Motor Neuron Disease (MND): Pathology, Clinical Presentation, and Physiotherapy Management

1. Overview and Classification

• Adams and Victor's Principles of Neurology, 12th Edition

2. Pathology

2.1 Gross Pathology

• Atrophy of the cerebral precentral gyrus (motor cortex)
• Sclerosis and pallor of the corticospinal tracts of the spinal cord (the "lateral sclerosis" of the name)
• Thinning of the hypoglossal nerves and ventral spinal roots
• Obvious muscle atrophy

2.2 Microscopic Pathology

• Loss of at least 50% of spinal motor neurons with diffuse astrocytic gliosis in the spinal gray matter
• Cardinal feature: ubiquitinated proteinaceous inclusions in residual motor neurons - compact or skein-like, with TDP-43 recognized as a major protein constituent
• Motor cortex: variable loss of upper motor neurons (Betz cells) and astrocytic gliosis
• Corticospinal tracts: axonal loss, myelin pallor, and gliosis
• Skeletal muscle: clusters of angular atrophic fibers and fiber-type grouping from serial denervation and reinnervation

2.3 Relative Sparing

• Onuf's nucleus (sacral cord - innervates pelvic floor) - explaining preserved continence
• Cranial nerve nuclei III, IV, VI (extraocular muscles) - eyes are spared until very late disease

2.4 Molecular Pathogenesis

• Genetic mutations: ~5-10% of ALS is familial; the best-characterized is SOD1 (superoxide dismutase 1), accounting for 20% of familial cases. Other genes include C9ORF72 (most common familial cause), TARDBP (TDP-43), FUS/TLS, TBK1, FUS, VAPB, alsin, and senataxin
• C9ORF72 hexanucleotide repeat expansion: produces characteristic cerebellar and hippocampal P62+/TDP-43-negative inclusions and is associated with concurrent frontotemporal dementia
• Pathogenic mechanisms include:
  • Oxidative stress (mutant SOD1 aggregation)
  • Excitotoxicity (excess glutamate - basis of riluzole therapy)
  • Protein aggregation and impaired axonal transport
  • Mitochondrial dysfunction
  • Prion-like propagation of misfolded SOD1 and TDP-43 between cells
  • Non-cell-autonomous toxicity from mutant astrocytes and microglia on neighboring motor neurons
• Goldman-Cecil Medicine International Edition; Adams and Victor's Principles of Neurology, 12th Ed.

3. Clinical Presentation

3.1 Onset and Early Features

• Onset is typically insidious, perceived as weakness in a distal limb
• Common early presentations:
  • Unexplained tripping from foot drop
  • Awkwardness in fine finger movements (buttons, keys)
  • Stiffness, slight weakness, or wasting of hand muscles (usually unilateral at first)
  • Volitional cramping (e.g., leg cramps turning in bed)
  • Fasciculations of forearm, upper arm, and shoulder girdle muscles
• ~75% of patients begin with focal, distal, asymmetric limb onset; the remainder present with bulbar symptoms (dysarthria, dysphagia) or, rarely, respiratory symptoms first

3.2 Upper Motor Neuron (UMN) Signs

• Hyperreflexia (brisk tendon reflexes - paradoxically present even in wasted limbs)
• Increased muscle tone / spasticity
• Babinski sign
• Pseudobulbar affect (uncontrollable laughing or crying - pseudobulbar palsy)
• Brisk jaw jerk, slowed repetitive tongue movements, strained effortful speech

3.3 Lower Motor Neuron (LMN) Signs

• Weakness and muscle wasting (amyotrophy)
• Fasciculations (visible muscle twitching, including tongue)
• Reduced or absent reflexes in severely wasted muscles

3.4 Bulbar Involvement

• Dysarthria progressing to anarthria
• Dysphagia - liquids and small food particles aspirated into trachea or nose
• Tongue: fasciculations and focal atrophy early; eventually shriveled and functionless
• Facial weakness (lower face predominantly)
• Jaw clonus in severe spasticity

3.5 Respiratory Involvement

• Develops insidiously - rarely the initial feature
• Dyspnea on exertion, then at rest; orthopnea
• Diaphragmatic weakness: paradoxical abdominal wall movement during inspiration; marked FVC decline in supine position
• Nocturnal CO2 retention: disrupted sleep, morning headaches, anorexia, daytime somnolence

3.6 Neck and Axial Features

• Neck muscle weakness causing dropped head syndrome
• Extraocular muscles are preserved even in advanced disease - patients may communicate only via eye movements

3.7 Cognitive/Behavioral Features

• Overt frontotemporal dementia in ~5% of ALS patients
• Up to 50% show subtle frontal lobe dysfunction without overt dementia
• C9ORF72-ALS particularly associated with cognitive disturbance and family history of dementia

3.8 Preserved Functions

• Bladder/bowel continence usually preserved (Onuf's nucleus spared)
• Sensory examination and mental status typically normal
• Eye movements preserved until very late

3.9 Disease Course and Prognosis

• Median survival: 23-52 months from symptom onset
• Earlier bulbar involvement predicts shorter survival
• PLS (pure UMN): survival commonly 10-15 years
• Progressive weight loss and fatigue are consistent features
• Death typically from respiratory failure or aspiration pneumonia
• Neuroanatomy through Clinical Cases, 3rd Edition; Goldman-Cecil Medicine

4. Diagnosis

1. Evidence of LMN loss (EMG: reduced interference pattern, increased firing rate)
2. Evidence of reinnervation (large, long-duration motor units)
3. Fibrillation, sharp waves, or fasciculation potentials
4. Evidence of UMN degeneration by clinical examination
5. Progressive spread of symptoms/signs within or across regions (bulbar, cervical, thoracic, lumbosacral)
6. Absence of other explanatory disease processes

5. Physiotherapy Management

5.1 Assessment and Outcome Measurement

• Muscle strength testing (MRC grading, hand-held dynamometry)
• Functional mobility and gait analysis
• Forced Vital Capacity (FVC) - key respiratory measure (NIV indicated when FVC <50%)
• ALSFRS-R (ALS Functional Rating Scale Revised) - tracks disease progression
• Pain assessment (VAS/NRS)
• Balance and falls risk assessment
• Fatigue measures (fatigue severity scale)

5.2 Goal Setting

• Early stage: Maximize function, prevent complications, maintain independence
• Middle stage: Adapt and compensate for deficits, prescribe aids and appliances
• Late stage: Comfort, symptom management, caregiver education, palliative support

5.3 Exercise Prescription

• Moderate-resistance exercise targeting muscles with MRC grade 3 or above
• Evidence suggests moderate-intensity resistance training is safe and effective in early to mid-stage disease
• Avoid exercising to fatigue; monitor for post-exercise fatigue/soreness
• Use of free weights, resistance bands, gym equipment (adapted as needed)

• Low-to-moderate intensity aerobic exercise (cycling, walking, swimming)
• Benefits include improved cardiovascular endurance and quality of life
• Aquatic exercise is well-tolerated due to reduced load on weakened muscles

• Daily passive and active-assisted stretching to prevent contractures
• Particular attention to: shoulder, elbow, wrist/hand, hip flexors, knee flexors, ankle plantarflexors

• Activity pacing strategies
• Energy conservation education
• Scheduling rest periods within daily routine

5.4 Spasticity Management

• Regular passive stretching and range of motion exercises
• Positioning to prevent spastic posturing
• Hydrotherapy / warm water immersion to reduce tone
• Splinting and orthoses (e.g., resting hand splints, ankle-foot orthoses)
• Transcutaneous electrical nerve stimulation (TENS) may provide symptomatic relief

5.5 Respiratory Physiotherapy

• Breathing awareness training and diaphragmatic breathing
• Inspiratory muscle training (IMT) using threshold devices - shown to improve inspiratory pressure
• Resistance breathing exercises
• Breathing-relief posture training

• Manual assisted cough techniques (taught to patient and carer)
• Mechanical insufflation-exsufflation (MI-E / "CoughAssist"): most effective for clearing secretions when peak cough flow <270 L/min
• Controlled coughing techniques
• Postural drainage (caution with respiratory compromise)
• Chest percussion and vibration

• NIV (BiPAP) initiated when FVC <50%, orthopnea is present, or SpO2 <95% nocturnally
• Physiotherapist assists with NIV mask fitting, tolerance training, and troubleshooting

5.6 Mobility and Functional Aids

• Walking aids: walking stick, rollator/wheeled walker
• Ankle-foot orthoses (AFOs): for foot drop
• Wrist/hand splints: to maintain functional hand position
• Cervical collar or head support: for dropped head syndrome
• Wheelchair assessment and prescription: powered or manual, appropriate seating and postural support
• Hoists and transfer aids: as mobility declines

5.7 Pain Management

• Joint mobilization and gentle manual therapy for periarticular stiffness
• Splinting and positioning to address frozen shoulder and joint contractures
• TENS for neuropathic or musculoskeletal pain
• Postural correction and support

5.8 Falls Prevention

• Balance training exercises (tailored to stage)
• Environmental assessment and home modification advice
• Patient and carer education on safe transfers
• Regular mobility reassessment as disease progresses

5.9 Communication and Multidisciplinary Liaison

• Regular reassessment and documentation with the MDT
• Timely referral for PEG/gastrostomy (when FVC >50% - safer procedure)
• Referral to speech-language therapy as bulbar symptoms develop
• Referral to palliative care team for end-stage management
• Caregiver training in manual handling, passive exercises, and symptom monitoring

5.10 Palliative and End-Stage Physiotherapy

• Comfort positioning and pressure area care
• Passive movements to maintain comfort and prevent contractures
• Breathing support and secretion management
• Psychological support and carer education
• Discussion of advance care planning regarding ventilatory support

6. Pharmacological Management (Context for Physiotherapy Team)

Summary Table: Physiotherapy Goals by Disease Stage

• Adams and Victor's Principles of Neurology, 12th Edition
• Goldman-Cecil Medicine International Edition (Chapter 387)
• Neuroanatomy through Clinical Cases, 3rd Edition
• Macpherson et al. (2026). Physical Therapist Interventions for People With ALS. Physical Therapy [PMID: 41307543] - Systematic Review
• Rehabilitation in ALS: Recommendations for Clinical Practice, JCMS 2025 (based on European Academy of Neurology 2024 guidelines)
• Physiotherapy Guidelines for MND, Irish Hospice Foundation

Recent Evidence Note (2026): A 2026 systematic review (PMID: 41307543) confirms that multimodal physical therapist interventions show moderate-quality evidence for improving ALSFRS-R scores, and pulmonary interventions show small benefits on FVC. Most current evidence is from early-stage ALS populations, and more stage-specific research is still needed.

Neonatal Reflexes: A Detailed Discussion

1. Introduction and Definition

• Survival functions in early neonatal life (feeding, protection, sensorimotor orientation)
• Indicators of normal neurological development - their presence, quality, symmetry, and appropriate disappearance reflect healthy maturation of the central nervous system
• Diagnostic tools - absence, asymmetry, or abnormal persistence is a reliable marker of neurological pathology

"In the normally developing infant, some of these activities disappear as others appear... The absence of these reflexes in the first few months of life and, conversely, their persistence beyond this time indicate a defect in cerebral development."

• Adams and Victor's Principles of Neurology, 12th Edition

2. Overview of Neonatal Reflexes

Quick Reference Table

3. Individual Reflexes - Detailed Description

3.1 Rooting Reflex

• Survival function: Orients the infant toward the food source (breast/bottle nipple)
• Absence or asymmetry: Suggests CNS dysfunction, particularly brainstem pathology. Also seen in prematurity, sepsis, or sedation from maternal medications
• Persistence beyond 4 months: May indicate cortical injury with failure of cortical inhibition

3.2 Sucking Reflex

• Survival function: Essential for feeding and nutrition
• Absent or weak sucking reflex: An indirect indicator of neurological maturity in newborns. When associated with other CNS signs, suggests basal ganglia or brainstem dysfunction
• Clinical note: In a 2011 study, morbidity-related factors statistically correlated with abnormal sucking and Babinski reflexes in high-risk newborns
• Weak in preterm infants: Due to poor muscle tone and immature brainstem circuitry

3.3 Moro Reflex (Startle Reflex)

• Hold the infant supine, pull up by the arms slightly, then suddenly release - the sensation of falling is produced
• Hold infant's head and shoulders off the mat with arms flexed on chest; abruptly let the head and shoulders drop back a few inches

• Phase 1 (abduction/extension): Arms abduct and extend at the shoulders, elbows extend, fingers spread widely with the thumb and index finger forming a characteristic "C" shape
• Phase 2 (adduction/flexion): Arms return toward midline in an embracing motion
• An audible cry typically accompanies the response

• Protective function: Believed to represent a primitive grasping response to prevent falling - an evolutionary remnant of a primate infant's reflex to grasp the mother
• Weak Moro in preterm infants: Due to poor muscle tone and resistance to passive movements; correlates with delayed motor development in very low birth weight infants
• Absent Moro: Strongly suggests CNS dysfunction (bilateral brain injury, brainstem lesion, severe asphyxia)
• Asymmetric Moro (one arm responds, the other does not): Most commonly indicates brachial plexus injury (Erb's palsy - C5/C6), clavicle fracture, or hemiplegia
• Upper motor neuron lesions cause an absent or incomplete Moro
• Persistent Moro beyond 6 months: Indicates failure of cortical inhibition; associated with cerebral palsy or developmental delay

3.4 Palmar Grasp Reflex

• Developmental precursor to voluntary grasp - forms the basis of future hand use and object manipulation
• Weak or absent: Indicates peripheral motor dysfunction (lower brachial plexus injury - Klumpke's palsy C7-T1), spinal cord injury, or severe CNS depression
• Asymmetric palmar grasp: Suggests unilateral neurological deficit (hemiplegia, brachial plexus lesion)
• Persistent beyond 4 months: Indicates failure of cortical development; seen in cerebral palsy

3.5 Plantar Grasp Reflex

• Different from Babinski: Plantar grasp involves all toes flexing; Babinski involves dorsiflexion of the big toe
• Absence: Suggests lower spinal cord pathology (L4-S2 levels)
• Persistence beyond 12 months: Associated with pyramidal tract lesions

3.6 Babinski Reflex (Plantar Reflex)

• Normal in neonates and infants: Represents developmental immaturity of the pyramidal system - should NOT be interpreted as pathological
• After 18-24 months: A positive Babinski becomes pathological and indicates upper motor neuron (pyramidal tract) lesion at any level from motor cortex to spinal cord
• Absent at birth: May indicate depressed CNS function (asphyxia, sedation) or lower motor neuron lesion at the relevant spinal segments
• Adult re-emergence: Seen in stroke, spinal cord compression, multiple sclerosis, and is one of the most important signs in neurology
• Clinical note: Morbidity-related factors in neonates statistically correlate with Babinski reflex abnormalities

3.7 Asymmetric Tonic Neck Reflex (ATNR) - "Fencing Reflex"

• Developmental function: Believed to help develop eye-hand coordination and prepare for unilateral reaching
• Obligatory ATNR (infant locked into the fencer position and cannot break free): Always pathological, indicating cerebral palsy or severe CNS pathology
• Persistence beyond 4-6 months: Associated with spastic cerebral palsy - the reflex interferes with bilateral hand use and midline orientation
• Useful in occupational/physical therapy assessment: Retained ATNR in older children may underlie learning difficulties in reading (difficulty tracking text across midline) and writing

3.8 Symmetric Tonic Neck Reflex (STNR)

• Neck flexion: Arms flex, legs extend
• Neck extension: Arms extend, legs flex

• Developmental function: Helps the infant transition from lying to the hands-and-knees position; facilitates crawling
• Persistent STNR: Interferes with independent crawling; seen in cerebral palsy and developmental coordination disorder

3.9 Stepping (Walking) Reflex

• Developmental precursor to voluntary bipedal locomotion
• Absence: May indicate lower spinal cord pathology, severe hypotonia, or CNS depression
• Asymmetry: Suggests unilateral lesion of the corticospinal system or lumbar plexus
• The fact that this reflex disappears and reappears later as voluntary walking demonstrates that cortical maturation overlays, rather than simply inhibits, these spinal automatisms

3.10 Galant Reflex (Trunk Incurvation Reflex)

• Birth function: Facilitates the infant's passage through the birth canal by enabling lateral flexion
• Absence or asymmetry: Suggests thoracic or upper lumbar spinal cord lesion
• Persistence beyond 3-6 months: Associated with retained primitive reflexes in children; may contribute to fidgeting, poor concentration, and bedwetting in older children with retained Galant due to constant stimulation from waistbands or clothing

3.11 Placing Reflex

• Unlike most other primitive reflexes, the placing reaction is thought to depend on emerging cortical connections - making it more sensitive to cortical lesions
• Absence: One of the early signs of cortical/subcortical pathology in the neonatal period

3.12 Parachute Reflex

• Protective function: Protective extension response to prevent facial injury in falls
• Absent or delayed parachute response: A sensitive indicator of upper motor neuron pathology (cerebral palsy, hemiplegia)
• Asymmetric parachute: Indicates unilateral hemispheric pathology - the affected arm will not extend; highly sensitive sign of hemiplegia
• Critical developmental marker: Should be present by 12 months in all normal infants

3.13 Landau Reaction

• When held in this position, the infant reflexively extends the head, spine, and legs in an arch
• If the head is passively flexed, the legs drop down (Landau's response proper)

• Represents integration of neck righting, labyrinthine, and visual righting reactions
• Absent or weak Landau: Associated with cerebral palsy (especially hypotonic/athetoid types), intellectual disability, and motor developmental delay
• Tests the integrity of anti-gravity extensor function

3.14 Neck Righting Reflex (Body-on-Body Righting)

• Essential precursor to rolling from supine to prone (and vice versa)
• Absence delays rolling milestone; asymmetry suggests hemiplegia

3.15 Doll's Eye Reflex (Oculocephalic Reflex)

• Reflects vestibulo-ocular reflex pathway integrity
• Absent doll's eye reflex in a neonate: Suggests brainstem dysfunction
• Persistent beyond 1-2 months: Indicates failure of cortical visual pursuit to develop

4. Neurological Basis and Cortical Inhibition

1. Fetal period (before term): Brainstem and spinal cord are the dominant neural systems; primitive reflexes develop in utero in a predictable sequence beginning as early as 25-26 weeks gestation
2. Term birth: Full complement of primitive reflexes present; cerebral cortex is immature and not yet exerting inhibitory control
3. 0-6 months: Cortical myelination and synaptogenesis progressively establish inhibitory descending connections; primitive reflexes are suppressed
4. 6-12 months: Postural reflexes (parachute, protective extension, righting reactions) emerge as cortically mediated responses replace primitive brainstem patterns
5. Beyond 12-18 months: Most primitive reflexes absent; re-emergence in adults ("frontal release signs") indicates pathological cortical disinhibition

5. Clinical Significance and Interpretation

5.1 Absent Reflexes

5.2 Persistent (Retained) Reflexes

• Presence of 5 or more abnormal reflexes in a neonate correlates with development of cerebral palsy or mental delays
• Persistent Moro beyond 6 months: Cerebral palsy; in older children, associated with hypersensitivity to sensory stimuli
• Obligatory ATNR beyond 4 months: Cerebral palsy (spastic); interferes with bimanual tasks, midline orientation, and reading
• Persistent palmar grasp: Cerebral palsy; interferes with voluntary object release
• Persistent Galant: May contribute to fidgeting, poor attention, and enuresis in school-age children
• Persistent STNR: Interferes with crawling and sitting; associated with developmental coordination disorder

5.3 Adult Re-emergence ("Frontal Release Signs")

6. Assessment Scales Using Neonatal Reflexes

Brazelton Neonatal Behavioral Assessment Scale (NBAS)

APGAR Score (indirect)

Neurological Examination of Newborn (Prechtl and Beintema)

7. Practical Notes for Assessment

• State of alertness matters: Reflexes are best elicited in a quiet, alert state. Crying, sleeping, or feeding may alter reflex expression
• Gestational age: Preterm infants have weaker or incomplete reflexes - always interpret in context of corrected gestational age
• Symmetry is key: Asymmetric responses are more significant than bilaterally reduced responses
• Sequence of disappearance: Reflexes disappear in a predictable order; deviations are diagnostically meaningful
• Combination of findings: A single abnormal reflex has less weight than multiple abnormal reflexes together

Summary: Developmental Timeline of Key Neonatal Reflexes

Birth ────────────────────────────────────────────── 18 months

|─── Rooting (0-4 months)
|─── Sucking (0-4 months, then voluntary)
|─────── Moro/Startle (0-6 months)
|─────── Palmar Grasp (0-4 months)
|─────────── ATNR (0-4 months)
|─────────── Stepping (0-2 months)
|── Galant (0-2 months)
|────────────────────────── Babinski (0-18 months normal)
|────────────────────────── Plantar Grasp (0-12 months)
                  |──── Parachute (7 months → lifelong)
                  |──── Landau (3-24 months)
                  |──── Neck Righting (4-6 months)

• Adams and Victor's Principles of Neurology, 12th Edition - Chapter 27: Development during the Neonatal Period
• Textbook of Family Medicine, 9th Edition - Table 21-5: Primitive Neurologic Reflexes in Newborns
• Neuroanatomy through Clinical Cases, 3rd Edition
• Modrell & Tadi. Primitive Reflexes, StatPearls, NCBI Bookshelf (2023)
• Sohn (2011). Assessment of Primitive Reflexes in High-risk Newborns. Journal of Clinical Medicine Research