MOTOR NEURON DISEASE (MND)

Description

  • Motor neuron diseases or disorders are a heterogeneous group of disorders of motor neurons referring to myriad of diseases manifesting with weakness, wasting and /or spasticity
  • It is a progressive neurological disorder in which motor neurons or the cells that control voluntary muscle activity such as speaking, breathing, swallowing and walking are destroyed 

Spectrum of MND includes

  • Amyotrophic lateral sclerosis(ALS)
  • Progressive muscular atrophy
  • Primary lateral sclerosis
  • Progressive bulbar palsy
  • Juvenile ALS
  • Madras variant MND

The disorder has the following features:

  • Upper motor Neuron involvement : Impaired dexterity of limbs, Generally mild weakness, Stiffness in limbs due to spasticity , Exaggerated deep tendon reflex, Extensor plantar response, Hoffmann sign ,loss of abdominal refelexes
  • Lower motor Neuron involvement :Moderate to severe weakness, Wasting, Fasciculations, Muscle cramp, Reduced or absent deep tendon reflexes

Other motor neuron diseases like spinal muscular atrophy, bulbospinal atrophy have molecular pathology distinct from ALS and, while being motor neuron disorders, are not included as ALS or MND

Etiology

  • Genetic
  • Environmental risk factors : Exposure to pesticides, lead, ß-N-methylamino-L-alanine, smoking etc

Types

Amyotrophic lateral sclerosis:

  • Formerly known as Lou Gehrig disease
  • The disease most commonly manifests between fifty and seventy years of age
  • Both upper motor neuron (UMN) and lower motor neuron (LMN) signs are present
  • Muscle weakness : Two third of patients have typical /spinal form of ALS present with focal muscle weakness of distal or proximal upper limb .It usually starts in one arm and/or leg then progresses to the contra lateral side and eventually, after months or years, affects the respiratory system
  • Muscle cramp: one of the most common symptom
  • Symptoms are highly variable and potentially non-specific (e.g., subtle vocal changes or difficulties grasping objects)
  • About 25% patients present with Bulbar symptoms such as dysarthria, dysphonia, dysphagia and tongue atrophy
  • Some patients presents with weakness that is restricted to one side of the body (Mill’s hemiplegic variant) and 10% patients appear with bilateral upper extremity wasting which is known as flail arm
  • In 1-2 % of patients, weakness starts in respiratory group of muscles and present with dyspnoea on exertion
  • May present with bulbar or pseudobulbar presentation
  • Head drop may be the initial presentation in a small minority of patients
  • Non motor associated symptoms : sleep disturbance , subtle cognitive dysfunction and mood changes

Progressive Muscular atrophy(PMA)

  • s/s of PMA are Lower motor neuron type
  • Focal asymmetrical muscle weakness is seen in distal extremities with gradual progression to other muscles
  • Ultimately involves both upper and lower limbs
  • Later : bulbar and respiratory involvement
  • PMA needs to be differentiated from Spinal muscular atrophy(SMA) 

Primary Lateral sclerosis

  • Rare Motor neuron disease that accounts for 2-4% of all cases of MND
  • Distinguished by a lack of LMN involvement
  • UMN involvement during entire course
  • Slowly evolving spastic paraparesis later involving upper limbs

Progressive bulbar palsy

  • Disease that attacks the bulbar muscles. Characterized by the degeneration of motor neurons in cerebral cortex, spinal cord, brainstem, and pyramidal tracts
  • Specifically involves the glossopharyngeal nerve, vagus nerve and hypoglossal nerve
  • Caused by LMN lesions
  • Symptoms include difficulty in chewing, talking and swallowing ,Difficulty in pronunciations of words which need lip movement and dental coordination
  • Drooling of saliva and fasciculations with wasting of tongue
  • Reduced gag reflex and weak movements of facial muscles and tongue. Weakness involve respiratory muscles later

Pseudobulbar palsy

  • Bilateral impairment of lower cranial nerves due to UMN lesions of the bulbar muscles
  • Spastic dysarthria, dysphonia, dysphagia (usually milder in Bulbar palsy)
  • Emotional lability (inappropriate or forced crying or laughter)
  • Brisk jaw jerk
  • Hyperactive gag reflex

Madras motor neuron disease

  • Unique geographic distribution predominantly reported from Madras
  • Onset in young. Weakness & wasting of limbs are the first presentation
  • Sensorineural hearing loss is predominant initial manifestation
  • Optic atrophy

Juvenila ALS

  • Young onset MND with UMN and LMN symptoms
  • Choreic movements, cerebellar taxia, and mental retardation in the absence of deafness

Investigation

  • EMG: denervations seen as fibrillations, positive sharp waves, fasciculations
  • Creatinine kinase: normal or elevated upto four times
  • MRI: reduced T2 intensity in motor cortex
  • NCS

Treatments

Focus on retaining function and improving quality of life

Internal medicines

  • Bhadradarvadi kashaya
  • Rasonadi kashaya
  • Ashtavarga kashaya
  • Brahmi drakshadi kashaya
  • Svarna muktadi vati
  • Vatavidhwamsani rasa
  • Sidha makaradwaja
  • Sapippalika yoga
  • Saraswatha choorna
  • Kapikachu choorna
  • Aswagandha choorna
  • Ksheerabala taila
  • Sahacharadi vasti paka
  • Chyavanaprasha

Procedures

  • Udvartana – Jeevanthyadi choorna
  • Abhyanga - Mahamashadi /Sahacharadi
  • Shashtika pinda sweda
  • Mamsa pinda sweda
  • Vasti – Mustadi raja yapana vasti
  • Talam – Rasnadi choorna + Nimbamruta eranda

Department

Kayachikitsa

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