Grade of reflexes
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Based on the textbook sources and my knowledge, here is a complete, well-organized answer on reflex grading.
Grading of Reflexes
Reflexes (specifically deep tendon reflexes / DTRs) are graded on the standard 0 to 4+ scale, which is the most widely used system in clinical neurology.
The Standard 0-4+ Scale (NINDS Scale)
| Grade | Description | Clinical Meaning |
|---|---|---|
| 0 | Absent - no response | Areflexia; suggests LMN lesion, peripheral neuropathy, or severe myopathy |
| 1+ | Diminished / hypoactive (present only with reinforcement) | Hyporeflexia; LMN lesion, peripheral nerve disease, hypothyroidism |
| 2+ | Normal | Expected physiologic response |
| 3+ | Brisker than average / hyperactive (without clonus) | May be normal in some patients, or early UMN lesion |
| 4+ | Very brisk; associated with clonus | Hyperreflexia with clonus; strongly suggests UMN lesion |
Note: Some texts split Grade 4 into 4+ (sustained clonus) and reserve clonus as a separate finding; others use 4+ to denote clonus itself. The key is always to document symmetry and context.
Commonly Tested Deep Tendon Reflexes and Their Root Values
| Reflex | Nerve Root | How Elicited |
|---|---|---|
| Biceps | C5, C6 | Tap biceps tendon at the antecubital fossa |
| Brachioradialis | C5, C6 | Tap radius ~5 cm above the wrist |
| Triceps | C7, C8 | Tap triceps tendon above the olecranon |
| Patellar (knee jerk) | L2, L3, L4 | Tap patellar tendon below the patella |
| Medial hamstring | L5 | Tap medial hamstring tendon |
| Achilles (ankle jerk) | S1, S2 | Tap Achilles tendon |
Clinical Interpretation
Hyporeflexia (0 to 1+)
- Lower motor neuron (LMN) lesion
- Peripheral neuropathy (e.g., diabetic, Guillain-Barre)
- Cerebellar lesion (ipsilateral)
- Hypothyroidism
- Acute spinal shock (initially decreased even with UMN injury)
- Elderly patients may normally lose the Achilles reflex bilaterally
Hyperreflexia (3+ to 4+)
- Upper motor neuron (UMN) lesion (e.g., stroke, myelopathy, MS)
- Note: acute UMN lesions often present with decreased reflexes initially; hyperreflexia develops over hours to weeks as spasticity sets in
Clonus
- Rhythmic, sustained oscillating contractions triggered by sudden passive stretch (typically tested at the ankle)
- Pathological when sustained (>4-5 beats)
- Indicates significant UMN dysfunction
UMN vs. LMN: Reflex Summary
| Feature | UMN Lesion | LMN Lesion |
|---|---|---|
| Reflexes | Hyperreflexia (eventually) | Hyporeflexia / Areflexia |
| Tone | Spasticity | Flaccidity |
| Atrophy | Minimal (disuse) | Prominent |
| Fasciculations | Absent | Present |
| Plantar reflex | Extensor (Babinski +) | Flexor (normal) |
- Neuroanatomy through Clinical Cases, 3rd Edition (Blumenfeld) - Signs of UMN vs LMN lesions, Table 3.3
- Harrison's Principles of Internal Medicine, 22nd Edition - Neurologic Diagnosis section
- Rheumatology, 2-Volume Set (Elsevier, 2022) - Deep Tendon Reflexes section
Reinforcement Techniques (when reflex seems absent)
If a reflex cannot be elicited, use Jendrassik maneuver (patient interlocks and pulls their fingers apart) before testing lower limb reflexes, or clench teeth/squeeze fist for upper limbs. This increases physiologic excitability via descending facilitation and can bring out a 1+ reflex that would otherwise be missed.
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