Neurosurgery notes/Functional/Spasticity/Surgical spasticity/Plastics

Plastics

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Surgical spasticity
  • Upper limb spasticity and selective peripheral neurotomy (SPN)
    • Upper limb spasticity is characterized by
      • A combination of spastic and flaccid paralysis.
      • There is spasticity of the flexor pronator muscles combined with flaccidity of the opposite extensor supinator muscles.
        • Results in an adducted, internally rotated shoulder, a flexed elbow, a pronated forearm, a flexed and ulnarly deviated wrist, and a clasped hand with a thumb- in- palm deformity.
        • The flexor pronator tonicity increases with passive stretch and is constant, except during sleep or under anaesthesia.
        • The hypertonic muscles cocontract when the antagonists are used affecting the grasp and release ability.
      • MDT management aims to maintain function and range of movement.
          • Non-surgery (use first)
          • Physiotherapy,
          • Splinting,
          • Tone reducing medication,
          • Botulinum toxin
          Surgical options
          • Rebalancing (tendon transfers),
          • Contracture release (myofascial release, musculotendinous lengthening, joint releases),
          • Joint stabilizing procedures,
          • Tone reducing procedures (SPN or selective denervation)
            • SPN is only used in cases where excessive hypertonia is impeding function.
            • Trial procedure
              • Botulinum toxin treatment
                • Mimics the potential effects of SPN on selected nerves and should be used as a preliminary treatment before considering SPN.
              • Local anaesthetic blocks
                • In the outpatient setting can also be used to assess the outcome of potential neurotomy.
            • SPN can be used in isolation or in combination with tendon transfers, releasing and stabilizing procedures.
            • The aim is to reduce excessive hypertonicity without suppressing useful muscular tone or impairing residual motor and sensory functions.
            • Technique
              • Sectioning of both afferent and efferent pathways of the stretch reflex at the level of the neuromuscular junction.
                • Afferent pathway section causes loss proprioception of the muscle
                • Efferent pathway section induces paralysis.
              • Neurotomy should never involve a mixed nerve trunk of sensory and motor fibres as this can cause deafferentation pain.
                • The responsible motor branches are isolated using intraoperative nerve stimulation together with the operating microscope for visualization.
              • Variable portions (50– 80%) of the isolated motor branches are resected and cauterized to prevent regrowth of fibres.
              • The extent of partial section is dependent upon the response to electrical stimulation
            • Outcome
              • Depends upon accurately identifying the hypertonic muscles preoperatively and precisely partially denervating these muscles.
              • Recurrence of spasticity can occur when the amount of sectioning is insufficient, however the operation can be repeated.