What is the likely outcome from a lesion at C5 (cervical spine 5) on the left side in Brown Sequard syndrome, is it left flaccid paralysis or left spastic paralysis?

Brown-Séquard Syndrome at C5 (Left Side): Motor Manifestations

In Brown-Séquard syndrome with a lesion at C5 on the left side, the patient will present with left spastic paralysis (upper motor neuron lesion), not flaccid paralysis.

Neuroanatomical Basis

Brown-Séquard syndrome results from hemisection (damage to one side) of the spinal cord, producing a characteristic pattern of neurological deficits:

• Ipsilateral (same side as the lesion) findings:

  • Spastic paralysis below the level of lesion due to corticospinal tract damage
  • Loss of proprioception and vibration sense due to posterior column damage
  • Segmental lower motor neuron signs at the level of the lesion

• Contralateral (opposite side) findings:

  • Loss of pain and temperature sensation beginning 2-3 segments below the level of injury due to spinothalamic tract damage

Why Spastic Paralysis Occurs

At the C5 level on the left side, the hemisection affects:

1. Corticospinal tract fibers that have already crossed in the medulla (upper motor neurons)

   • These fibers control voluntary movement on the left side of the body
   • Damage results in upper motor neuron signs: spasticity, hyperreflexia, and positive Babinski sign

2. Anterior horn cells at C5 level only

   • This produces a small zone of flaccid paralysis and areflexia limited to the C5 myotome (primarily deltoid muscle)
   • This is the only area where lower motor neuron signs would appear

Clinical Differentiation

• Spastic paralysis (correct answer for this case):

  • Characterized by increased muscle tone
  • Hyperactive deep tendon reflexes
  • Positive Babinski sign
  • Occurs below the level of lesion due to upper motor neuron damage

• Flaccid paralysis (incorrect for this scenario except at C5 level itself):

  • Characterized by decreased muscle tone
  • Hyporeflexia or areflexia
  • Muscle atrophy
  • Would only occur at the exact level of injury (C5 myotome)

Supporting Evidence

Multiple case reports document that Brown-Séquard syndrome typically presents with spastic paralysis below the level of injury 1, 2, 3. The pathophysiology involves interruption of the descending motor pathways that have already crossed in the medulla, resulting in upper motor neuron signs 3.

Prognosis

Brown-Séquard syndrome generally has a favorable prognosis compared to other spinal cord injury patterns. Most patients show substantial neurological recovery with appropriate management including rehabilitation 1, 2. According to case reports, patients with traumatic Brown-Séquard syndrome often achieve good functional recovery with conservative management and intensive physical therapy 4.