Sensation Kinds and types of sensory disturbance Syndromes of lesion

Sensation is an ability of an organism to accept stimuli from external and internal environment

Classification of sensation І. Classification, which is based on the place of originating of stimuli:  Exteroceptive  Interoceptive  Proprioceptive

Classification of sensation ІІ. Classification, which is based on biological principle of originating of sensation:  Protopatical (vital, nociceptive, thalamic). This ancient sensation is typical for the primitive nervous system of our ancestors  Epicritical sensation is connected with cortex and it is based on the differentiation of stimuli according to their modality, intensity, localization etc

Classification of sensation In clinical practice usually we use classification, which is based on the kind of stimuli:  Superficial  Deep  Complicated

Superficial sensation - light touch  pain  temperature  Trihoesthesia – is a sensation of touch of hair  Hydroesthesia – is a sensation of humidity  Sensation of electrical current  Feeling of tickling

 Superficial pain – is a feeling of pain, which can be tested with a corsage pin or pinwheel (acutely or bluntly, pricks or does not prick)

 Light touch (tactile) sensation – is feeling of touch, which may be examined by touch of cotton, end of hammer, paintbrush

 Temperature sensation – is feeling of cold or hot, which may be tested by application of glass tubes filled with iced (10 C) and hot (43 C) water to the skin

Deep sensation This includes joint and vibratory sense and pain from the deep-lying somatic structures, namely, muscle, ligaments, fascia, bone, and so on.  Feeling of mass (baroesthesia) – is the ability to distinguish different weights  Feeling of pressure - is the ability to distinguish pressure from touch

 Joint sense (bathyesthesia) - is the ability to distinguish position and passive movements in joints

The joint sense The loss of joint sense, which is called bathyanesthesia, results in disturbance of muscular coordination and is known as sensitive ataxia. 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:  static  dynamic

Static ataxia in legs can 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 can be examined 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-to-nose test, and in legs - heel-to-knee test.

Vibration sense (pallesthesia) –   is the ability to distinguish different vibration

 Kinesthesia - is a sensation of movement of dermal fold

Complicated sensation  Localization sense - is the ability to point an exact place of the stimuli  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  Baragnosis – is the impaired ability to distinguish different weights

 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.

Complicated sensation  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

Anatomy of Superficial sensation tracts This tract carry out pain, temperature and part of tactile sense and has three neurons.  The 1 neuron is situated in unipolar cell bodies in ganglion spinalis of dorsal root of the spinal cord and homologous ganglia of the Cranial nerves.  The 2 neuron - is 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 of the spinal cord in the lateral spinothalamic tracts.  The 3 neuron – are nuclei of thalamus. The axons form Thalamocortical tract

SensoryHomunculusSensoryHomunculus

Anatomy of Deep sensation explorers  The first neuron – is in the unipolar cell bodies in the dorsal root ganglia of the spinal cord and homologous ganglia of the cranial nerves - Medial Holl’s tract fibers pass from Th4 and below (carries out deep sense from lower extremities and bottom of trunk) - Lateral Burdach’s pathway - from Th4 and higher (carries out deep sense from upper extremities and top of a trunk)  The second neuron - is in Holl’s and Burdach’s nuclei of medulla oblongata. The axons of the second neuron create Bulbothalamic tract. The fibers of this path are crossed on olives level of medulla oblongata, on the Pons of brain stem they join of Spinothalamic tract lateral and create a medial closed loop (lemniscus medialis) The axons of the 2-d neurons carry all sorts of sensation from opposite side of the body  The third neuron - is in thalamus, from which cells thalamocortical tract starts

Sensory innervation of the face  The first neuron of face, nasal sinuses, oral cavities and nose sensory conductors are situated in Trigeminal (Gasser’s ganglion). Those for larynx mucouse membrane, pharynx, radix of tongue - in ganglions of Vague and Glossopharyngeal nerves (ganglion superior and inferior). Those for 2/3 front of tongue - in a geniculate ganglion (ganglion geniculi) of facial nerve  The second neurons are situated in the sensitive nuclei of the adequate cranial nerves in brain stem. 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

TrigeminothalamicTract A. trigeminal ganglion B. trigeminal sensory nucleus nucleus C. thalamus (VPM) D. cerebral cortex (S I) 1. spinal tract of trigeminal nerve trigeminal nerve 2. ventral trigeminothalamic tract trigeminothalamic tract 3. dorsal trigeminothalamic tract trigeminothalamic tract 4. corona radiata V. trigeminal nerve

Objective sorts of sensory disorders  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  Hypoesthesia - lowering of sensation.  Hyperesthesia – increasing of sensation

Objective sorts of sensory disorders  Dysesthesia - distortion of sensitivity, when instead of one stimulus the patient feels absolutely other. For example, warm touch one feels as cold  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  Synesthesia - sensation of stimuli not only in a place of its plotting, but also in the other place

Objective sorts of sensory disorders  Polyesthesia - means sensation of one stimulus as several ones  Alloheyria - sensation of stimuli in symmetrical sites on an opposite body part  Alloesthesia - sensation of stimuli in the other place  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:  Paresthesia is a creeping sensation, cold, burning sensation, fever, numbness, itch, the pricking etc. Frequently paresthesia is the first sign of nervous system lesion  Pain The pain sensations can arise at stimuli by the pathological process of sensitive analyzers at any level (from receptors up to cortex)

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 innervation not 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

Sorts of pain 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

Sorts of pain 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

Straight leg raising test

Types of sensory disturbances Peripheral type Peripheral type   Mononeuritic (or neural)   Polyneuritic   Plexal Segmental (sectional) type  Segmental - radicular  Segmental - dissociated Conductive type  Spinal  Cerebral

The peripheral type  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

The peripheral type

 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

The peripheral type  Plexal pattern - occurs at lesion of peripheral plexus and appears by sensation disturbance in innervative zone of a plexus and pains

The segmental (sectional) type disturbance of sensation is observed at lesion of sensitive fibbers at segment level of spinal cord disturbance of sensation is observed at lesion of sensitive fibbers at segment level of spinal cord  Segmental - radicular pattern  Segmental – dissociated pattern

Sectional body building

Lesion of dorsal root: - pain -loss of all sorts of sensation in its zone innervation according to the segmental type (transversal strip on a trunk and longitudinal strip on extremities) -areflexion

Lesion of spinal nerve: - pain -loss of all sorts of sensation in its zone innervation according to the segmental type (transversal strip on a trunk and longitudinal strip on extremities) -peripheral paresis of segmental muscules

The segmental (sectional) type  Segmental - dissociated pattern is observed at lesion of dorsal horns of spinal cord and front grey soldering.  loss or lowering pain and thermoanesthesia and saving tactile and joint sense in given segment.  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

Conductive type The lesion of sensory explorers in: The lesion of sensory explorers in:  Spinothalamic tract  Holl’s and Burdach’s pathways  Bulbothalamic tract  Medial closed loop  Thalamocortical tract

Conductive type  Spinal  Cerebral

Spinal pattern  Descending  Ascending, depending on extra- or intramedular lesion  Monotype  Hemitype

Conductive type Cerebral subtype  Brain stem  The thalamic  Capsular  Cortical

Multiple peripheral nerves lesion  loss all kinds of sensation in distal parts of extremities - «gloves» and «socks»  pains  paresthesias  distal peripheral paresis  distal autonomic disorders

Dorsal root lesion loss all kinds of sensation by segmental type in innervative segmentloss all kinds of sensation by segmental type in innervative segment painpain  areflexion

Types of sensory disturbances

Types of sensory disorders