Sensation. Signs of sensation disturbances
Sensation and reception
Sensation is an ability of an organism to accept stimuli from external and internal environment. Reception is a set of all afferent systems, which accept stimuli from external and internal environment and carry them out to the center. Reception is wider concept, than sensation. One doesn’t not feel everything he accepts. Sensation is a part of reception, which one feels and can analyze by certain structures of his brain. It means that sensation is closely connected with activity of analyzers.
Analyzers and its structures
Analyzer is a sole functional system that consists of three parts:
1. Receiving apparatus (receptors) – receptor part
2. Sensory explorers – conductive part
3. Part of cortex, which receives information, analyzes and synthesizes it.
The main function of Analyzer is to accept and analyze stimuli. We distinguish the following analyzers: Visual, Acoustical, Sensual, Testate.
Reception apparatus
Receptors are sensitive structures that have ability to accept different changes of external and internal environment and transmit them as impulse.
Receptors are divided into:
1. Exteroreceptors (in skin and external mucose membrane)
2. Proprioreceptors (in muscles, tendons, joints)
3. Interoreceptors (in inner organs, in vessels)
There are also telereceptors in ears and eyes.
1. Exteroreceptors accept superficial sensitiveness (light touch (tactile), pain and temperature sense). They are divided into mechanoreceptors (touch, pressure), thermoreceptors (cold, hot), nociceptors (accept pain).
The tactile sense is perceived by tactile Меrkеl’s bodies on fingers tips.
Меysnеr’s bodies on palms, soles, lips, on the end of the tongue are very sensitive to any touch.
Fater-Pachini’s bodies in deep layers of skin perceive sense of pressure.
Cold receptors are situated in flasks Krause’s.
Thermal receptors are located in Puffin’s bodies.
More fibers react to cold stimuli than to thermal ones.
Pain is accepted by free nervous endings between epidermal cells.
2. Proprioreceptors are situated in deep tissues (muscles, joints, tendons). The muscular receptors are variable. The most important of them are nervous – muscular cords. They react to tension of muscles. They are covered by a connective tissue case and are situated intra- and extrafusally between the fibers of striated muscles.
The Goldie’s and Matson’s bodies accept joint feeling. They are situated between muscles and tendons.
Besides, there are also osmoreceptors, chemoreceptors, baroreceptors and others.
The impulse is transmitted from the receptor apparatus to the cerebrum by means of nerve fibers. The last are axons of unipolar cells of dorsal root ganglia.
There are 3 types of fibers:
1. Type A – thin myelin fibers, which carry out deep and light touch sense; the speed of impulse transmission by these fibers is 40-60 m/s
2. Type B – myelin fibers, which carry out pain and temperature sense; the speed is 10-15 m/s
3. Type C – without myelin fibers, which carry out diffuse pain sense with speed 1-1,5 m/s.
Classification of sensation
Depending on the special interest of the investigator, sensation may be classified in many different ways. The neurologist, in his search for the location and cause of neurological disease, finds it convenient to classify sensation into: superficial and deep.
Each of the main groups includes different modalities which will be discussed separately. There are different classifications of sensation.
І. Classification, which is based on the place of originating of stimuli. According to this classification sensation is divided on:
1. Exteroceptive
2. Interoceptive
3. Proprioceptive
ІІ. Classification, which is based on biological principle of originating of sensation. According to this one sensation is divided into:
1. Protopatical (vital, nociceptive, thalamic). This ancient sensation is typical for the primitive nervous system of our ancestors.
2. Epicritical sensation is connected with cortex and it is based on the differentiation of stimuli according to their modality, intensity, localization etc.
In clinical practice usually we use classification, which is based on the kind of stimuli. According to clinical classification sensation is divided into:
1. Superficial
2. Deep
3. Complicated
Superficial sensation
This term includes the modalities of light touch, pain and temperature.
1. Light touch (tactile) sensation – is feeling of touch, which may be examined by touch of cotton, end of hammer, paintbrush;
2. Superficial pain – is a feeling of pain, which may be tested with a corsage pin or pinwheel (acutely or bluntly, pricks or does not prick);
3. Temperature sensation – is feeling of cold or hot, which may be tested by application of glass tubes filled with iced (
4. Trihoesthesia – is a sensation of touch of hair;
5. Hydroesthesia – is a sensation of humidity;
6. Sensation of electrical current;
7. Feeling of tickling.
Deep sensation
This includes joint and vibratory sense and pain from the deep-lying somatic structures, namely, muscle, ligaments, fascia, bone, and so on.
1. Joint sense – is a sense of position and passive movements
2. Vibration sense
3. Feeling of mass
4. Feeling of pressure
5. Kinesthesia
1. The joint sense (bathyanesthesia) – is a deep sense, which is based on the ability to distinguish position and passive movements in joints. Position sense or proprioception is tested by gently moving a terminal phalanx – in the lower extremities by vertical movements of the toes and in the upper extremities by similar movements of the thumbs and fingers. Examination of this feeling is always started from movements in joints of fingers, then – in a carporadial joint and further – in ulna etc. The loss of joint sense, which is called bathyanesthesia, results in disturbance of muscular coordination and is known as sensitive ataxia.
Sensitive ataxia is divided on:
a) static
b) dynamic
Static ataxia in legs may be investigated by means of Romberg’s test – patient is asked to stand directly with the extended forward arms and feet together. In case of ataxia difficulty of standing and instability occurs. That is magnified while eyes are closed.
Static ataxia in arms may be investigated by follows: we ask patient to extend forward arms and to place fingers separately. In case of ataxia consensually spontaneous (involuntary forced) movements (pseudoathetosis) in fingers of arms occurs.
Dynamic ataxia in arms may be examined by means of finger-nasal test, and in legs – heel-knee test.
2. The vibration sense (pallesthesia) – may be tested by placing the base of the tuning fork over a bony prominence (it can be back of the hand, feet) during vibration and again when the fork is stopped (silent control application). We must control how many seconds the patient feels vibration of a tuning fork (to the moment when he feels only pressure). Normally in arms it is – 15-20 s, in legs – 10-15 s.
4. The sensation of weight (baroesthesia) – is the ability to distinguish different weights, and it may be examined with the help of small weights, which are put in the patient’s palm. Normally the patient distinguishes a difference of weight about 15-
5. The sensation of pressure – is determined by simple pressing of finger or instrument baresthesiometer. The patient should feel pressure of different force and distinguish pressure from touch.
6. Kinesthetic sense is a sensation of movement of dermal fold.
Complicated sensation (Integrative function of parietal cortex)
The role of the cortex in sensory appreciation is discriminative. Destruction of the parietal cortex does not produce anesthesia for any modality of sensation except as a transitory phenomenon. The basic sensation of pain, temperature, vibration, and touch are recognizable as such, but the ability to make fine sensory distinctions is impaired over the contra lateral side of the body – facial sensation being least affected for some reason.
1. Stereognosis (Three-point distinction) is the ability to identify familiar object placed in the palm of the patient by palpation when the eyes are closed. It is complicated kind of sensation, which is based on the reception of separate properties of object (weight, form, surface, and sizes), synthesis and analysis of all these properties in the cerebral cortex and is particularly related to activity in the parietal lobes. For example, to identify by touch (with the closed eye) a pen, hammer etc.
2. Graphism – is the ability to determine figures and numbers traced on the skin with the closed eyes. Graphesthesia – impaired graphism is very sensitive indicator of parietal lobe damage.
3. Localization sense – is the ability to point an exact place of the stimuli.
4. Discrimination sense (two-point discrimination) – tests the ability of the patient to differentiate one stimulus from two. It may be examined by Weber’s circus. After the patient closes his eyes the doctor puts stimuli by circus branches on either one side or both sides of skin of his body. At first pulling branches together, and then enlarging distance between them. He marks thus on what distance the patient feels two simultaneously put stimuli as two, and on what as one. The test leads are most sensitive of fingers, tough. The results of examine estimate under the special table.
5. Baragnosis – is the impaired ability to distinguish different weights.
Anatomy of Superficial sensation pathways
The way which carries out pain, temperature and part of tactile sense has three neurons.
The first neuron is situated in unipolar cell bodies. The last are located in dorsal root ganglia of the spinal cord and homologous ganglia of the cranial nerves (ganglion intervertebral or ganglion spinals). Their dendrites are routed on peripherals within plexuses, peripheral nerves. There they are finished in various sensory skin receptors. The axons of these unipolar cells enter the spinal cord through the dorsal roots in a basis of dorsal horns, where they are finished.
The second neuron – the cells of the second neuron are situated in dorsal horns of the spinal cord. The axons create tractus spinothalamicus. The axons of these neurons cross the midline through the ventral commissura and go to the opposite lateral funiculus and then run in the lateral spinothalamic tracts. These tracts run upwards to the brain stem, where they pass through the oblong brain, the Varoliy’s pons, and peduncles of brain and are finished in nuclei of thalamus.
The features of spinothalamic tracts, which have diagnostic value
1. The decussating in front of white soldering occurs not in a horizontal plane at a level of segment, but obliquely from below upwards during 1-2 segments. Therefore if we have lesion of lateral funiculus, the sensitive disturbance occurs on the opposite side 1-2 segments below than the level of a pathological focus.
2. The caudal contributions to the spinothalamic tract are pushed laterally by the incoming contributions from higher up results in a lamination of the tract, with the fibers from the lowers segments of the spinal cord placed more dorsolaterally on each side. This explains the “sacral” sings and symptoms that result from more or less superficial involvement of the lateral funiculus even at the highest level of the cord. It is the Auerbah-Flatau’s law of eccentrically allocation of longer explorers.
Taking into account this fact it is possible to make the conclusion. In case of extramedular pathological process (for example, the tumors squeezing a lateral fibber of lateral funiculus of spinal cord) disturbances of sensation will accrue from below upwards (at first on foot, then on leg, thigh, and the trunk, further in an arm (hand)), that is the ascending type of sensitive disturbance. In case of intramedular pathologic process (when first lesion of medial fibers is in lateral funiculus of spinal cord) sensitive disturbance will be distributed from above downwards, that is descending type of sensitive disturbance.
The third neuron is located in the nucleus of thalamus. The axons form thalamocortical tract and pass through internal capsule, then within radiate crown, and are ended in post central gyrus and parietal lobes of brain hemisphere, and in upper parts of a gyrus – the sensation from lower extremities, on the average – from upper extremities, in lower – from the face and tongue are ended.
Anatomy of Deep sensation explorers
This pathway has also 3 neurons.
The first neuron The unipolar cell bodies are located in the dorsal root ganglia of the spinal cord and homologous ganglia of the cranial nerves (ganglion intervertebral or ganglion spinals). The dendrites are routed on peripherals within plexuses, peripheral nerves, where they are ended in various sensory receptors in muscles, tendons and joints. The axons of these unipolar cells enter the spinal cord through the dorsal root and run in dorsal funiculus on one side of the spinal cord, where it divides into two paths – medial thin Holl’s pathway and lateral Burdach’s pathway. In Holl’s pathways fibers pass from segment Th4 and below, and in Burdach’s pathway, from segment Th4 and higher. That means the Holl’s path carries out deep sense from lower extremities and bottom of a trunk, and Burdach’s path – from upper extremities and top of a trunk.
This feature has topical and diagnostic value: at extramedular processes (for example, in cervical part of spinal cord) the disturbance of deep sense accrue for the descending type, and, on the contrary, at intramedular processes of spinal cord disturbance of deep sense occurs for the ascending type.
The second neuron is in Holl’s and Burdach’s nuclear of oblong brain. The axons of the second neuron create bulbothalamic tract. The fibers of this path are crossed on olives level of oblong brain, on the pons of brain stem they join fibers of spinothalamic tract lateral and create a medial closed loop. The medial closed loop (lemniscus medialis) consists of fibers of spinothalamic tract and bulbothalamic tract. The axons of the second neurons carry all sorts of sensation from opposite side of the body. The medial closed loop is ended in ventral nucleus of thalamus.
The third neuron – is in thalamus, from which cells thalamocortical tract starts. The axons of this path go through internal capsule, radiation crown and are ended in a postcentral gyrus, partially in the right central gyrus and in parietal lobes of a share. It is necessary to tell, that a part of fibers from the second neurons of deep sense are routed not to a thalamus, but to a cerebellum through lower legs of a cerebellum.
The part of impulses from muscles, tendons, joints, deep tissues run to a cerebellum (to its worm) after spinocerebral paths. For example, in dorsal horns of spinal cord there are cells, which axons borrow (occupy) lateral funiculus and rise to brain stem as spinoreticular, spinoolivar, spinovestibular, spinotectal pathways.
Sensation innervation of the face is carried out as follows
The first neuron of face, nasal sinuses, oral cavities and nose sensory conductors are situated in trigeminal (Gasser’s ganglion). Those for larynx mucose membrane, pharynx, radix of tongue – in ganglions of wandering and glossopharyngeal nerves (ganglion superior and inferior). Those for 2/3 front of tongue – in a geniculate ganglion (ganglion geniculi) of Facial nerve.
The axons of the first neurons as a part of sensitive roots of cranial nerves (V, VІІ, IX, Х a steam) are routed to a brain stem.
nucleus tractus spinalis n. trigemini
nuсleus terminalis
nucleus alae cinerea
The second neurons are situated in the sensitive nuclei of the adequate cranial nerves. The axons of the second neuron make decussate and after that join medial closed loop, in which structure pass to ventral-lateral nuclei of a thalamus.
The third neuron is in thalamus. The axons form thalamocortical tract, pass through internal capsule, a radiate crown and are ended in lower parts of postcentral gyrus.
Symptoms of sensory disturbances (sorts and types of sensory disturbances)
Depending on qualitative and quantitative changes of sensation in clinic we distinguish the following objective sorts of sensory disorders:
1. Anesthesia – complete loss of any sorts of sensation. For example:
Analgesia – loss of pain sense.
Thermoanesthesia – loss of a temperature sense
Bathyanesthesia – loss of deep joint sense
Astereognosia – loss of stereognostic sense
Topanesthesia – loss of localization sense
Pallanesthesia – loss of vibratory sense
2. Hypoesthesia – lowering of sensation.
3. Hyperesthesia – sensitization as result of lowering a threshold of energization in cortex of brain.
4. Dysesthesia – distortion of sensitivity, when instead of one stimulus the patient feels absolutely other. For example, warm touch one feels as cold.
5. Hyperpathia – results from rise of a threshold of energization, when there are strong, unpleasant, badly localized sensations of stimuli. Thus the mild stimuli are not received absolutely. In basis of hyperpathia the disturbance of the analytical function of cortex lays.
6. Synesthesia – sensation of stimuli not only in a place of its plotting, but also in the other place.
7. Polyesthesia – means sensation of one stimulus as several ones.
8. Alloheyria – sensation of stimuli in symmetrical sites on an opposite body part.
9. Alloesthesia – sensation of stimuli in the other place.
10. Dissociation of sense – phenomenon of fallout of some kind of sensitivity while saving others in the area of segment innervation.
Subjective sorts of sensory disturbances:
1. Paresthesia is a creeping sensation, cold, burning sensation, fever, numbness, itch, the pricking etc. Frequently paresthesia is the first sign of nervous system lesion.
2. Pain. The pain sensations can arise at stimuli by the pathological process of sensitive analyzers at any level (from receptors up to cortex). Pain is one of the most common complaints to be brought to the physician attention. The initial goal of the neurologist is to ascertain whether the pain represents disease of the nervous system as contrasted with visceral, ischemic, musculoskeletal, or psychosomatic causative factors. The most common pains of neurological origin, except headache, are those that originate from lesions of the peripheral nerves and the spinal roots. Of less frequency but of no less importance are those kinds of pains that reflect dysfunction of the sensory tracts of the central nervous system or thalamus.
Determine the following sorts of pain:
1. Local pain – is pain, for example, at palpation of the nervous trunk. That is pain, which coincides with the place of lesion.
2. Projectional pain – is a pain in zone of innervatioot only in place of stimuli, but also distally on a course of nerves or roots. To projection belongs the stump neuralgia – pain in absent segments of an extremity after its ablation. Or other pain example: during a trauma of a ulna nerve in the field of a ulna joint the pain gives back in V fingers of a paintbrush.
3. Irradiating pains – are pains, which are distributed from one nerve branch to another, not struck. For example, at neuralgia of the first branch of trigeminal nerve the pain is distributed to zone of innervation of the second or the third branches, in upper or lower jaw, in ears etc.
4. Displayed pains – are pains in zones Zacharyin-Hed’s at diseases of inner organs, when irradiation arises to certain zone on skin through cells of dorsal horns of spinal cord. For example, pain on ulnar territory of the left forearm and paintbrush at angina pectoris.
5. Causalgia (Greek causes – burning sensation, algos – pain). It is intensive thermalgia originating, for example, at traumas. It is pain without stimulation.
6. Reactive pains – are pains that originate at expansion of nerves. The pains can arise at palpation of pain points and at band spread of nervous trunks.
There is a set of pain points, for example, point of an exit of branches of trigeminal nerve, supraclavicular and subclavian point Herb’s for humeral plexus, scapular point Lasarev’s, junta spinal points, pain points at palpation of acanthus vertebra, interposes intervals, point Hara’s at pressing of transversal processes lumbar vertebras, point Raymist’s – point of lumbar-sacral concatenation, pain points Valle’s – on course Sciatic nerve, pain point of Femoral nerve at pressing of middle of pupart sheaf. Signs of a tension the following: Laseque’s sign, Wassermann’s sign, Nery’s sign, Matskevich’s sign and many others. The pain points and tension signs will be shown to you on practical lesson during learning a special neurology.
Types of sensory disturbances
Determine the following types of sensory disturbances:
1. Peripheral
2. Segmental (sectional)
3. Conductive
1. The peripheral type occurs at lesion of dendrites of the first neuron of all sorts of sensation. The peripheral type is divided on:
a) Mononeuritic (or neural) pattern – is observed at lesion of one peripheral nerve and consists of disturbance of all sorts of sensation in innervative zone of this nerve. There is a pain in the field of nerve, sometimes hyperpathia, hyperalgesia, causalgia, tension signs of nerve, pain at palpation.
b) Polyneuritic pattern – is observed at multiple, frequently symmetric lesion of all peripheral nerves. Appears by sensory disturbance in distal parts of extremities as “socks” on legs and “gloves” on arms. The “stocking-glove” pattern of sensory loss is typical for peripheral neuropathy. But sometimes cerebral or spinal lesion may cause distal sensory loss, usually of a single extremity in the case of cerebral disease, and often in association with hyperreflexia and the Babinski sign in cases of either cerebral or spinal lesions.
c) Plexal pattern – occurs at lesion of dorsal root ganglia and appears by sensation disturbance in innervative zone of a plexus. In this case there are pains, tension signs of nerves going from a plexus, movement disturbance – peripheral paresis of muscles group, which innervated from this plexus.
d) “Saddle-area” pattern of sensory loss. This area is the “tail-end” of the body and is innervated by the sacral segments of the spinal cord and the sacral roots. A lesion producing saddle-area sensory loss will be found in the upper lumbar spinal level if it is due to a lesion of the cord (conus medullaris). The lesion will be at the middle of lower lumbar or upper sacral spinal level if it involved the cauda equina. Defective control of the urinary bladder and anal sphincter are regularly associated with this type of sensory deficit.
It is necessary to point, that at lesion of a peripheral nerve, many peripheral nerves and plexuses, in which near the sensitive fibers pass also movements pathway, simultaneously with sensitive disturbance there are the signs of flaccid paralysis or paresis.
2. The segmental (sectional) type disturbance of sensation is observed at lesion of sensitive fibers at segment level of spinal cord, and, means, at lesion of dorsal root ganglion, dorsal roots, dorsal horns of spinal cord, front white soldering.
Subtypes of a sectional type:
a) Segmental – radicular
b) Segmental – dissociated
a) Segmental – radicular pattern occurs at a lesion of dorsal root or simultaneous lesion of root and dorsal root sensitive ganglion. At lesion of dorsal root there is a loss of all sorts of sensation in its zone innervation according to the segmental type. The sensitive disturbance is appeared as transversal strip on a trunk and longitudinal strip on extremities (in human being there are 36 sensitive segments (31 spinal segments are on trunk and extremities and 5 segments at the expense of trigeminal nerve on the face).
(To show a segmental structure of the man body – table)
This type of disturbance of sensation arises at radicupathyes, at extramedular tumors. At lesion of dorsal root ganglion occurs herpes exanthema in a zone innervation of the struck segment (at a ganglionitis or ganglioneuritis) as bubbles (so-called herpes zoster), sharp pains and anesthesia in a segment.
b) Segmental – dissociated pattern. It is observed at lesion of dorsal horns of spinal cord and front grey soldering. Thus the disturbance of sensation appear as loss or lowering pain and thermoanesthesia and saving tactile and joint sense in given segment. Such disturbance are called dissociated and result from that in dorsal horns and front grey soldering pass explorers of superficial sensation, and from the explorers of deep feeling that do not go to a dorsal horn of spinal cord (recollect anatomy).
The dissociated type of disturbance of sensitivity more often arises at a myelosyringosis, when the sensitive disturbance are observed in certain dermatomes as “jacket” or “half jacket” at lesion of dorsal horns of spinal cord in thoracic segments, or “trousers” – at lesion of dorsal horns of spinal cord in lumbar segments.
It is necessary to remember, that lesion of dorsal roots or dorsal horaturally reduces or kills away reflexes, which are makes by the same dorsal root or dorsal horn.
3. Conductive type.
The lesion of sensory explorers in spinothalamic tract, Holl’s and Burdach’s pathways,
bulbothalamic tract, medial closed loop and thalamocortical tract in limits spinal cord or brain cause conductive type of sensory loss. This type is divided on:
1. Spinal
2. Cerebral
The sensory disturbance from the defined level of a lesion and downwards is typical for both subtypes.
1. Spinal pattern can be:
a) Complete transversal (is observed at a lesion that involves a diameter of a spinal cord, at which all sorts of sensation below that level of a lesion drop out, pain and temperature sense drop out on 1-2 segments below than level of a lesion, and deep – from the same level. Usually, the deficits are in the lower trunk and legs, are bilateral and almost symmetric.
b) Half transversal or Brown-Sequard pattern – arises at a lesion of a lateral half diameter of a spinal cord, thus the deep feeling drops out on the side of a lesion, and pain and temperature sense- on the opposite side, since a level on 1-2 segments is lower.
c) Descending
d) Ascending, depending on extra- or intramedular lesion
e) Monotype
f) Hemitype
2. Cerebral pattern is divided on:
a) Brain stem pattern (alternating). At lesion of sensory fibbers in brain stem there is fallout of sensation on the face according to the segmental type on the side of lesion both fallout pain and thermoanaesthesia on trunk and extremities on opposite sides. Lesions in the pons and below in medulla and cord may result in dissociated sensory loss on one or both sides of the body because of different levels of crossing of the sensory pathways. A lesion of the lateral medulla (lateral medullar syndrome, called Wallenberg’s syndrome) will cause loss of pain sensation on the same side of the face and the opposite side of the body. In this situation, touch is preserved in areas where there is loss of pain perception.
b) The thalamic pattern (at a lesion of thalamus) is observed:
1. Hemihypoesthesia of all sorts of sensation on opposite side from the pathological focus.
2. Hyperpathia – the disturbance of deep feeling prevail
3. There are thalamic pains (burning, intolerable)
4. Hemiataxia – as result of lowering deep joint feeling.
c) Capsular pattern – in case of a lesion of sensory fibers in back leg of internal capsule arises hemi anesthesia of all sorts of sensation on opposite sides and hemiataxia owing to fallout of deep feeling.
d) Cortical pattern – arises at a lesion of a postcentral gyrus and upper parietal gyrus. Thus the sensation drops out on monotype in an arm either in a leg, or on the face depending on localization of a lesion in a postcentral gyrus.
The cerebral or thalamic disorders, when the lesions are above the pons, cause sensory disturbances that involve one entire side of the body. This pattern is also found in cases of hysteria, but then the line of demarcation usually is precisely in the midline, whereas in organic deficits demarcation is short of the midline. At stimuli of a postcentral gyrus cortical subtype paresthesia appears on the opposite side to the focus, on the face, in arm or in leg. At lesion of parietal share combined and deep sorts of sensation suffer (develops astereognosis or fallout of joint feeling). The syndrome of disturbance of joint feeling can be shown as afferent paresis. This syndrome for the first time was described by Fester in 1936. Appears – disturbance of movement functions owing to disturbance of joint sense. Such movement disturbances are characterized by disturbance of coordination of movements, awkwardness, and deceleration of movements. The syndrome of afferent paresis can be tag of a lesion of parietal share of a brain.
Syndromes of lesion of sensory explorers at different levels
1. The lesion of peripheral nerve – appears by fallout of all sorts of sensation in the field of a nerve, pains, paresthesia.
The pain and paresthesia produced by lesions of the peripheral dermal nerves are usually limited to the region supplied by the affected nerve or nerves. There is often burning or prickling in quality, sometimes described as “sharp”. The location of the pain complained of may be compared with the area of skin supplied by the dermal nerves, although the clinical description by the patient may not conform exactly to the graphic region depicted.
In lesion of nerves composed of both somatic motor and sensory fibers, corroboration in diagnosis may be afforded by the detection of weakness, wasting, decrease in the muscle stretch reflex, and electromyography findings of the denervation in the muscles supplied by the affected nerve peripheral to the site of the lesion.
Signs of autonomic fiber involvement may include alteration in sweating, skin hue, texture, temperature, and distribution of hair.
In peripheral neuropathy, the subjective disturbances are the same as in dermal neuropathy but are confined to the distal portion of the extremities, usually most prominent in the lower limbs. In mononeuritis multiplex, the lesions are disseminated; the several nerves are involved at random.
2. The lesion of plexus – appears by fallout of all sorts of sensation on one extremity, pains, paresthesia, and vegetative disturbances. Diseases of the brachial or lumbar-sacral plexus are usually associated with pain which may be maximal in the proximal limb with variable extension diffusely or to a portion of the involved extremity.
3. Lesion of sensory (dorsal) nerve root – loss of all sorts of sensation for the sectional type in zone of innervation of the certain segment, and also pain, lowering of reflexes.
Spinal lesions should be given diagnostic characteristics as follows:
a) the first of these characteristics is localization of the pain in the dermatomes supplied by the affected nerve root. The pain, although often widely distributed throughout the dermatome, occasionally is limited to a small area within it. It is important to remember this point, since it frequently accounts for failure in diagnosis. The charts depicting dermatomes serve an important function in determining whether the pain under consideration is of radicular origin. Although dermatome in distribution, nerve roots pain in the limbs seldom extends beyond the wrist or ankle. Furthermore, in most instances, pain in the spinal column which is temporally associated with pain in a limb, with paresthesia, or with both, is present.
As a rule, the pain extends to regions that approximate the dermatome distribution of the nerve root supplying the irritated viscous or deep somatic structures.
The most reliable features of root pain are aggravation by the chin-chest maneuver, intensification after several hours in a horizontal position, and amelioration soon after assuming an upright position.
b) root pain is frequently produced or, when present, is aggravated by coughing, sneezing, straining, as in defecation, or any other measures that suddenly increase intra-thoracic and intra-abdominal pressure.
c) root pain may be awaken in the patient at night after several hours of sleep and may be relieved approximately 15 to 30 minutes after the upright position is assumed.
d) root pain often results from, or is intensified by, other maneuvers that stretch the involved roots.
Lower lumbar and sacral roots may be stretched from the periphery by the straight-leg raising test (Laseque’s sign) or by bending forward, as in an attempt to touch the floor without bending the knees.
Cervical roots may be stretched by downward or downward and outward, displacement of the shoulder girdle.
The chin-test maneuver of passively flexing the neck so that the chin rests on the chest induces ascension of the spinal cord within the spinals canal. Thus, the nerve roots, particularly those of the lower thoracic, lumbar, and sacral segments, are placed under tension, with consequent production of pain from any one of them which may be diseased.
e) root pain may be aggravated by those spinal motions that narrow the intervertebral foramen thought which the diseased nerve root passed. In cervical root disease, simultaneous extension and lateral flexion of the neck to the affected side alone or after a blow to the vertex of the head (Spurling’s sign) may result in sudden aggravation of the neck and dermatome arm pain, paresthesia, or both.
In the lumbar region, lateral flexion of the spinal column toward the affected side further narrows the neutral foramen and may result not only in aggravation of the spinal pain but also in dermatome limb pain and paresthesia.
4. Lesion of a sensory (dorsal) root and ganglion – same manifestations + herpes zoster.
5. The lesion of a sensory (dorsal) horn of a spinal cord cause the same manifestations, as well as at lesions of sensory (dorsal) root, dissociated disorders of sensation only are observed.
6. The lesion of front grey soldering cause sectional type – dissociated disorders of sensation symmetric on both sides as “butterfly”.
7. The lesion of dorsal funiculus of spinal cord – deep feeling drops out on one side according to the conductive type
8. The lesions of lateral funiculus of spinal cord – pain and temperature sense drops out on the opposite side according to the conductive type.
9. The lesion of half of diameter of a spinal cord, Brown-Sequard sign – on the side of the focus deep sense drops out according to the conductive type from level of lesion. Paresis of an extremity, the zone of an anesthesia at level of lesion and radicular pain, is observed on opposite side – drops out pain and temperature sense 2 segments lower than level of focus.
10. Lesion of diameter of a spinal cord – there is anesthesia of all sorts of sensation according to the conductive type is lower than a level of focus: deep sense from a level of focus, superficial sense – 2-3 segments lower. Central paralysis. Defective control of the urinary bladder and anal sphincter according to the central type. Trophic disorders.
11. Lesion of a medial closed loop – hemianestesia, sensitive hemiataxia.
12. Lesion of thalamus – hemianestesia, sensitive hemiataxia, hemianopsia, hemialgia.
Since the thalamus is concerned with sensory impulses from the opposite side of the body, the pain resulting from lesions within it is confined to the opposite side of the body. In large lesions the entire opposite half of the body, including the head, may exhibit hyperpathia discomfort. In less extensive lesions the pain may be limited to large contiguous portions of the body, such as the whole lower extremity and lower part of the trunk or the side of the head, upper extremity, and chest.
Characteristically, thalamic pains appear as the patient is recovering from a thalamic infarct. These pains are persistent and are greatly aggravated by emotional stress and fatigue. They are usually described as burning, drawing, and feeling of pulling, swelling, and tenseness, above all they have a peculiar, highly distressing quality.
13. Lesions of sensory pathways in internal capsule – hemianesthesia, hemianopsia, hemiplegia
14. Lesions of postcentral gyrus – monoanesthesia on the opposite side.
15. Stimulations of postcentral gyrus – sensory “Jackson”.
