hyperreflexia

DEFINITION of hyperreflexia

Hyperreflexia is the exaggeration of normal deep tendon reflexes (DTRs) or other reflex arcs resulting from loss of inhibitory control by upper motor neurons (UMN). In the somatic nervous system, it presents as brisk or clonus-producing tendon reflexes (e.g., patellar, Achilles), often accompanied by spasticity, the Babinski sign, and clonus — all hallmarks of an upper motor neuron lesion (cerebral cortex, corticospinal tract, or spinal cord above the reflex arc). In the autonomic nervous system, autonomic dysreflexia (autonomic hyperreflexia) is a potentially life-threatening syndrome occurring in patients with spinal cord injury at or above T6, characterized by massive, uncontrolled sympathetic discharge triggered by a noxious stimulus below the level of injury — most commonly bladder distension, bowel impaction, or pressure ulcers — producing hypertensive crisis, bradycardia, diaphoresis, flushing, and headache. In urology, detrusor hyperreflexia (now termed neurogenic detrusor overactivity) refers to uninhibited detrusor contractions caused by suprasacral neurological lesions. Hyperreflexia as an isolated finding is a symptom code; when it reflects a specific neurological or urological syndrome, the underlying condition drives code selection.

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ETYMOLOGY of hyperreflexia

greek latin

Component	Origin	Meaning
hyper-	Greek ὑπέρ (hypér)	“Over,” “above,” “excessive,” “beyond normal”
reflex-	Latin reflexus, from reflectere	”Bent back,” “turned back” — from re- (“back”) + flectere (“to bend”)
-ia	Greek -ία (-ía)	Noun-forming suffix — “condition of,” “state of”

Literally: “condition of excessive bending back” — describing the exaggerated return response of a reflex arc. The term reflex entered medical Latin via the 17th century, formalized by René Descartes in his mechanistic model of involuntary nervous response. The prefix hyper- was attached in the late 19th century as neurological examination techniques became standardized.

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🔀 ALIASES / ALTERNATE TERMS

Term	Context
Autonomic dysreflexia	Preferred clinical/ICD-10 term for autonomic hyperreflexia in SCI ≥T6
Autonomic hyperreflexia	Older/synonymous term for autonomic dysreflexia
Detrusor hyperreflexia	Older urodynamic term → now neurogenic detrusor overactivity (NDO)
Uninhibited neurogenic bladder	ICD-10 mapped term for suprasacral detrusor hyperreflexia
Exaggerated deep tendon reflexes	Clinical description; mapped to R29.2 (Abnormal reflex)
Pathological hyperreflexia	Descriptor for reflex exaggeration beyond physiological bounds
Clonus	Rhythmic reflex oscillations; extreme form of hyperreflexia
Spastic hyperreflexia	Hyperreflexia in context of UMN spasticity syndrome

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🔗 RELATED TERMS

• Clonus — sustained rhythmic muscular contractions from severe hyperreflexia; tested at ankle/wrist
• Babinski sign — pathological plantar reflex (upgoing toe); corticospinal tract sign co-occurring with hyperreflexia
• Spasticity — velocity-dependent increase in muscle tone; frequently accompanies hyperreflexia in UMN syndrome
• hyporeflexia — diminished reflexes; the opposite finding; seen in LMN or peripheral nerve disease
• Areflexia — complete absence of reflexes; acute spinal shock or peripheral neuropathy
• Upper motor neuron (UMN) syndrome — clinical cluster of hyperreflexia, spasticity, Babinski, weakness
• Autonomic dysreflexia — life-threatening autonomic reflex storm in SCI ≥T6; mapped to G90.4
• Neurogenic detrusor overactivity (NDO) — bladder-specific hyperreflexia post suprasacral lesion
• Detrusor sphincter dyssynergia (DSD) — simultaneous detrusor contraction + sphincter contraction; common with hyperreflexia
• Spinal cord injury (SCI) — most common cause of both autonomic and detrusor hyperreflexia
• Multiple sclerosis (MS) — demyelinating cause of UMN hyperreflexia and bladder hyperreflexia
• stroke / cerebral infarction — UMN lesion causing contralateral hyperreflexia
• cerebral palsy — developmental UMN cause of spastic hyperreflexia
• ALS (Amyotrophic Lateral Sclerosis) — mixed UMN/LMN disease; hyperreflexia prominent in early UMN phase
• Urodynamics — diagnostic testing modality for detrusor hyperreflexia/NDO

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CODING CORNER

🏥 ICD-10-CM CODES

Symptom Code — Somatic Hyperreflexia (Abnormal Reflex)

Code	Description
R29.2	Abnormal reflex (use when hyperreflexia is documented as a finding without a specific underlying neurological diagnosis; a CC under MS-DRG grouping)

Autonomic Dysreflexia (Autonomic Hyperreflexia)

Code	Description
G90.4	Autonomic dysreflexia (code first the underlying spinal cord condition; sequence the triggering condition as additional code per ICD-10-CM instructional note — e.g., bladder distension, fecal impaction, pressure ulcer)

Bladder Hyperreflexia / Neurogenic Detrusor Overactivity

Code	Description
N31.0	Uninhibited neuropathic bladder, not elsewhere classified (suprasacral lesion — the ICD-10-CM equivalent of detrusor hyperreflexia/NDO)
N31.1	Reflex neuropathic bladder, not elsewhere classified (complete suprasacral SCI with no voluntary control)
N31.2	Flaccid neuropathic bladder, not elsewhere classified (infrasacral/LMN lesion — hyporeflexic bladder; contrast with N31.0/N31.1)
N31.8	Other neuromuscular dysfunction of bladder (use when NDO doesn’t fit N31.0-N31.2 exactly; e.g., mixed pattern)
N31.9	Neuromuscular dysfunction of bladder, unspecified
N32.81	Overactive bladder (non-neurogenic OAB; distinct from neurogenic detrusor overactivity — do not conflate)

Common Underlying Causes to Code Concurrently

Code	Description
G90.4	Autonomic dysreflexia (SCI-associated; code with triggering stimulus)
50 Medical Coding/ICD-10 Codes/G11.4	Hereditary spastic paraplegia (UMN hyperreflexia)
G04.1	Tropical spastic paraplegia (UMN hyperreflexia)
K59.2	Neurogenic bowel, not elsewhere classified_(frequently coded with G90.4 as the triggering condition)_

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🔧 COMMON CPT CODES (Hyperreflexia Evaluation & Management)

Neurological Evaluation

CPT Code	Description
95923	Testing of autonomic nervous system function; vasomotor adrenergic innervation (including any pharmacologic agents)
95924	Testing of autonomic nervous system function; cardiovagal innervation and vasomotor adrenergic innervation
95925	Short-latency somatosensory evoked potential study, upper extremity
95926	Short-latency somatosensory evoked potential study, lower extremity
95927	Short-latency somatosensory evoked potential study, trunk or head

Urodynamic Testing (Detrusor Hyperreflexia/NDO Workup)

CPT Code	Description
51726	Complex cystometrogram (CMG) (primary urodynamic test for NDO/detrusor hyperreflexia — documents uninhibited contractions)
51725	Simple cystometrogram
51727	Complex cystometrogram with urethral pressure profile studies
51728	Complex cystometrogram with voiding pressure studies (VP)
51729	Complex cystometrogram with voiding pressure studies and urethral pressure profile studies
51736	Simple uroflowmetry (UFR)
51741	Complex uroflowmetry
51784	Electromyography studies of anal or urethral sphincter (EMG for DSD — detrusor sphincter dyssynergia evaluation)
51785	Needle electromyography studies of anal or urethral sphincter

Treatment — Botulinum Toxin Injection for NDO

CPT Code	Description
52287	Cystourethroscopy with injection(s) for chemodenervation of the bladder (OnabotulinumtoxinA / Botox injection for NDO — primary treatment for detrusor hyperreflexia refractory to anticholinergics)

Spasticity Treatment (Somatic Hyperreflexia)

CPT Code	Description
64644	Chemodenervation of one extremity; 1-4 muscle(s) (e.g., botulinum toxin for spastic hyperreflexia)
64645	Chemodenervation of one extremity; 5 or more muscles
64646	Chemodenervation of trunk muscle(s)
62350	Implantation, revision or repositioning of tunneled intrathecal or epidural catheter (for intrathecal baclofen pump — severe spasticity/hyperreflexia)
62362	Implantation or replacement of device for intrathecal or epidural drug infusion; programmable pump, including preparation of pump (intrathecal baclofen pump implant for spasticity)

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⚠️ Coding Note: G90.4 (Autonomic dysreflexia) carries an ICD-10-CM instructional note to code first the underlying spinal cord disorder and to use additional code to identify the condition causing the dysreflexia (e.g., fecal impaction K56.41, pressure ulcer, catheter-associated UTI T83.511A). This is a high-yield inpatient query: autonomic dysreflexia in a paraplegic/quadriplegic patient presenting with hypertensive urgency is frequently undercoded. N31.0 (uninhibited neuropathic bladder) is the ICD-10-CM mapping for detrusor hyperreflexia/NDO — note that N32.81 (overactive bladder) should not be used for neurogenic overactivity; it is reserved for idiopathic OAB without neurological cause. For urodynamics, 51726 (complex CMG) is the workhorse code for NDO documentation; when combined with electromyography (51784) and voiding pressure (51728), this constitutes a full urodynamic study — confirm each service is separately documented. Botulinum toxin bladder injection (52287) requires the HCPCS code for the drug (J0585 — onabotulinumtoxinA) billed separately on the claim. R29.2 functions as a CC under MS-DRG when documented without a more specific neurological etiology.

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DERIVATIONS of hyperreflexia

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Query functionality

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Med terms dictionary Appendix A Prefixes Appendix B Combining Forms Appendix C Suffixes Appendix D Suffix forms