Muscle biopsy is an essential test for assessing patients with suspected myopathies. It provides valuable information about muscle fiber morphology, pathology distribution, and can help distinguish between neurogenic and myopathic processes. Key diagnostic features on biopsy can confirm or clarify the clinical diagnosis. Proper biopsy technique and handling of the sample are important for optimal histological and molecular analysis.

1. Muscle biopsy
Dr. Rahi Kiran. B
SR Neurology

2.  it is an essential element in the assessment of a
patient with suspected myopathy.
 The history 1860 when Duchenne first performed a
biopsy on a patient with symptoms of myopathy.
 time for biopsy, muscle to select, how many specimens
to obtain, and how to handle the specimen are
individualized

3. EPIMYSIUM
•Loose CT
•Blood vessels
PERIMYSIUM
•Septa
•Nerve branches
•Muscle spindles
•Fat
•Blood vessels
ENDOMYSIUM
•Muscle fibers
•Capillaries
•Small nerve fibers

4. General reasons:
 Weakness of uncertain cause-generalised, proximal
 floppy infant syndrome
 Muscle pain ,cramps, stiffness
 Persistently elevated muscle enzymes(CK)

5.  Specific reasons:
 Hereditary muscle disease in other family members - Carrier detection
 metabolic diseases such as storage disease
 Suspicion of steroid myopathy in treated myositis - Exclude drug induced
myopathy
 Conflicting clinical ,EMG or lab findings
 to distinguish between myopathy and neuropathy.
 Confirm/reinforce clinical diagnosis

6.  A normal biopsy in pt with high level of clinical suspicion of
a myopathy
 patient with known inflammatory myopathy who, after
improvement with steroid therapy, develops increasing
weakness.
 Biopsy findings can help distinguish between recurrence of
the inflammatory disorder and steroid myopathy.

7. 1. Bleeding disorder
2.Most endocrine myopathies
3.Malignant hyperthermia
4.Poor nutrition
5.Prior Trauma

8. • Muscle with moderate disease, NOT severe
• Muscle belly, not from tendon
• Proximal myopathies/generalised systemic disease- Vastus
Lateralis
• Other sites-Biceps,gatronemius
• Avoid Deltoid,muscle that are site of EMG,injections/trauma
• Imaging used to select pathological muscle site in difficult cases.

9. Technique
1.Needle Biopsy
2.Open Biopsy- indicated for
disorders with patchy pathology

10.  Sample size: 0.5 cm diameter
1cm length
 Biopsy is processed:
1.Paraffin embedding
2.Histochemistry
3.For electron microscopy
4.For molecular biology

11.  The sample can be sent to the laboratory on saline gauze in a
sealed container on ice
 should not be immersed
 Ideally, immediately transported to the laboratory for
processing
 Fixed in paraformaldehyde, 3% glutaraldehyde, 10% formalin

12. Fresh Fixed
Muscle may be saved in saline moistened guage for several hrs
Keep the specimen cool
Do NOT immerse in saline ,fixative or other liquid
Glutaraldehyde, 4degree
EM ( 1mm x 0.5 cm)
Formalin
PARAFFIN (0.5x0.5cm)
inflammatory myopathies, vasculitis
Snap freeze
HISTOCHEMISTRY
(0.5x0.5cm) stains
Gel electrophoresis
western blot

13.  trauma to the muscle- disrupts architecture
 Electrocautery should not be used
sample coagulated by the application
of electrocautery
contraction band artifact

15. Perimysial
connective tissue
Endomysial
connective tissue
Note uniform sizes, polygonal shapes, and eccentric nuclei.

16. Normal muscle Adult Normal Muscle child

18. OIL RED O

19. H & E
Used to evaluate gen architecture of muscle and
variation in morphology of individual fibres
•Variation in fascicular architecture
•Variation in fiber size
•Necrosis and degeneration of muscle fibres
•Nuclear characteristics
•Type & distribution of inflammatory infiltrate
•Interstitial changes

20. Normal Internalisation of nuclei

21. • Myotonic dystrophy
• LGMD
• Myotendinous insertion
• Centronuclear myopathy
• Chronic neuropathies - jSMA
(60%)

22.  Fibrosis - all types of dystrophies and central core disease

23. •Limb girdle dystrophy
•Myotonic dystrophy

24.  Duchene muscular dystrophy
A hyalinised fiber is a fiber which has lost its cross
striations, has homogenous pale
Cytoplasm, Usually these fibers are rounded.

25. •Limb girdle muscular dystrophy
•Chronic neuropathies

26.  pale stained on H&E and infiltrated by phagocytes
(myophagocytosis) - DMD
Fiber necrosis Perifascicular necrosis

27. Pathologic features Disease
Small groups of necrotic
fibres
DMD
Perifascicular necrosis Dermatomyositis
Random fibre necrosis PM,IBM
Extensive,diffuse Rhabdomyolysis

28. Nuclear inclusions:
Oculopharyngeal dystrophy
Sarcoplasmic Inclusions:
Myofibrillar myopathy
Inclusion body myositis

29. Pathologic feature Disease
Perivascular, angiocentric DM, connective tissue
disease ,FSHD
Endomysial, around
fibres
PM, IBM,viral
Nodular Rheumatoid arthritis,
granuloma
Polymorphs with
eosinophils
PAN, drug reactions,
trichinosis, eosinophilic
fascitis

31. Type 1 fiber atophy Type 2 fiber atophy
•Myotonic dystrophy
•Nemaline myopathy
•Centronuclear myopathy
•Congenital fibre type
disproportion
Corticosteroid therapy
Myasthenia Gravis
Disuse Atrophy
Acute denervation
Paraneoplastic myopathy
Pattern of atrophy:
Grouped atrophy Chronic neurogenic disorders
Panfascicular ISMA(Infantile spinal muscular atrophy)
Perifascicular DM(Dermatomyositis)

32. Normal Atrophy

33. Denervation. Chronic denervation and reinnervation

34. Type 1 fiber
hypertrophy
Type 2 fiber
hypertrophy
Type 1&2 fiber
hypertrophy
ISMA
Normal Atheletes
Sprinters Limb girdle
dystrophy,IBM,myotonia
congenita,acromegaly
Normal Hypertrophy

35. Normal muscle-polygonal
Angular-neurogenic Rounded-myopathic

36. recognition of split fibers
is by a thin fibrous
septum, often
associated with a
nucleus that crosses
partway but not all the
way across the fiber.

37. modified Gomori’s trichrome (MGT) stain

38.  PH 9.4 - type 1 fibers - pale ,
type 2 fibers – dark,
viceversa at 4.6
 Type predominance – if > 55% (1, 2A,2B),
>80% - type 2

40.  Type 1 - normal in the gastrocnemius and deltoid muscles,
hallmark of congenital myopathies and many of the
early dystrophies.
 Type 2 - lateral head of the quadriceps muscle,
jSMA, MND

41.  Type 1 fiber atrophy - myotonic dystrophy type 1,
congenital myopathies and dystrophies
 Type 2 fiber atrophy - common , non specific –
chronic corticosteroid administration,
disuse,
RA, CTD,
Cancer,
mental retardation,
myasthenia gravis

42. Creatine kinase level: To rule out certain categories of myopathies
because different myopathies tend to generate a different levels of
elevation in CPK.
•High: (e.g. Dystrophinopathies) 200-300 times of normal.
•Intermediate: (e.g. Inflammatory myopathy) 20-30 times of normal.
•Low: (e.g. Neurogenic disorder) 2-5 times of normal.

43.  Lab. – Serum CK : elevated 20-100x normal
 EMG : myopathic features
 Muscle biopsy- Fiber necrosis & regeneration
Variation in fiber size,
internalisation of nuclei
proliferation of endomysial connective tissue.
Deficiency of dystrophin seen on
western blot analysis & IHC staining
DNA analysis : mutation of gene that encodes dystrophin

44. • Lab. – CK : elevated
-EMG : myopathic
- muscle biopsy : similar to DMD
: reduced amount or abnormality of
dystrophin( Dx)
- DNA analysis : deletions or duplications( Dx)

45. DMD
End stages-extensive
replacement
by adipose tissue and
fibrosis

46. • Lab. – Dx ; usually based on clinical findings
-CK : N or mildly elevated
-EMG : evidence of myotonia
-Biopsy : variation in fiber size,
increase in internal
nuclei(chains) ring,
selectively involves type – 1 fiber in 50%
Myotonic dystrophy

47. • Lab.– EMG: myopathic features
-CK : 2-3x N
-BIOPSY : presence of tubular filaments in muscle
cell nuclei,
mild dystrophic changes with nuclear
internalisation ,fiber atrophy,
Interstital fibrosis,
rimmed vacuoles in type 1 fibres

48. • Lab. – CK : N or elevated
- EMG: myopathic pattern
- BIOPSY: Atrophic muscle fibres in
clusters/groups in absence of necrosis,
- Moth eaten fibres and perivascular
inflammatory infiltrate

49. PM DM IBM
Muscle Biopsy “primary”
inflammation with
the CD8/MHC-I
complex & vacuoles
Endomysial
inflammation
Perifascicular,
perimysial, or
perivascular
infiltrates,
perifascicular atrophy
inflammatory
reactions
around blood vessels,
Primary inflammation
with CD8/MHC-I
complex; vacuolated
fibers with
b-amyloid deposits ,
Endomysial
inflammation

50.  Perifascicular atrophy
 Degeneration
 Inflammatory cells in the perimysium
surrounding a blood vessel

51. Congenital myopathies
1.Central core disease
2.Multicore disease
3.Nemaline(Rod) myopathy
4.Centronuclear myopathy
5.Congenital fibre type disproportion
• Lab. - CK: usually N or slightly elevated
- EMG : myopathic, myotonic discharges
- Biopsy : features specific to each type

52. •AD
•Biopsy- cytoplasmic cores
in type 1 Fibres – also in
HOCM
(NADH-TR stain)

53. •Cong non progressive myopathy(gen weakness,hypotonia)
•Biopsy –type 1 fiber predominance& minute core like
structures in majority of fibres

54. • AR/AD
• Aggregates of spindle shaped
particles(nemaline rods) occur
predominantly
 In type 1 fiber best seen MGT stain
Detected by MGT

55. •AD/AR/XL
•BIOPSY- Abundance of centrally located nuclei involving
majority of muscle fibres (mostly in type1 fibres)

56. •Atrophy of type 1
fibres, hypertrophy of
type 2 fibres

57. • Are the muscle fibres abnormal??
• Is the pathologic process-
neurogenic/myopathic??
• What is the distribution of pathology??
• Are there any diagnostic features??

58.  If abnormal??
 Size-small or large
 Shape-rounded or angular
 Type-grouping, fiber predominance
 Internal architecture-disordered/lost, vacuoles,Internal nuclei, inclusions
 Storage/acumulated material-glycogen, lipid, mitochondria
 NEUROGENIC/MYOGENIC
• Shape of muscle fibers –
• ROUND Myopathic
• ANGULAR Neurogenic

59.  ACUTE OR CHRONIC
 Acute:
 Myopathy-Muscle fiber regeneration
 Neuropathy-Small angular muscle fibers
 Chronic:
 Myopathy-increased endomysial connective tissue, muscle fiber atrophy &
hypertrophy
 Neuropathy-fiber type grouping ,pyknotic nuclear clumps

60.  UNIFORM- Dystrophy,
 REGIONAL - --
Neuropathy -Progressive denervation with reinnervation
Myopathy- Myopathic grouping, perifascicular atrophy
Inflammatory myopathies -Patchy fascicular changes,
focal denervation of Group of muscle fibers
 SCATTERED muscle fibers: Acute myopathy, Acute neuropathy

61.  In patients with suspected myopathy, needle EMG should be
performed on muscles on only one side of the body; a
subsequent muscle biopsy should be performed on the other
side.

63.  Bradley’s Neurology in Clinical Practice, 7th edition, 1915-19
 C. Sundaram and Megha S. Uppin (2012). Approach to the
Interpretation of Muscle Biopsy, Muscle Biopsy, Dr. Challa
Sundaram (Ed.), ISBN: 978-953-307-778-9
 Emedicine, medscape