Focal neurologic deficits
Background Also known as focal neurologic signs [ 1]
Refer to objective abnormalities of a specific region of the body detected on the neurologic examination Focal Neurologic Signs Organized by Region Brain Frontal Lobe
Damage to the frontal lobe can lead to the following signs:
Sensory /motor deficit of the contralateral lower extremityLanguage disturbances
Profound behavioral changes
Indifference, apathy
Disinhibition (labile and irritable)
Impaired judgement, decreased social graces
Akinesia (lack of spontaneous movements)
Impairment of memory
Parietal Lobe
Damage to the parietal lobe can lead to the following signs:
Agnosia
Anosognosia – Unawareness of a deficit
Unilateral spatial neglect (hemineglect)
Dyslexia, dysgraphia, dyscalculia
Impairment of tactile sensation Temporal Lobe
Damage to the temporal lobe can lead to the following signs:
Upper homonymous quadrantanopsia
Cortical deafness
Wernicke’s aphasia (word deafness, auditory verbal agnosia)
Hallucinations Complex partial seizures
Kluver-Bucy syndrome (Bilateral disease. Compulsion to attend all visual stimuli, hyperorality, hypersexuality, blunted emotional reactivity) Occipital Lobe
Damage to the temporal lobe can lead to the following signs:
Contralateral homonymous hemianopia
Cortical blindness (bilateral lesions)
Visual hallucinations
Prosopagnosia
Alexia without agraphia
Loss of topographic memory and visual orientation Limbic System
Damage to the limbic system can lead to the following signs:
Retrograde amnesia (long-term memory loss)
Anterograde amnesia (inability to form new memories)
Apathy
Loss of olfactory functions
Cerebellar
Damage to the cerebellum can lead to the following signs:
Ataxia of voluntary movementsIntention tremor
Dysarthria Postural abnormalities
Hypotonia
Incoordination
Nystagmus , gaze paresis Brainstem
Damage to the brainstem can lead to the following signs:
Crossed deficits – motor or sensory involvement of the face on one side of the body and the arm and leg on the other side
Cranial nerve palsies (see below) Tongue deviation from unilateral hypoglossal nerve injury (CN XII). CN I (Olfactory)
Anosmia + perceived change in taste of food
Deficit caused by shearing of the nerve ending passing through the cribriform plate usually by closed head trauma CN II (Optic)
Monocular and binocular visual field defects
Monocular: Giant cell arteritis , anterior ischemic optic neuropathy, glaucoma , optic neuritis , trauma , increased ICP , emboli/arteritis/stenosis leading to retinal ischemia, ophthalmic artery or vein occlusion
Binocular - Hemianopsia due to bilateral optic nerve disease. CN III (Oculomotor) –See Third Nerve Palsy CN IV (Trochlear) - See Trochlear nerve palsy CN VI (Abducens) - See Abducens nerve palsy Internuclear ophthalmoplegia - Lesion in medial longitudinal fasciculus, cannot adduct in horizontal lateral gaze, but normal convergence. Caused by multiple sclerosis or stroke CN V (Trigeminal)
Jaw weakness and spasm. Jaw closure may be weak and/or asymmetric. +/- Trismus if irritative lesion to motor root.
See trigeminal neuralgia CN VII (Facial)
CN VIII (Vestibular)
CN IX (Glossopharyngeal)
CN X (Vagus)
Dysfunction may be characterized by: hoarseness (unilateral vocal cord paralysis), dyspnea and inspiratory stridor (bilateral). Dysarthria, dysphagia. CN XI (Accessory)
Dysfunction may be characterized by: Sternocleidomastoid and trapezius weakness leads to weak head rotation and shoulder shrug CN XII (Hypoglossal)
Dysfunction may be characterized by: tongue deviation and wasting Upper extremity
Ulnar
Cause of Injury: Elbow injury.
Sensory changes in the 5th and medial half of 4th digits, weak wrist flexors, “claw hand” Radial
Median, distal
Cause of Injury: Wrist dislocation, laceration, Carpal Tunnel Syndrome
Weak flexion of radial half of digits and thumb, loss of abduction and opposition of thumb. Ape hand deformity, benediction sign. Loss of sensation of lateral three and one-half digits and nail beds Median, proximal
Musculocutaneous
Cause of Injury: Anterior shoulder dislocation , entrapment due to hypertrophy
Elbow flexion and supination weakness, radial forearm sensory deficits Axillary
Suprascapular
Cause of Injury: Paralabral cyst, bone/soft tissue tumor, Scapular fracture , traction injury, Parsonage-Turner syndrome
Weak arm abduction to 90 degrees, weak shoulder flexion to 30 degrees, weak internal rotation Lower extremity
Femoral
Cause of Injury: Pubic rami fracture, pelvic fractures
Weak knee extension, anterior knee sensory deficits Obturator
Posterior tibial
Cause of Injury: Knee dislocation
Weak toe flexion, plantar foot sensory deficit Superficial peroneal
Cause of Injury: Fibular neck fracture, knee dislocation
Weak ankle eversion, lateral dorsal foot sensory deficits Deep peroneal
Cause of Injury: Fibular neck fracture, compartment syndrome
Sensory deficit at dorsal 1st web space, weak ankle and toe dorsiflexion Sciatic
Cause of Injury: Posterior hip dislocation
Lower leg weakness, foot drop, leg sensory deficits Superior gluteal
Inferior gluteal
Cause of Injury: Acetabular pelvic fracture , s/p hip replacement
Abnormal gait, gluteus maximus weakness resulting in gluteus maximus lurch Evaluation Sensory Homonculus - courtesy AnatomyZone.com Spinal cord tracts Dermatomes and cutaneous nerves - anterior Dermatomes and cutaneous nerves - posterior Cutaneous innervation of the upper limb Lower limb peripheral innervation Management Treat underlying condition Disposition See Also References
↑ Smith EE, et al. Cerebral Amyloid Angiopathy-Related Transient Focal Neurologic Episodes. Neurology. 2021 Aug 3;97(5):231-238. PMID 34016709
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