Neurological examination of Sensation, Reflexes and Motor functions Baspakova Kadisha 577 GM

SENSATION There are three types of primary (basic) sensation: 1.Exteroceptive sensation 2.Proprioceptive sensation 3.Interoceptive sensation Cortical (combined) sensation

Clinical evaluation of extroceptive sensation Patients may report a lack of sensation over part of the body, or may be unaware of the deficit. With various lesions of the sensory system, but particularly with peripheral nerve disorders, they may complain of PARESTHESIA or DYSESTHESIA. Paresthesia is an abnormal, spontaneous sensation, not provoked by stimuli, often describe as tingling, or pins and needles. Dysthesia is an uncomfortable, at times painful, hypersensitivity to non- noxious stimuli and my be elicited when examining the patient.

The sensory examination consists of applying typical test stimuli to the patients skin, while he or she, with eyes closed, tries to identify the type of stimulus correctly, and whether the stimulus is consistently decreased or absent over certain area. Light touch Pinprikck sensation Tempreture sensation Vibration sensation

Clinical evaluation of proprioceptive sensation Proprioceprtive sensation is also called position sense or joint sense. Testing is preformed by raising or lowering the patients finger or toe subtly a few degrees at one joint. The patient, with eyes closed, identifies the movement as up or down. If the patient detects only large excursions of the finger or toe, but consistently misses smaller movements, position sense is decreased there. If even large joint movements are not perceived, position sense is there absent. In that case, position sense may be preserved more proximally, which can be noted by testing more proximal joints such as the ankle or wrist.

Clinical evaluation of combined sensation These sensory modalities involve object recognition (gnosis) as well as perception of objects or more complex stimuli. A lesion in the parietal sensory cortex or its connecting pathways produces a cortical sensor deficit contralateral body, while primary sensations may be relatively intact. Stereognosis refers to the tactile recognition of familiar or common objects, with patients eyes closed. A deficit – ASTEREOGNOSIS. GAPHASTHESIA involves the identification of numbers traced on the palm with the patients eyes closed. A deficit - AGRAPHESTHESIA or GRAPHANESTHESIA.

DOUBLE SIMULTANEOUS STIMULATION refers to the ability to perceive two tactile stimuli applied simultaneously to the same bilateral parts of the body, such as both hands or both feet, again with the patients eyes closed. When bilateral tactile stimuli are given, the consistent failure to detect a stimulus on one side is due to a contralateral parietal cortical lesion, and is described as EXTINCTION ON DOUBLE SIMULTANEOUS STIMULATION.

TWO POINT DISCRIMINATION (fine touch) is the ability to detect the simultaneous application of two sharp points separated by a minimal distance on the skin. A deficit here consists of perceiving the two points as one point, or failing to feel it all.

Anatomical localization of sensory deficits In disorders of peripheral nerves, initial involvement of the larger, more myelinated sensory fibers causes impairment of position sense and vibration, while initial involvement of the smaller, less myelinated or unmyelinated sensory fibers produces early impairment of temperature and pain (or pin) sensation. Eventually, if the peripheral neuropathy becomes extensive and severe, all fibers and all sensory modalities will be impaired.

If lesions exist in specific sensory pathways in the spinal cord or brainstem, certain sensory modalities may be lost while others are preserved. Lesions of the posterior or dorsal columns lead to deficits in position sense, vibration, and two-point discrimination. Although generally regarded as a primary is basic exteroceptive sensation, vibration sense is conveyed mainly via the posterior (dorsal) columns, and thus is clinically associated with the proprioceptive sensation of position sense. Isolated deficits of two-point discrimination have been associated with contralateral sensory cortex lesions.

Lesions of the spinothalamic tract create deficit in pain sensation and temperature. More than one spinal cord pathway conveys the sensation of light touch, so absence of light touch sensation occurs only in extensive lesion of the spinal cord or its dorsal roots (or in severe peripheral neuropathy or thalamic lesions).

Lesions of the posterior or dorsal columns lead to deficits in position sense, vibration, and two-point discrimination. Although generally regarded as a primary is basic exteroceptive sensation, vibration sense is conveyed mainly via the posterior (dorsal) columns, and thus is clinically associated with the proprioceptive sensation of position sense. Isolated deficits of two-point discrimination have been associated with contralateral sensory cortex lesions.

It is not only the type of sensory loss that is important for localization is a lesion, but also where the deficit maps out on the patient's body. In the case of a mononeuropathy, sensation is decreased or lost in the territory of one peripheral nerve. If there is a polyneuropathy, sensation is decreased or lost in several peripheral nerves, creating a "stocking and glove" distal pattern of deficit.

Dermatomal deficits are sensory impairments in the territory of one or more dermatomes from one or multiple root lesions. In the case of a single dermatomal lesion, a sensory deficit may not be clearly detected on examination because of the normal overlap of dermatomal sensory territories. The patient's own reported localization of sensory abnormality, parenthesia or dysesthesia is often more helpful in tat situation. In spinal cord lesions (myelopathies), dissociation of sensation is characteristic (loss of one modality of sensation with preservation of another), although this may occur in brain stem lesions.

Intermedullary spinal cord lesions occur within the spinal cord parenchyma, causing a suspended is vestlike sensory loss and sacral (dermatome) sparing of sensory deficit. Extramedullary spinal cord lesions compress the spinal cord from outside, creating an initial sensory loss in sacral segments, progressing up "to a level" because of limitation of the spinothalamic tract. A hemisensory (hemibody) deficit of basic sensations on the right or left side of the body including the face is caused by a contralateral thalamic lesion, or involvement of sensory pathways to the contralateral parietal lobe. Isolated or predominant deficits involving cortical or combined sensations typically occur on one side of the body, and are usually due to a lesion in the contralateral parietal sensory cortex.

Interceptive sensation Interceptive sensation typically involves visceral pain by an inflamed internal organ, as in appendicitis, or a sense of fullness or pressure, as from a distended bowel or bladder. It is poorly localized at times, in comparison to other modalities, except for the scenario of referred pain. Referred pain is perceived along a dermatome having sensory afferents from the same dorsal root level as the diseased internal organ. A heart attack may be heralded by pain along the inside of the left arm and forearm (C8, T1 dermatomes) while an infection below the right diaphragm may cause pain at the right shoulder (C3,4,5 dermatomes).

REFLEXES A reflex is a quick, automatic, replicable motor response or muscle contraction provoked by a stimulus. In neurological disease, normal physiological reflexes may be increased, decreased or lost, and abnormal pathological reflexes may appear especially with upper motor neuron lesions. Clinically important reflexes include muscle stretch reflexes (deep) and superficial reflexes.

Muscle stretch reflexes Muscle stretch reflexes (MSRs) are elicited by the hammer tap of a selected tendon, which causes a brief or single contraction of its muscle. The commonly tested MSRs: -afferent reflex -efferent reflex

Jendrassik maneuver The Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of fingers into a hook-like form and interlocks those sets of fingers together. The tendon below the patient's knee is then hit with a reflex hammer to elicit the patellar reflex. The elicited response is compared with the reflex result of the same action when the maneuver is not in use. Often a larger reflex response will be observed when the patient is occupied with the maneuver, as the maneuver may prevent the patient from consciously inhibiting or influencing his or her response to the hammer.

Abnormalities of muscle stretch reflexes Disorders disrupting the afferent or efferent reflex arcs may cause MSRs to be decreased (hypoteflexia) or absent (areflexia), which often occurs in polyneuropathy or radiculopathy. However, healthy older adults may have absent ankle reflexes merely due to aging. Abnormally increased MSRs (hyperreflexia) occur with upper motor neuron lesions, where the inhibitory effect on the local reflex circuit from descending supraspinal tracts is lessened. Asymmetrical hyperreflexia on one side of the body strongly suggests an upper motor neuron (corticospinal tract) lesion.

Superficial reflexes Most superficial reflexes are cutaneous reflexes, provoked by tactile stimuli to a localized area of skin or mucous membrane. An exception is the pupillary light reflex, where stimulation involves shining light into the pupil oh the eye. The cranial nerve-mediated superficial reflexes are characteristically consensual, with a bilateral response to a unilateral stimulus: touching one cornea produces a bilateral blink for the corneal reflex. The afferent and efferent reflex arcs of different cranial nerves. -abdominal reflex cremasteric reflex

Pathological (abnormal) reflexes The most important and reliable pathological reflex is Babinski sign, which indicates an upper motor neuron (corticospinal tract) lesion in the adult. -Hoffmans sign -Tromners sign

Miscellaneous clinical signs Meningial signs are noted when the meninges are inflamed and irritated from infection or subarachnoid hemorrhage. Nuchal rigidity is the stiffness felt by the examiner when the patients head is passively flexed in the anterior direction. Kernings sign Brudzinskis sign Lasegues sign

Motor functions The pronator drift suggests a subtle proximal upper limb weakness from a corticospinal tract lesion. The examiner would see slow pronation and downward drift of an outstretched, supinated arm. Subtle weakness of the hand may be manifest more as impaired finger dexterity rather than gross weakness of certain muscles. The strenght of individual muscles cam be graded on a scale from 0 to 5.

Patterns of weakness Focal weakness may occur in the territory of on peripheral nerve, or segmentally, such as the thigh or hand, where the weak muscles are innervated by more than one nerve or spinal root. The weakness of one root may be partial (monoparesis) or complete (moniplegia). Myelopathic weakness from a bilateral spinal cord lesion, may involve botj lower limbs, from a lesion at the thoracic level. This lower limb weakness may be partial (paraparesis) or complete (paraplegia). All four limbs may be weak from the cervical spinal cord lesion, whether partial (qyadriparesis) or complete (quadraplegia).

A hemiparetic (partial) or hemiplegic (complete) weakness of the upper and lower limbs on one side is typically due to an upper motor neuron lesion in the ipsilateral spinal cord or contralateral brain or brain stem. In a patient with muscle disease, the typical myopathic pattern of weakness involves the proximal limbs, namely at the shoulders and hips. In a patient with a peripherial neuropathy (polyneuropathy), the neuropathic pattern of weakness is distal, involving the feet, and later the hands.

Muscle tone Hypotonicity- decreased Hypertonicity – increased 1. Spasticity -the increased ton in spasticity is unequal between agonist and antogonist. 2. Rigidity-type, where the increased tone feels equal between agonist and antogonist muscles.

References 1.Neurologic Examination of Sensation Reflexes and Motor Function (Dr.Merchut); p.1-12

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