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Disorders of Somatic Sensation

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... for a longer period of time than normal. Disorders of Somatic Sensation ... Obese patients. Tight belt. Excessive angulation of femur. Clinical Features ... – PowerPoint PPT presentation

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Title: Disorders of Somatic Sensation


1
Disorders of Somatic Sensation
  • Refer to Chapter 6 of
  • Clinical Neurology Textbook

2
Disorders of Somatic Sensation
  • Review of Anatomy, History, the Sensory
    Examination
  • Reading assignment
  • Read pages 200-203

3
Disorders of Somatic Sensation
  • Sensory Changes
  • Peripheral Nerve Lesions
  • Mononeuropathy
  • Lesion of a single nerve usually d/t entrapment
  • Sensory loss in minimal
  • Polyneuropathy
  • Stocking-and-Glove Sensory loss
  • Symmetric
  • Distal gt Proximal
  • Nerve Root
  • Modality loss is dermatomal
  • Possible myotomal weakness

4
Disorders of Somatic Sensation
  • Sensory Changes
  • Cord Lesions (Figs 6-5, 6-6, 6-7)
  • Central
  • Causes syringomyelia, cord tumors, trauma
  • Bilateral asymmetrical loss of pain temp
  • Anterolateral
  • Contralateral loss of pain temp
  • Anterior
  • Weakness paralysis

5
Disorders of Somatic Sensation
  • Sensory Changes
  • Cord Lesions (Figs 6-5, 6-6, 6-7)
  • Post Column
  • Loss of viration, proprioception, 2-pt
    discrimination
  • Cord Hemisection
  • AKA Brown-Sequards Syndrome
  • Loss of spinothalamic tracts, Post Columns,
    Pyramidal tracts

6
Disorders of Somatic Sensation
  • Sensory Changes
  • Brainstem Lesion
  • General
  • Dorsolateral MO Pons
  • Crossed Sensory Deficit Loss of spinothalmic
    tract modalities contralateral limbs trunk and
    ipsilateral face
  • Above the Spinal Trigeminal Nucleus
  • Loss of spinothalamic tract modalities
    contralateral side of the body
  • Medial Lemniscus
  • Contralateral loss of posterior columns

7
Disorders of Somatic Sensation
  • Sensory Changes
  • Thalamic Lesion
  • Loss or impairment of all modalities of sensation
    on the half of the body contralateral to the
    lesion
  • Any form of cutaneous stimuli leads to a painful
    or unpleasant sensation
  • May outlast the stimulus for a longer period of
    time than normal

8
Disorders of Somatic Sensation
  • Sensory Changes
  • Sensory Cortical Lesion
  • All Modalities are affected
  • Deep gt Superficial
  • Contralateral/Unilateral loss of modalities
  • Limbs gt Face Trunk
  • Superifical Lesions
  • Localized affects distal gt proximal
  • Recovery
  • 2-pt usually permanently affected

9
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • AKA Guillain-Barre Syndrome
  • Types
  • Demyelinating Form
  • Axonal Form
  • AMSAN acute motor-sensory axonal neuropathy
  • AMAN acute motor axonal neuropathy

10
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • Pathophysiology
  • Autoimmune Disorder All Forms
  • Demyelinating Form predilection for NR Distal
    PN
  • Hallmark inflammatory lesions
    well-circumscribed areas containing lymphocytes
    macrophages
  • Demyelination
  • Axonal Damage - some

11
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • Pathophysiology
  • Axonal Form
  • NR affected gt PN
  • Wallerian Degeneration degeneration occurs from
    site of the lesion distally (away from cell body)

12
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • Epidemiology
  • Rare 1-2 per 100,000
  • Age any, but higher incidence in the elderly
    population
  • Demyelinating form accounts for 90 of all cases
    in North America, Europe, Australia
  • Antecedent Events (triggers)
  • Occur 1-3 weeks prior
  • URI
  • Vaccines rabbiies esp
  • Viral infections HIV esp
  • Epstein-Barr virus
  • Cytomegalic Virus
  • Bacterial Infections
  • Surgery

13
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • Clinical Features
  • Cardinal Features
  • Paresthesias involves the toes and fingers
    symmetrically initially
  • Weakness not a presenting feature
  • Hypo or Areflexia one of the earliest S/S

14
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • Clinical Features
  • Other Features
  • Poorly localized deep pain
  • Sensory changes seen infrequently, but posterior
    columns most affected
  • Progression
  • Progressive Phase 3-4 wks
  • Plateau Phase 2-4 wks before recovery begins

15
Disorders of Somatic Sensation
  • Polyneuropathies
  • Acute Idiopathic Demyelinating Polyradiculoneuropa
    thy
  • Diagnosis (Table 6-3)
  • Required for Diagnosis
  • Progressive muscle weakness
  • Loss of DTRs
  • Clinical Studies
  • CSF Inc protein w/ normal cell count
  • NAD in 1st week
  • EMG marked dec of motor sensory conduction

16
Disorders of Somatic Sensation
  • Polyneuropathies
  • Diabetes Mellitus
  • A metabolic and nutritional neuropathy
  • Affects
  • CNS
  • PNS Cranial Nerves

17
Disorders of Somatic Sensation
  • Polyneuropathies
  • Diabetes Mellitus
  • Neurological Complications of the CNS
  • Glycemic Extremes
  • Hypoglycemia adrenergic neurolglycopenic
    symptoms are experienced
  • Hyperglycemia - Type I or II, 3 Ps
    (poly-dipsia, phagia, uria)
  • Stroke ? incedence severity
  • Encephalopathy

18
Disorders of Somatic Sensation
  • Polyneuropathies
  • Diabetes Mellitus
  • Neurological Complications of the CNS
  • Atheroma
  • Degeneration or thickening of arteries
  • Arteriolar Capillary Microangiopathy
  • Pseudotabes Diabteica d/t infarction of the
    spinal cord
  • Affects the dorsal root ganglia degeneration of
    post columns

19
Disorders of Somatic Sensation
  • Polyneuropathies
  • Diabetes Mellitus
  • Neurological Complications of the PNS CN
  • Peripheral nerve involvement is common
  • MC is a mixed polyneuropathy presentation (70)
  • Primary sensory polyneuropathy (30)

20
Disorders of Somatic Sensation
  • Polyneuropathies
  • Diabetes Mellitus
  • Neurological Complications of the PNS CN
  • Three Common Manifestations
  • Polyneuropathy Sensory or Mixed, Dx by ? DTRs
    vibratory sensation loss in the legs
  • Mononeuropathy Multiplex Neuropathy in separate
    parts of the body, characterized by pain
    weakness
  • Mononeuropathy Simplex pain is the MC feature
  • Diabetic Amyotrophy
  • Muscular atrophy

21
Disorders of Somatic Sensation
  • Mononeuropathies (Appendix C)
  • Median Nerve Compression
  • AKA Carpal Tunnel Syndrome
  • Causes
  • Pregnancy, Trauma (RSS), Degenerative Arthritis,
    Tenosynovitis
  • Clinical Features
  • Early pain paresthesia in median nerve
    distribution, pain _at_ night
  • Late weakness atrophy with impaired cutaneous
    sensation

22
Disorders of Somatic Sensation
  • Mononeuropathies
  • Ulnar Nerve Dysfunction
  • Causes
  • External Pressure
  • Cubital Tunnel Syndrome
  • Cubitus Valgus Deformity
  • Clinical Features
  • Paresthesia, hypesthesia, nocturnal pain in the
    little finger and ulnar border of the hand
  • Elbow pain
  • Sensory loss Muscle weakness ulnar aspect of
    hand
  • Pain exacerbated by elbow flexion

23
Disorders of Somatic Sensation
  • Mononeuropathies
  • Radial Nerve Compression
  • Causes
  • Compression of the radial nerve in the axilla
  • Clinical Features
  • Motor primarily
  • Sensory occasionally

24
Disorders of Somatic Sensation
  • Mononeuropathies
  • Thoracic Outlet Syndrome
  • Causes
  • Cervical Rib
  • Scalene Compression
  • Costoclavicular Syndrome
  • Clinical Features
  • C8/T1 dermatome
  • Pain
  • Paresthesia
  • Resembles CTS

25
Disorders of Somatic Sensation
  • Mononeuropathies
  • Peroneal Nerve Lesions
  • Causes
  • Secondary to trauma or pressure over thee fibula
    head
  • Clinical Features
  • Weakness or paralysis
  • Toe Extension
  • Foot eversion
  • Impaired Sensation
  • Dorsum of the foot
  • Distal, ant aspect of the leg

26
Disorders of Somatic Sensation
  • Mononeuropathies
  • Lateral Femoral Cutaneous Nerve Dysfunction
  • AKA Meralgia Paresthetica
  • Causes
  • Entrapment as it passes through the inguinal
    ligament
  • Pregnancy
  • Obese patients
  • Tight belt
  • Excessive angulation of femur
  • Clinical Features
  • A pure sensory entrapment
  • Numbness, painful burning itching in the
    lateral thigh
  • Hypesthesia to touch pinprick
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