Assessment and localisation

Neurological examination and localisation

Overview and approach

Neurological localisation identifies whether a lesion is cortical, brainstem, spinal, peripheral nerve, neuromuscular junction or muscle.

  • Localise first (where is the lesion?), then think about cause (what is it?), guided by time course and distribution.
  • An inflammatory or neurodegenerative process can be spinal; if spinal, expect upper motor neuron signs below the lesion. A T10 spinal lesion is usually described as causing bilateral lower limb weakness; a slipped (herniated) disc is on the differential. A cord lesion at a thoracic level gives UMN signs in the legs, whereas root/cauda equina lesions give LMN signs (3)(4).
Assessment and clinical features

Assess time course, cognition, cranial nerves, tone, power, reflexes, sensation, coordination and gait.

  • Examine cranial nerves, tone, power, reflexes, sensation (including saddle/perianal sensation when indicated), coordination and gait; test anal tone and bladder function if cauda equina or conus lesions are possible (5).
Differentials and investigations

UMN signs suggest central pathways; LMN signs suggest motor unit pathology, but acute central lesions may initially be flaccid.

  • UMN signs: spasticity, hyperreflexia, clonus, extensor plantar response and usually little atrophy. LMN signs: hypotonia, hyporeflexia or areflexia, fasciculations and focal atrophy (1)(2).
  • The conus medullaris is spinal cord, so lesions can give mixed UMN and LMN signs; the cauda equina is nerve root (peripheral), so lesions give LMN signs (3)(4).
Management and follow-up

Choose tests by localisation and urgency; communicate the syndrome and likely lesion site before listing diagnoses.

  • Cauda equina syndrome: asymmetric weakness, hyporeflexia, saddle anaesthesia and bladder/bowel dysfunction; conus lesions are more symmetric, with the patellar reflex preserved but Achilles reflex lost, and possible spasticity (5). See the Myelopathy page.
Red flags and clinical pearls

Acute weakness, sensory level, sphincter symptoms or bulbar/respiratory compromise needs urgent escalation. A T10 cord lesion is not simply a lower-motor-neurone disorder.

References
  1. StatPearls: Neuroanatomy, Lower Motor Neuron Lesion
  2. Loyola Lumen: Spinal Cord Disorders
  3. Merck Manual Professional: Overview of Spinal Cord Disorders
  4. Epomedicine: Conus medullaris vs cauda equina syndrome
  5. StatPearls: Cauda Equina and Conus Medullaris Syndromes

Last updated from Sen’s notes on 9 October 2026.