S
Scanning Speech - Un-natural Speech (Dysarthria) characterized by Staccato-like Articulation, that sounds clipped because of unintentional pauses between syllables and skips some of their sounds. #28
Sclerosis - Hardening of tissue. In MS, sclerosis is the body's replacement of lost Myelin, around CNS Axons with scar tissue. Early Lesions are usually ReMyelinated and functions restored. However, if Astrocytes make Sclerosis (Gliosis), Myelin can NOT be repaired and the damage is permanent. #28
Secondary/Progressive MS - A clinical course of MS which initially is Relapsing/Remitting and then becomes progressive at a variable rate, possibly with an occasional relapse and minor remission. #28
- MS that begins with a pattern of clear-cut relapses and recovery, but it becomes steadily progressive over time with continued worsening between occasional acute attacks. #29
(Also See: Types of MS)
Segment, Spinal Cord - One defined portion of the Spinal Cord, which are: Eight Cervical Segments (Neck & Upper Extremities); Twelve Thoracic Segments (Chest); Five Lumbar Segments (Lower Trunk & Lower Extremities); and Five Sacral Segments (Buttocks, Bowel, Bladder and Sexual Function). #01
Sensory - Receptor mechanisms monitoring changes in both external and internal environment and convey this data to the CNS.
- Such as: Pain, Smell, Taste, Temperature, Vision, Hearing, Touch, and ProprioCeption (Acceleration and Position In Space). This awareness enables the coordination and quick implementation of survival reactions. (View: Image)
Sensory Cortex - The network of Neurons located along the Cerebral Parietal Lobe's surface.
Sensory Input - Stimuli that the Nervous System receives from the external or internal environment: includes Pressure, Taste, Odor, Sound, Light, and Blood pH.
(View: Image)
Sensory Neurons - The Cell-Bodies of Axons carrying signals from receptors that transmit information about the environment, to processing centers in the Brain and Spinal Cord. Spinal Cord Neurons processing messages from peripheral receptors are sometimes called Afferent Neurons, InterNeurons, or Lower Motor Neurons.
Sensory Pathways (Afferent) - Axons carrying information from organs and tissues to Cortical control centers (Thalamus, Parietal Lobe). #28 (View: Upper, Lower)
Sequela - A condition following or caused by a previous disease; an after effect of illness. #09
Sign, Neurologic - An objective physical problem or abnormality identified by a doctor during the Neurological Examination. Neurological signs may differ significantly from the symptoms reported by the patient, because they are identifiable only with specific tests and may cause no noticeable symptoms. #28
- Any evidence of malfunction perceived by a physican. #01
(Also See: Babinski's Sign And Romberg's Sign)
SomatoSensory Evoked Potentials - A painless test which records nerve message transmission times within the Brain, in response to repeated electrical shocks, applied to a Peripheral Nerve. Slower response times are typically present in early MS, especially the Nerves of the legs and feet.
- Normally, the Brain's reaction to such stimuli is almost instantaneous. DeMyelination or a Lesion in the Nerve Pathway causes a delay, so reception time will be significantly slower than normal. #25
(Also See: Evoked Potentials)
Spasticity - CNS damage caused by Multiple Sclerosis, prevents Nerve messages from reaching the Brain's higher control area (Cerebellum); thus it is unable to inhibit the reflex orders (Muscle Contracting) initiated in the Spinal Cord.
- Muscle groups normally work together, when one is flexed, its opposing muscle is relaxed. MS disrupts this communication causing muscles to needlessly stay tight or contracted. This increased muscle tone is called Spasticity. Increased Muscle Tone - Tightness or Stiff Muscles, usually around a Joint. #04
- Increased resistance to movement. It refers to the stiffness that can occur in a Limb, usually in the Leg. Spasticity often accompanies Weakness, but it is possible to have Spasticity without Weakness and to have Weakness without Spasticity. #25
- Spasticity tends to occur most frequently in a specific group of muscles that are responsible for maintaining our upright posture, referred to as Anti-Gravity or Postural Muscles. These include the Calf (Gastrocnemius), Thigh (Quadriceps), Buttock (Gluteus Maximus), Groin (Adductor) and occasionally the Back (Erector Spinae) Muscles. #06
Spinal Cord - Is the communication link between the Brain and the Peripheral Nervous System (PNS) inferior to the head; it integrates incoming Nerve impulses and produces responses through Reflex mechanisms. (View: Function, Structure)
- The cord extends from the Foramen Magnum to the level of the 2nd Lumbar Vertebra. It is composed of Cervical, Thoracic, Lumbar, and Sacral Segments, which are named according to the area of the Vertebra Column from which their Nerves enter and exit.
- Thirty-one pairs of Spinal Nerves exit the Spinal Cord and pass out of the vertebral column through the InterVertebra Foramia. Nerves to the extremities pass thru:
The Cervical Enlargement - in the inferior Cervical region corresponds to the location at which Nerves that supply the upper limbs enter or exit the cord
The LumboSacral Enlargement - in the inferior Thoracic and superior Lumbar regions is the site at which the Nerves that supply the lower limbs enter or exit
- In cross section, the Spinal Cord consists of a central Gray portion and a peripherial White portion. The White Matter consists of Nerve Tracts, and the Gray Matter consists of Nerve Cell Bodies and Dendrites. An Anterior median Fissue and a Posterior median Sulcus are deep clefts partially separating the two halves of the Cord. #11
Suppressor T-Lymphocytes - White Blood Cells (Lymphocytes) which inhibit or stop certain Immune activity, and which may be in short supply during a MS exacerbation. #28
Synapse - The specialized junction between Neurons, there is no anatomical continuity between them. Instead, the gap is crossed by, NeuroTransmitters.
- They diffuse across the Synapse completing the connection, from the end branch of a PreSynaptic Axon, to the Dendrite, Cell Body, or Axon of a PostSynaptic Neuron. #20, #25
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