Title: Disorders of Somatic Sensation
1Disorders of Somatic Sensation
- Refer to Chapter 6 of
- Clinical Neurology Textbook
2Disorders of Somatic Sensation
- Review of Anatomy, History, the Sensory
Examination - Reading assignment
- Read pages 200-203
3Disorders 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
4Disorders 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
5Disorders 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
6Disorders 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
7Disorders 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
8Disorders 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
9Disorders 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
10Disorders 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
11Disorders 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)
-
12Disorders 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
13Disorders 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
14Disorders 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
15Disorders 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
16Disorders of Somatic Sensation
- Polyneuropathies
- Diabetes Mellitus
- A metabolic and nutritional neuropathy
- Affects
- CNS
- PNS Cranial Nerves
17Disorders 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
18Disorders 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
19Disorders 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)
20Disorders 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
21Disorders 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
22Disorders 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
23Disorders of Somatic Sensation
- Mononeuropathies
- Radial Nerve Compression
- Causes
- Compression of the radial nerve in the axilla
- Clinical Features
- Motor primarily
- Sensory occasionally
24Disorders of Somatic Sensation
- Mononeuropathies
- Thoracic Outlet Syndrome
- Causes
- Cervical Rib
- Scalene Compression
- Costoclavicular Syndrome
- Clinical Features
- C8/T1 dermatome
- Pain
- Paresthesia
- Resembles CTS
25Disorders 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
26Disorders 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