as much as the tip of the pin (1 to 2.5 mm) are most commonly observed in metabolic encephalopathy or following profound bilateral hemispheric lesions, such as hydrocephalus or talamic haemorrhage.
This has been attributed to the dysfunction of the ecerences of the sympathetic nervous system from the posterior hypothalamus. Very small but reactive pupils (less than 1 mm) denote a narcotic or barbiturate overdose, but also occur in case of extensive bilateral pontine acute injury, usually by hemorrhage.
They are identified by response to naloxone and by the presence of reflex movements of the eye. The small one-sided pupil in Horner syndrome is detected by not dilating it in the dark. It is rare in coma and can be seen ipsilaterally in a large cerebral hemorrhage affecting the thalamus. The palpebral tone, tested by lifting the eyelids, palpation of the opening resistance and closing speed, is gradually reduced as the coma progresses.
Eye movements are the second basic element in the physical diagnosis of the comet, because their examination allows exploration of a large portion of the brain stem. The eyes are first observed by lifting the eyelids and noticing the resting position and spontaneous movements of the eyeballs. Horizontal divergence of the eyes at rest is normally observed in dizziness.
As the patient wakes up or falls into a deep coma, the eye axes become parallel again. An abdus eye at rest indicates the paresis of the lateral right (weakness) due to an injury to the sixth nerve and when bilateral, it is often a sign of increased intracranial pressure.
An abdus eye at rest, often accompanied by ipsilateral pupil dilation, indicates the paresis of the medial right due to the dysfunction of the third nerve. With a few exceptions, vertical separation of the eye axes or oblique deviation results in the case of pontine or cerebellar lesions. Spontaneous eye movements in coma generally take the form of horizontally conjugated stray gaze. This movement exonerates the mesencephalus and the bridge and has the same meaning as normal reflex eye movements.
Vertical downward slower movements are observed under specific conditions. "Ocular pendulum" describes a brisk downward and slow upward movement of the eyeballs, associated with the loss of horizontal movements, diagnosing a bilateral pontine lesion.
"Ocular immersion" is a slow, slow, downward movement followed by a faster upward movement in patients with normal horizontal reflex and denotes a diffuse anoxic lesion in the cerebral cortex. The eyes may rotate down and inside in the case of thalamic lesions and upper mesencephalus.
The responses of "doll's eyes" or oculocephalic are reflex movements tested by moving the head from side to side or vertically, first slowly, then suddenly (eye movements are described as taking place in the opposite direction of head movement).
These responses are generated by the mechanisms of the brain stem originating in the labyrinth and cervical proprioceptors. They are normally repressed in patients aware of visual fixation mediated by the cerebral hemispheres, but occur as the hemispheres are repressed or inactive. Neural pathways for horizontal reflex eye movements require the integrity of the region surrounding the nucleus of the sixth nerve and is combined with the third contralateral nerve through the median longitudinal beam (FLM).
Two different informations can be obtained from the reflex movements of the eye. First in a coma resulting from damage to both hemispheres or from drug or metabolic depression, the eyes move slightly or "lejer" from side to side in the opposite direction to the direction of rotation of the head. The ease with which the eyes move towards the opposite side reflects the disinhibition of the reflexes of the brain stem by damage to the cerebral hemispheres.
Secondly, conjugated oculocephalic movements demonstrate the integrity of the cerebral trunk paths extending from the upper cervical marrow and bulb, where the proprioceptive and vestibular transmission of the rotation of the head originates, to the mesencephalus at the level of the third nerve. Thus, complete and conjugated movements induced by oculocephal maneuvers demonstrate the integrity of a large segment of the brain stem and help in eliminating the possibility of a lesion in the brain stem as a cause of the comet.
Incomplete ocular abduction indicates a lesion in the ipsilateral mesencephalus (third nerve) or a lesion in the transmission pathway that mediates the reflex movements of the eye in the FLM (e.g. internuclear ophthalmoplegia).
A damage to the third nerve is usually associated with a dilated pupil and horizontal eye divergence at rest, while FLM destruction is not related to pupillary function and leaves the eyeball in its primary position. Abduction of the eyeballs is in itself more difficult to obtain than abstraction, and subtle anomalies in the "doll's eye" maneuver must be interpreted carefully.
Caloric stimulation of the vestibular apparatus (oculovestibular response) is useful in the oculocephalic test and acts as a stronger stimulus of reflex movements of the eye, but fundamentally providing the same information. Irrigation of the external auditory canal with cold water causes convection currents in the endolymph of the inner ear labyrinth.
An intact path of the brain stem from the labyrinth to the oculomotor nucleus is indicated, with variable latency, by a deflection of both eyes (lasting 30 to 120 seconds) on the side of irrigation with cold water. Therefore, conjugated bilateral eye movements have the same significance as complete oculocephalic responses.
If the cerebral hemispheres are intact, as happens in a hysterical coma, then a rapid corrective conjugate movement is generated from the tonic deviation. The absence of this rapid, rhythmic phase, similar to the nystagmus, signifies a lesion in the cerebral hemispheres or their suppression.
The conjugated horizontal ocular deviation at rest or incomplete eye movements conjugated with the rotation of the head indicates a bridge injury on the side of the paresis with the lost gaze or damage to the frontal lobe on the opposite side. This phenomenon can be summed up by the following aphorism: "The eyes look towards the hemispheric lesion and away from the lesion of the brain stem".
It is usually possible to remove the ocular deviation with damage to the frontal lobe by oculocephalic testing. Crises can also cause the opposite eye deviation with rhythmic, spastic movements on the lost-looking side. On rare occasions, the eyes may, paradoxically, abandon the part of a deep hemispheric lesion ("eyes that look wrong").
In hydrocephalus with the dilation of the third ventricle, the eyeballs frequently rest below the horizontal meridian. Two types of rhythmic eye movements may occur in stupor or coma. Eye myoclonia is a fast, horizontal nistagmus, usually associated with a similar movement of the palate and due to injury to the central tegmental beam, a longitudinal tract in the brain stem. Opsoclonus is an intermittent, spasmodic, irregular movement with variable direction resulting from cerebellar lesions.
A major trap in the diagnosis of coma can occur when reflex eye movements are suppressed medicinally. Then the eyes move as the head moves, as if they were fixed on the spot, thus falsely suggesting an anatomical injury to the brain stem. Overdoses of phenytoin, tricyclic antidepressants and barbiturates are commonly involved, and occasionally alcohol, phenothiazines, diazepam and neuromuscular blockers such as pancuronium.
The presence of normal pupil size and light reaction will distinguish most drug-induced comets from comets produced by damage to the brain stem. Small pupils (1 - 3 mm) and areactive may occur in the presence of a high serum level of barbiturates or secondary hydrocephalus.
Although corneal reflexes are rarely useful on their own, they may be additional signs of abnormalities in eye movements, as they also depend on the integrity of the pontine paths. Touching the cornea with a cotton swab, a response consisting of a short bilateral closure of the eyelid can be observed.
The corneal response may be lost if the reflex links between the fifth and sixth cranial nerve inside the bridge are affected. The normal efferent response is bilateral, with the closure of both eyelids. CNS depressant drugs decrease or eliminate corneal responses soon after paralyzing reflex eye movements but before the pupil becomes areactive in light.
Tomorrow... we discuss the respiratory patterns associated with these signs of the disease.
Have
a good week!
Dorin,
Merticaru