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Myotonic discharges and its EMG significance

Generator :  of Myotonic discharges  is Muscle membrane
Sound : It is identified by the Diving Bonder / motorcycle rewing sound while doing EMG
Firing pattern: Myotonic discharges  has Waxing and waning firing pattern
What are the conditions where you see Myotonic discharges?
1.Myotonic discharges in  neurogenic disorders
  • Chronic or longstanding axonal peripheral neuropathies (foot/distal muscles)
  • Chronic or old, severe radiculopathies
Usually long, change of firing rate (waxing/waning) is slow
Increase in firing rate  can distinguishes it from a rapidly waning fibrillation potential
2.Myotonic discharges – along with clinical myotonia
  • Myotonic dystrophy   
         Type 1
         Type 2
In this condition Myotonia less prominent with repetitive contraction
  • Myotonia congenita
  • Paramyotonia congenita-In this condition Myotonia increase following repetitive contraction
3.Myotonic discharges without clinical Myotonia
  •  Hyperkalemic periodic paralysis
  •  Emery-Dreifuss muscular dystrophy
Infrequently in:
  • Inflammatory myopathies
  • Medication induced (statins)

Method of Cardiac Auscultation

Patient is asked to be in supine position or in propped up position if orthopnoea present. The conventional sequence of auscultation of areas - Mitral area - tricuspid area - pulmonary area - aortic area - second aortic area

One should start auscultating mitral area with bell, then with diaphragm of stethoscope. For better appreciation, patient can be put in left lateral position.

Mitral area
Search for abnormality of S1 and presence of S3, S4, Opening snap and mitral systolic and diastolic murmur, conduction of systolic murmur to axilla

Tricuspid area 
You should look for diastolic and systolic murmurs of tricuspid valve disease, augmentation with inspiration in the sitting position is noticed

Pulmonary area 
Identify the abnormality of S2, alteration in intensity and split, ejection click, systolic, diastolic and continuous murmur

Aortic area 
Ask the patient to be in the sitting posture ,leaning forward and breath held in expiration. Look for intensity of aortic component of S2, aortic, systolic and early diastolic murmur

Second aortic area 
Sometimes aortic events are better heard in the 2nd aortic area and the position of the patient is as above. 

Symptomatology in cardiovascular disorders

Presenting symptoms in chronological order include

  1. Dyspnoea
  2. Palpitation
  3. Chest pain
  4. Cyanosis
  5. Edema
  6. Syncopal attack
  7. Cough
  8. Cough due to recurrent respiratory infection as in Mitral valvular disease, left to right shunt
  9. Nocturnal cough in PND
  10. Cough with pink frothy sputum in pulmonary edema.
  11. Hemoptysis
  12. Fatigue.
  13. Fever
  14. Joint pain

Importance of joint involvement in cardiovascular system :

  1. Acute rheumatic fever
  2. Rheumatoid arthritis. SLE. ankylosing spondylitis may be associated with Aortic or mitral regurgitation
  3. Infective endocarditis

Lacrimatory pathway

Following are the components of the lacrimatory pathway
  • Lacrimatory nucleus  facial nerve.
  • Greater superficial petrosal joins with deep petrosal nerve to form nerve of pterygoid canal  which pass through the pterygopalatine fossa where there is pterygopalatine ganglion.
  • Zygomatic branch of maxillary nerve.
  • Zygomaticotemporal nerve.
  • Communicating branch to lacrimal nerve - lacrimal gland.The lacrimal nerve is  derived from the ophthalmic nerve and it innervate the sensory component of the lacrimal gland.

Features of Posterior interosseous nerve injury

  • A lesion of the PIN causes weakness of finger extension (finger drop) without wrist drop.
  • The wrist deviates radially on extension due to weakness of the PIN innervated extensor carpi ulnaris  muscle with preservation of the main trunk innervated extensor carpi radialis longus muscle.
  • Some of the fingers may be affected more than others most often the ring and small fingers are selectively dropped, producing an abnormal posture which will  superficially resembles an  ulnar griffe (pseudoulnar claw hand).
  • Sometimes, cervical radiculomyelopathy will also selectively drop the ring and small fingers (Ono's hand, myelopathy hand, pseudopseudoulnar claw hand).
  • A PIN lesion is not associated with sensory changes.
  • Neuropathy of the superficial radial nerve will cause pain and alterations of sensation in its
  • distribution; it may be injured by tight bands around the wrist 

Significance of hand examination in systemic diseases

Examination of hand reveals specific features of systemic diseases.
  • Cold clammy hand with peripheral  cyanosis indicate shock
  • Cold moist hand in anxiety state
  • Cold dry hand is a feature of myxedema
  • Warm moist hand seen in thyrotoxicosis
  • Pallor of palmar crease observed in anemia
  • Wasting and fasciculation of hand muscles- is seen MND, syringomyelia
  • Myotonic disorders can be associated with slow relaxation on shaking hand
  • Cyanosis and clubbing together-Cyanotic CHD, ILD
  • Nail-fold infarct and telangiectasia are seen in vasculitis. SLE, PAN, PSS
  • Osier's node, splinter hemorrhage, Janeway suggestive of infective endocarditis
  • Pigmentation is a feature of Addison's disease, megaloblastic anemia
  • Arachnodactyly is a feature of Marfan's syndrome
  • Deformed hand diagnostic of rheumatoid arthritis 
  • Sclerodactyly in PSS, MCTD
  • Heberden's node are characteristic of osteoarthritis
  • Clawing of hand  in ulnar and median nerve lesion
  • Dupyutren's contracture a feature of alcoholic liver disease, trauma
  • Gottron's papule is seen in dermatomyositis
  • Large spade hand in acromegaly
  • Short 4th metacarpal- pseuda-hypopara thyroidismdism, reverse Marfan's syndrome (Weil-Marchesani syndrome)  and Turner's syndrome
  • Long thumb-fingerization-Holt-Oram syndrome.

Ataxic Gait (Cerebellar Lesion)

  • This gait is also called as reeling. staggering. drunken gait
  • This type of gait is seen in patients with cerebellar lesion and alcohol intoxication
  • The patient is ataxic and reels in any direction, including backwards and walks on a broad base.
  • The unsteady feet are planted widely apart and placed irregularly.
  • The steps are uncertain, some are shorter and some are longer than Intended, and the patient tends to fall or deviate to the side of cerebellar lesion.
  • The ataxia is equally severe whether the eyes are open or closed
  • The patient finds difficulty in executing tandem walking.
  • Gait ataxia is seen in lesion of upper vermis and anterior lobe of cerebellum
  • Titubant ataxia - ataxic gait with vertical oscillation of head and trunk.