Lesions of the Spinal Cord | Anatomy2Medicine
spinal cord lesions

Lesions of the Spinal Cord

Lesions of the Spinal Cord

 

  • Lower Motor Neuron Lesions
  • result from damage to motor neurons of the ventral horns or motor neurons of the cranial nerve nuclei.

 

      • Neurologic deficits resulting from LMN lesions

 

  • Flaccid paralysis
  • Muscle atrophy (amyotrophy)
  • Hypotonia
  • Areflexia

 

          • loss of muscle stretch reflexes (MSRs) (knee and ankle jerks)
          • loss of superficial reflexes (abdominal and cremasteric reflexes).
        • Fasciculations (visible muscle twitches)
        • Fibrillations (seen only on electromyogram)
      • Diseases of LMNs

 

  • Poliomyelitis

 

        • Progressive infantile muscular atrophy (Werdnig-Hoffmann disease)
        • Kugelberg-Welander disease (juvenile hereditary LMN disease)
          • affects the large girdle muscles first and then the distal muscles.

 

  • Upper Motor Neuron Lesions
  • result from damage to cortical neurons that give rise to corticospinal and corticobulbar tracts.

 

      • called pyramidal tract lesions.
        • When rostral to the pyramidal decussation of the caudal medulla, they result in deficits below the lesion, on the contralateral side.
        • When caudal to the pyramidal decussation, they result in deficits below the lesion, on the ipsilateral side.

 

  • Lateral corticospinal tract lesion
  • results in the following ipsilateral motor deficits found below the lesion:

 

          • Spastic hemiparesis with muscle weakness
          • Hyperreflexia (exaggerated muscle stretch reflexes)

 

  • Loss of superficial (abdominal and cremasteric) reflexes
  • Clasp-knife spasticity

 

            • When a joint is moved briskly, resistance occurs initially and then fades (like the opening of a pocketknife blade)

 

  • Clonus

 

            • consists of rhythmic contractions of muscles in response to sudden, passive movements (wrist, patellar, or ankle clonus).

 

  • Babinski sign

 

            • consists of plantar reflex response that is extensor (dorsiflexion of big toe).

 

  • Ventral corticospinal tract leision

 

        • results in mild contralateral motor deficit.
        • Ventral corticospinal tract fibers decussate at spinal levels in the ventral white commissure.
      • Hereditary spastic paraplegia or diplegia
        • is caused by bilateral degeneration of the corticospinal tracts.
        • results in gradual development of spastic weakness of the legs with increased difficulty in walking.

 

  • Sensory Pathway Lesions

 

      • Dorsal column syndrome

 

  • includes the fasciculi gracilis (T6–S5) and cuneatus (C2–T6) and the dorsal roots.

 

        • is seen in
          • subacute combined degeneration (vitamin B12 neuropathy).
          • neurosyphilis as tabes dorsalis
          • nonsyphilitic sensory neuropathies.
        • results in the following ipsilateral sensory deficits found below the lesion:

 

  • Loss of tactile discrimination

 

        • Loss of position (joint) and vibratory sensation
        • Stereoanesthesia (astereognosis)
        • Sensory (dorsal column) dystaxia
        • Paresthesias and pain (dorsal root irritation)
        • Hyporeflexia or areflexia (dorsal root deafferentation)
        • Urinary incontinence, constipation, and impotence (dorsal root deafferentation)
        • Romberg sign (sensory dystaxia) (standing patient is more unsteady with eyes closed)
    • Lateral spinothalamic tract lesion
      • results in contralateral loss of pain and temperature sensation
      • loss is seen one segment below the level of the lesion.
    • Ventral spinothalamic tract lesion
      • results in contralateral loss of light (crude) touch sensation
      • loss is seen three or four segments below the level of the lesion.
    • Dorsal spinocerebellar tract lesion
      • results in ipsilateral leg dystaxia
      • patient has difficulty performing the heel-to-shin test.
    • Ventral spinocerebellar tract lesion
      • results in contralateral leg dystaxia
      • patient has difficulty performing the heel-to-shin test.

 

 

  • Peripheral Nervous System Lesions

 

            • may be sensory, motor, or combined.

 

  • affect spinal roots, dorsal root ganglia, and peripheral nerves.

 

            • Herpes zoster (shingles)

 

  • consists of an acute inflammatory reaction in the dorsal root or cranial nerve ganglia.
  • is usually limited to the territory of one dermatome

 

              • the most common sites are T5 to T10.
              • causes irritation of dorsal root ganglion cell
            • Acute idiopathic polyneuritis (Guillain-Barré syndrome)
              • is also called postinfectious polyneuritis.
              • affects primarily motor fibers
              • causes segmental demyelination and wallerian degeneration.
              • produces LMN symptoms (muscle weakness, flaccid paralysis, and areflexia).
              • results in symmetric paralysis that begins in the lower extremities and ascends to involve the trunk and upper extremities
              • the facial nerve frequently is involved bilaterally.

 

  • elevates cerebrospinal fluid (CSF) protein; however, the CSF cell count remains normal (albuminocytologic dissociation).
  • Combined Upper and Lower Motor Neuron Lesions

 

            • muscle weakness and wasting without sensory deficits.
            • Prototypic disease—amyotrophic lateral sclerosis (AML)
              • is also called Lou Gehrig disease, motor neuron disease, or motor system disease.
              • usually occurs in persons 50 to 70 years of age.
              • involves both LMNs and UMNs; either component may dominate the clinical picture.
              • LMN component

 

  • progressive (spinal) muscular atrophy

 

                • progressive bulbar palsy
              • UMN component.

 

  • pseudobulbar palsy

 

                • primary lateral sclerosis

 

  • Combined Motor and Sensory Lesions

 

            • Spinal cord hemisection (Brown-Séquard syndrome)
              • Dorsal column transection
                • results in ipsilateral loss of tactile discrimination, form perception, and position and vibration sensation below the lesion.

 

  • Lateral spinothalamic tract transection

 

                • results in contralateral loss of pain and temperature sensation,

 

  • starting one segment below the lesion.
  • Ventral spinothalamic tract transection

 

                • results in contralateral loss of crude touch sensation
                • starts three or four segments below the lesion.

 

  • Dorsal spinocerebellar tract transection

 

                • results in ipsilateral leg dystaxia.

 

  • Ventral spinocerebellar tract transection

 

                • results in contralateral leg dystaxia.
              • Hypothalamospinal tract transection rostral to T2
                • results in Horner syndrome.

 

  • Lateral corticospinal tract transection

 

                • results in ipsilateral spastic paresis below the UMN lesion with the Babinski sign.

 

  • Ventral corticospinal tract transection

 

                • results in minor contralateral muscle weakness below the lesion.

 

  • Ventral horn destruction

 

                • results in ipsilateral flaccid paralysis of somatic muscles (LMN lesion).

 

  • Dorsal horn destruction
  • results in ipsilateral dermatomic anesthesia and areflexia.

 

            • Complete transection of the spinal cord
              • Exitus lethalis between C1 and C3
              • Quadriplegia between C4 and C5
              • Paraplegia below T1
              • Spastic paralysis of all voluntary movements below the lesion
              • Complete anesthesia below the lesion
              • Urinary and fecal incontinence, although reflex emptying may occur
              • Anhidrosis and loss of vasomotor tone

 

  • Paralysis of volitional and automatic breathing if the transection is above C5 (the phrenic nucleus is found at C3–C5)

 

            • Ventral (anterior) spinal artery occlusion
              • causes infarction of the ventral two-thirds of the spinal cord.
              • usually spares the dorsal columns and dorsal horns.
              • results in paralysis of voluntary and automatic respiration in cervical segments
              • it also results in bilateral Horner syndrome.

 

  • results in loss of voluntary bladder and bowel control, with preservation of reflex emptying

 

              • results in anhidrosis and loss of vasomotor tone.

 

  • Ventral horn destruction

 

                • results in complete flaccid paralysis and areflexia at the level of the lesion.

 

  • Corticospinal tract transection

 

                • results in a spastic paresis below the lesion.

 

  • Spinothalamic tract transection

 

                • results in loss of pain and temperature sensations
                • starting one segment below the lesion.

 

  • Dorsal spinocerebellar tract and ventral spinocerebellar tract transection

 

                • results in cerebellar incoordination, which is masked by LMN and UMN paralysis.
            • Conus medullaris and epiconus syndromes

 

  • neurologic deficits and signs that are most always bilateral.
  • Conus medullaris syndrome

 

                • involves segments S3 to Co.

 

  • is usually caused by small intramedullary tumor metastases or hemorrhagic infarcts.

 

                • results in destruction of the sacral parasympathetic nucleus, which causes paralytic bladder, fecal incontinence, and impotence.
                • causes perianogenital sensory loss in dermatomes S3 to Co (saddle anesthesia).

 

  • shows an absence of motor deficits in the lower limbs.
  • Epiconus syndrome

 

                • involves segments L4 to S2.

 

  • results in reflex functioning of the bladder and rectum but loss of voluntary control.
  • is characterized by considerable motor disability (external rotation and extension of the thigh are most affected).

 

                • affects the ventral horns and long tracts.
                • is associated with absent Achilles tendon reflex.
            • Cauda equina syndrome
              • classically involves spinal roots L3 to Co.

 

  • results in signs that frequently predominate on one side.

 

              • may result from intervertebral disk herniation.
              • commonly results in severe spontaneous radicular pain.
            • Filum terminale (tethered cord) syndrome
              • results from a thickened, shortened filum terminale that adheres to the sacrum
              • causes traction on the conus medullaris.
              • results in sphincter dysfunction, gait disorders, and deformities of the feet.
            • Subacute combined degeneration (vitamin B12 neuropathy)
              • associated with pernicious anemia.

 

  • consists of demyelination of dorsal columns, resulting in loss of vibration and position sensation.
  • consists of demyelination of spinocerebellar tracts, resulting in arm and leg dystaxia.
  • consists of demyelination of corticospinal tracts resulting in spastic paresis (UMN signs).

 

            • Friedreich hereditary ataxia
              • is the most common hereditary ataxia with autosomal recessive inheritance.
              • dorsal column, spinocerebellar, and corticospinal tract involve ment.
              • cerebellar involvement (Purkinje cells and dentate nucleus) is frequent with progressive ataxia.
              • commonly leads to cardiomyopathy, pes cavus, and kyphoscoliosis.
            • Syringomyelia
              • is a central cavitation of the cervical spinal cord of unknown etiology.
              • results in destruction of the ventral white commissure

 

  • interruption of decussating spinothalamic fibers, causing bilateral loss of pain and temperature sensation.
  • can result in extension of the syrinx into the ventral horn, causing an LMN lesion with muscle wasting and hyporeflexia.
  • Atrophy of lumbricals and interosseous muscles of the hand is a common finding.

 

              • can result in extension of the syrinx into the lateral funiculus, affecting the lateral corticospinal tract and resulting in spastic paresis (a UMN lesion).
              • can result in caudal extension of the syrinx into the lateral horn at T1 or lateral extension into the lateral funiculus (interruption of descending autonomic pathways), resulting in Horner syndrome.
            • Multiple sclerosis
              • is the most common form of demyelinating disease.
              • has asymmetric lesions
              • may affect all tracts of the spinal cord white matter

 

  • Spinal cord lesions occur most frequently in the cervical segments.

 

            • Charcot-Marie-Tooth disease (hereditary motor–sensory neuropathy type I)
              • is also called peroneal muscular atrophy.
              • is the most common inherited neuropathy.
              • affects the posterior columns, resulting in a loss of conscious proprioception.

 

  • affects the anterior horn motor neurons, resulting in muscle weakness (atrophy)
  • Intervertebral Disk Herniation

 

              • consists of prolapse or herniation of the nucleus pulposus into the vertebral canal
              • occurs through the defective annulus fibrosus.

 

  • The nucleus pulposus impinges on spinal roots, resulting in root pain (radiculopathy) or muscle weakness.

 

              • may compress the spinal cord with a large central protrusion
              • is recognized as the major cause of severe and chronic low back and leg pain.
              • appears in 90% of cases at the L4–L5 or L5–S1 interspaces
              • usually a single nerve root is compressed,
              • several may be involved at the L5–S1 interspace (cauda equina).

 

  • appears in 10% of cases in the cervical region, usually at the C5–C6 or C6–C7 interspaces.
  • is characterized by spinal root symptoms, which include paresthesias, pain, sensory loss, hyporeflexia, and muscle weakness.

 

          • Cervical spondylosis with myelopathy
            • is the most commonly observed myelopathy.
            • consists of spinal cord or spinal cord root compression by calcified disk material extruded into the spinal vertebral canal.
            • presents as painful stiff neck, arm pain and weakness, and spastic leg weakness with dystaxia
            • sensory disorders are frequent.