Saturday, 7 September 2019

Ataxia Telangiectasia MRI


MRI brain shows:
1. Moderate grade diffuse cerebellar atrophy. No associated Brainstem or cerebral cortical atrophy.
2. Multiple punctate low signal intensity foci on GRE in bilateral cerebral white matter.

Imaging diagnosis: Ataxia-telangiectasia.

Ataxia Telangiectasia 

A rare multisystem condition with autosomal recessive inheritance, incidence at around 1:40,000-300,000 live births, sometimes classified as a phakomatosis.
Characterized by multiple telangiectasias, cerebellar ataxia, pulmonary infections and immunodeficiency.

Diagnostic clue on MRI brain is diffuse cerebellar atrophy, compensatory enlargement of the fourth ventricle, micro hemorrhages secondary to capillary telangiectasia.
Main clinical features include cerebellar ataxia progressive and present in all cases, associated oculomucocutaneous telangiectasias, susceptibility to pulmonary infection due to immunodeficiency.
Genetics, results from a defective gene located on chromosome 11q22–23.
Treatment is generally supportive.

Cysts in gyrus rectus of frontal lobe

Clinical Details  : 42 yo female, sometime in May 2019 suffered from an episode of un responsivity associated with no features to suggest a seizure. There was no excessive perspiration. She however regains consciousness spontaneously after about 15 minutes. Thereafter she was well but on the 9th of August abruptly lost consciousness, had abnormal tonic posturing of the limbs, hyper salivation but no tongue bite or incontinence. SHe however had excessive profuse perspiration. 

Present clinical examination is entirely normal. 
BP 130/90

MR study of brain reveals multicystic changes clustered in the gyrus rectus of right frontal lobe.
Clinical significance is doubtful in this case.
However this is a rare finding so far reported only with tourette syndrome in literature.

Ref :
Tourette syndrome associated with unilateral cystic changes in the gyrus rectus.
McAbee GN1, Wark JE, Manning A Department of Pediatrics (Neurology), University of Medicine and Dentistry of New Jersey, Children's Regional Hospital at Cooper Hospital/University Medical Center, Camden 08103, USA.

Sunday, 1 September 2019

Tumor Mimics MRI

FLAIR
T2W
DWI
T2*GRE
T1


MR SPECTROSCOPY
PERFUSION IMAGING

This MRI study of brain shows an intra axial space-occupying lesion measuring approximately 53x55mm involving left opercular parietal and adjacent insular cortex with marked focal parenchymal swelling, lesion non-enhancing on post contrast. No mid line shift or mid brain compression. No obvious cystic or necrotic component. No diffusion restriction or haemosiderin staining on GRE.

ASL 
3D arterial spin labelling (non-contrast perfusion) was performed. Cerebral blood flow (CBF) assessed in ml /100 gm / min

Findings: 
The lesion predominantly shows mixed perfusion, major portion show hypo perfusion with patchy areas of relative hyper perfusion with CBF in range of 11 ml / 100 gm / min , 160% of reference in its cranial aspect. 

PERFUSION IMAGING
Perfusion maps demonstrated with color scale used are as follows. 
CBF: cerebral blood flow; higher scale (red) means faster flow and lower scale (blue) mean less flow.
CBV: cerebral blood volume ; higher scale (red) means more volume and lower scale less volume.
MTT: mean transit time; higher scale (red) means longer time required to washout contrast and lower scale (blue) means short time early washout.
TTP: time to peak; higher scale (red) means longer TTP and lower scale (blue) means shorter TTP.

Findings:
Lesion is relatively hyper perfused. 
rCBF:          11  ml/100gm/ min   160% of reference
rCBV:        3.2   ml / 100gm tissue 482% of reference
MTT:        17; 296% of reference   

Interpretation:

Lesion show mixed perfusion, areas of hypo - iso perfusion, a focal hyper perfusion particularly left parietal sub cortical portion of lesion. 

MR SPECTROSCOPY 

Axial T2w localizer taken and multi voxel MR Spectroscopy performed. The voxel of size 2x2cm placed over the lesion. Water suppression obtained was 99% with optimum spectral waveform obtained at short as well as long TE.

Metabolites evaluated on short TE of  35ms and TR of 1500ms from right to left as follow. 
At 2.01ppm – short and wide peak of NAA. NAA is reduced.
At 3.03ppm – sharp and long peak of Creatinine. Creatinine is reduced.
At 3.2ppm – sharp and long peak of Choline. High choline.
No lipid lactate.

NAA/ Creatinine ratio is 2
Choline/ Creatinine ratio is 1.5

Interpretation: 

Lesion show high choline, reduced Creatinine. 

Summary: 

This MRI study of brain shows an intra axial lesion involving left opercular parietal and adjacent insular cortex with marked focal parenchymal swelling, sub cortical white matter oedema, non-enhancing on post contrast. No obvious cystic or necrotic component. 
No diffusion restriction or haemosiderin staining on GRE.
Lesion show high choline, reduced Creatinine on MR spectroscopy. 
Left parietal sub cortical portion of lesion is hyper perfused on ASL as well as perfusion imaging.

Imagingwise diagnosis: Glioma like Astrocytoma_ Low to Intermediate grade tumour.
But Histopathology report surprise to me.

HISTOPATHOLOGY REPORT : FOCAL CORTICAL DYSPLASIA TYPE III

Microscopic Description : 

The entirely submitted material shows surrounding odematous glial tissue. Punctate haemorrhages, fine micro cystic change, neuronal crowding, Cytomegaly neurons, Peri vascular cuffing and haemorrhages, Occasional Balloon cells. There is no granuloma. 
IHC : Ki 67 index less than 1 %

Post traumatic Neuroma MRI

A 35 old male fell from 8 feet and experienced immediate spine and both hip pain with progressively worsening back pain that radiated to right hip and right lower extremity. Sharp pain radiated from back to toes, and experienced paresthesias from right knee to toes.
On examination, antalgic gait and unable to walk, weakness of right hip flexion, knee extension, ankle dorsiflexion and ankle plantar flexion. A straight leg raise test result was positive on the right at 15°, which indicated neuronal irritation, and was negative on the left leg.
MRI WHOLE SPINE show multiple level benign post-traumatic sub chondral collapses with marrow oedema. No obvious listhesis.
Study extended with MR Neurography of lumbosacral plexus shows a well-defined ovoid mixed but near cystic signal intensity lesion on right side of spine at lumbosacral junction deep to the right psoas muscle. Lesion is ovoid has typical teardrop shape with proximal portion tapering towards neural foramina suggestive of neural/perineural origin of lesion.
Considering history of trauma possibility of post-traumatic neuroma was suggested.

Histopathology examination : Neuroma.
Microscopy shows a disorganized fibroneural tissue contained randomly oriented nerve twigs surrounded by attenuated connective tissue and different types of cells like Schwann cells, macrophages, and fibroblasts, which may extend into adjacent adipose tissue.

Final diagnosis: Post traumatic Neuroma.

Post traumatic Neuromas (PTNs) of Lumbar Plexus

PTNs may be terminal occuring in amputation stumps or when the nerve is completely transected, or they may be in-continuity. Neuromas-in-continuity comprise most nerve injuries from laceration, contusion, or stretch injury.

A peripheral nerve MR Neurography an useful technique for the preoperative diagnosis, localization, and characterization of nerve abnormalities, including PTN formation.

Neuromas present as a fusiform mass with nerve continuity, may be similar in appearance to that of neurogenic tumors, such as schwannomas and neurofibromas. Neuromas unlike neurogenic tumors may not show enhancement. Unlike neurogenic tumors, neuromas-in-continuity lack a split fat sign, which represents a rim of fat that surrounds the tumor, particularly in relation to the proximal and distal portion of the nerve best appreciated on T1-weighted images. Neuromas-in-continuity also lack a target sign, which consists of high signal intensity in the periphery and low signal intensity in the central region of the lesion on T2-weighted images. PTNs of the peripheral nerves have been reported and tend to be low to isointense on T1-weighted imaging and hyperintense on T2-weighted imaging.

Lumbosacral PTN is relatively rare. Radiologists should be aware of the imaging appearance of injury-related neuromas for appropriate diagnosis and avoid misinterpretation as true neoplasms. 

Posterior Epidural Fibrosis Arachnoiditis MRI


MRI LUMBAR SPINE WITH CONTRAST

Changes of lumbar spondylosis. Evidence of laminectomy at L4 - L5, mild disc bulge.
Diffuse homogeneously enhancing posterior epidural T2 hypo intense soft tissue at laminectomy site, clumping of nerve roots appears adherent to dura at laminectomy level. Available anteroposterior bony canal diameter is approximately 14 mm. L5 sacralisation.

Possibility of posterior epidural fibrosis with an associated arachnoiditis suggested for further clinical evaluation.

Sjogren's syndrome MRI Brain


Clinically 40 yo female, a known case of Sjogren's syndrome without any neurological or psychiatric complaints.
Stable well oriented with no signs on neurological examination.

MRI brain shows confluent T2 hyperintensity in bilateral cerebral white matter, corona radiata, external capsules, bilateral dentate nuclei.
No associated cerebral cortical atrophy.
Imaging finding can be labelled as severe changes of small vessel disease, significant for age.

Sjögren syndrome and MRI brain

Sjögren syndrome is a chronic systemic autoimmune disease affecting 2–3% of adults.
Classified as primary when occurring in isolation and as secondary when associated with another autoimmune disease.
Characterized by mononuclear infiltration and destruction of the exocrine glands, mainly the lachrymal and salivary glands, resulting in xerophthalmia and xerostomia.
Apart from the glandular features, mononuclear infiltration of visceral organs and vasculitis can give rise to extraglandular manifestations like arthralgia, pulmonary involvement, renal tubular acidosis.
Neurologic involvement in primary Sjögren syndrome particularly peripheral nervous system involvement is a well-documented feature of the syndrome in about 20–25% that commonly manifests as peripheral sensory neuropathy or mononeuritis multiplex caused by small-vessel vasculitis.

MRI brain of patients with primary Sjögren syndrome has shown multiple areas of increased signal intensity in the periventricular and subcortical white matter on FLAIR and T2-weighted images.
Important to note is this have been observed in both patients with and without CNS impairment or symptoms as in our case. Brain atrophy has been reported in a limited number of studies of patients with primary Sjögren syndrome.

Reference : https://www.ajronline.org/doi/10.2214/AJR.10.5984. 

Spinal Arachnoid Cyst MRI

MRI dorsal region shows an intra dural extramedullary well-defined lentiform shaped arachnoid cyst measuring approximately 22x8mm at D3-4 severely compressing cord from posteriorly with cord flattening.

Operated with posterior laminectomy.
Histo pathology report : Arachnoid cyst. 

Spondylodiscitis MRI

Description of findings:

At D11-12 discal and paradiscal involvement. Diffuse altered marrow signals involving vertebral bodies; diffuse low marrow signals on T1w, intermediate signals on T2w. Diffuse high signal intensity on STIR implies to marrow edema. Posterior elements are uninvolved.
Intervening intervertebral disc and end plates are destroyed with endplate erosions, reduced height of vertebral bodies due to sub chondral collapse, exaggerated anterior curvature at this level due to anterior wedging with prominent posterior corners contributing to severe canal stenosis, severe cord compression, cord oedema, bilateral neural foraminal stenosis with exiting nerve root compression in neural foramina. An associated prevertebral, anterior epidural abscess.

Impression:

At D11-12 Spondylo Discitis with pre vertebral and anterior epidural abscess, severe cord compression, cord oedema.

Sunday, 18 August 2019

Sickle Cell Anemia MRI


MRI SCREENING OF WHOLE SPINE, SI AND HIP JOINT
Multiple vertebrae show subchondral collapse in dorso lumbar region.
Hip screening show avascular necrosis involving bilateral capital femoral epiphysis..
Ill-defined heterogeneous marrow oedema involving Acetabular fossa, Femoral head neck on either side, mild joint effusion.

Suggested detailed haematological / bone marrow evaluation.
Further evaluation turned out sickle cell anaemia.

Sickle cell disease

A hereditary autosomal recessive condition resulting in the formation of abnormal hemoglobin which manifests as multisystem ischemia and infarction as well as hemolytic anemia. 
There is no gender predilection. 
Highest incidence occurs in individuals of African descent, followed by eastern Mediterranean and Middle Eastern populations. 
The sickle cell mutation is prevalent in part as it confers a human genetic resistance to malaria as the abnormal hemoglobin has higher turnover and increased phagocytosis while sickled red cells have reduced cell-cell cytoadherence preventing the parasite from multiplying during the erythrocytic phase of its life cycle. It is estimated that approximately 8% of the African population is homozygous for sickle cell where malaria is most prevalent.
The earliest manifestation is usually in early childhood, as babies are protected by elevated levels of fetal hemoglobin (HbF) in the first 6 months3. 
Commonly a painful vaso-occlusive crisis, sudden onset of bone or visceral pain due to microvascular occlusion and ischemia.
Three separate mechanisms can result in skeletal changes: 
1. chronic anemia resulting in expansion of the medullary spaces
2. vaso-occlusive crises resulting in bone infarcts and subperiosteal hemorrhages

3. infection, osteomyelitis.

MPS MRI

MRI study of brain reveals:
Diffuse cerebral cortical atrophy.
Enlarged Peri vascular spaces involving bilateral Cingulate gyri, corpus callosum.
Diffuse thickening of bony calvarium.
J shaped Sella.

MRI study of Spine reveals:
Bullet-shaped vertebra at multiple levels.
Dorsal dermal sinus in sacral region extending towards S4 without fusion or segmentation anomaly. No obvious cord tethering.
Spleen 10 cm, moderate splenomegaly.
Liver 12 cmM mild to moderate hepatomegaly.

Possibility of Mucopolysaccharidosis suggested for further clinical evaluation.

Ewing's Sarcoma MRI Spine

A young male with progressive paraplegia.
MRI DORSAL SPINE shows:
A lentiform shaped well defined posterior epidural soft tissue in mid dorsal region with marked homogeneous enhancement on post contrast causing severe cord compression, abnormal intra medullary signals in compressed cord. There is an associated altered marrow signal, marrow oedema involving neural arch of adjacent vertebra with mild expansion of spinous process of corresponding vertebra.

Imaging wise differential  diagnosis considering young age of patient:
Ewing sarcoma, osteosarcoma, round cell tumour, aggressive haemangioma, Haemangiopericytoma.

Operated with posterior Decompressive laminectomy, excision of tumour.

Histopathology Report : Ewing Sarcoma.

Crossed Cerebellar Diaschisis CT Brain


For similar case Click here

Crossed cerebellar diaschisis

Refers to a depression in function, metabolism and perfusion affecting the cerebellar hemisphere as a result of contralateral supratentorial lesion.
This disturbance occures in a portion of the brain at a distance from the original site of injury but connected via white matter tracts.
Initially this phenomenon was defined as being caused by an acute lesion but now considered being related to a lesion of any temporal duration.
Other than neurological deficits and clinical features associated with the contralateral supratentorial lesion, this condition is generally asymptomatic.
This is a well-recognised phenomenon following cerebral infarction, although it can be a sequela of any significant supratentorial lesion like tumours, intracerebral haemorrhage, encephalitis , Dyke-Davidoff-Masson syndrome, Radiation necrosis etc.
There is no treatment for this phenomenon other than management of the supratentorial insult and prevention of further insults.

Brachial plexitis MRI

MR Neurography of Brachial Plexus
Clinically :  middle-aged male with left arm pain and weakness of sudden onset. No history of trauma. No history of radiotherapy.

MR Neurography of brachial plexus show diffuse enlargement with abnormal T2 hyperintensity iinvolving left brachial plexus nerves. Mild enlarged bilateral deep cervical group of lymph nodes.

Imaging diagnosis: Left side brachial plexitis.

Brachial plexitis

An inflammatory change involving the brachial plexus commonly seen in men between 30 to 70 years of age and is bilateral in 10-30% of patients .

Etiology:
post radiation plexitis: usually presents 5-30 months after treatment.
viral brachial plexitis, e.g. cytomegalovirus, Coxsackie, herpes zoster, Epstein-Barr virus, parvovirus B19
immune-mediated
toxic (related to previous serum, vaccine, antibiotic or other drug administration, human immunodeficiency virus serology)
recent surgery
anesthesia
Lyme disease
heredofamilial hypertrophic neuropathies like Charcot-Marie-Tooth disease, Dejerine-Sottas disease, chronic inflammatory demyelinating polyneuropathy.
idiopathic ; Parsonage-Turner syndrome.

Diagnostic clues on MR Neurography are diffuse enlargement of nerves of brachial plexus with abnormal T2 hyperintensity and enhancement on post contrast MRI.

Amyotrophic Lateral Sclerosis MRI

Clinical Details  : 45 yo male, from last five months has been having slowly progressive right distal arm, hand and recently right leg weakness which seems to be progressive. There is no sensory symptoms. No bowel bladder disturbance. Recently has also noted some slurrring of speech and tremulousness of both hands. Clinical examination shows poly myoclonus. Hyper reflexia, right plantar is extensor. Mild right facial weakness, eye movements are normal. Sensations are normal.

Clinically suspected Amyotrophic Lateral Sclerosis.
MRI Findings:
Contiguous bilateral symmetric T2 hyperintensity along posterior limb of internal capsule, extending in adjacent Corona radiata and along cortical spinal tract portion of Brainstem.
MRI DWI images normal.
Normal MR Angiography of Brain.
Finding consistent with clinical diagnosis of Amyotrophic Lateral Sclerosis.

Amyotrophic Lateral Sclerosis 

Lou Gehring disease, A motor neuron disease.

Can be defined as a selective degeneration of somatic motor neurons of Brainstem, spinal cord that is lower motor neuron, pyramidal neurons of motor cortex that is upper motor neuron and eventual loss of corticospinal tract fibres.

Diagnostic clue on imaging is bilateral symmetric contiguous long segment T2 hyperintensity extending along corticospinal tract from motor cortex at Precentral gyrus through bilateral corona radiata, posterior limb of internal capsule, Brainstem and onwards.

Imaging differential diagnosis is Distal Wallerian degeneration in which signal abnormality is often unilateral, associated with primary lesion like bleed or infarct if bilateral has to be asymmetric.
Other conditions with T2 hyperintense lesion at various levels of corticospinal tract are metabolic like x linked adrenoleukodystrophy, Wilsons disease, hypoglycaemic comma, demylinating and inflammatory diseases like multiple sclerosis, ADEM, Behcets disease.

Please make one important note that corticospinal tract can appear hyperintense on 3 Tesla MRI due to Fractional anisotrophy related artefacts in a normal fully demylinating brain at any age and mimic Amyotrophic lateral sclerosis. So clinical back up is important before giving the diagnosis solely based on imaging.

Majority of cases are sporadic but in 15 to 20% of cases they are familial. Common in 4th to 7th decade of life. Twice common in males.
Clinically upper motor signs like Babinski sign, spasticity, hyperreflexia andd lower motor neuron signs like asymmetric muscle weakness, atrophy, fasciculation, Hyporeflexia should be looked for. 

Wednesday, 3 April 2019

Nothnagel syndrome MRI

A rare midbrain stroke syndrome that involves the tectum of the midbrain, including the quadrigeminal plate.
Classically, the syndrome involves the oculomotor nerve fascicles and superior cerebellar peduncle, leading to ipsilateral CN III palsy and limb ataxia respectively.
Although it can be caused by stroke, especially hemorrhages rather than infarctions, it is more commonly seen due to neoplasm.

Tuesday, 12 March 2019

Nasolabial cyst MRI


Nasolabial cyst also known as nasoalveolar cyst or Klestadt Cyst.
A rare non odontogenic, developmental cyst derived from epithelial cells retained in mesenchyme after fusion of medial and lateral nasal processes and the maxillary prominence during fetal development, occurring in midline at superior alveolar margin in alar region of nose.
3 times more common in females than males, most often an asymptomatic, mobile fluctuant non-tender swelling.
Often detected incidentally on CT or MRI BRAIN as isodense round nodule on CT. Signal characteristic of lesion varies on MRI ranges from hypo-to hyperintense on T1-weighted images and Hyperintense to hypointense on T2-weighted images depending upon its content, clear or thick.
Differential diagnosis is odontogenic cyst which is peri apical inflammatory lesion associated with osseous thinning of adjacent superior articular margin. 

Wednesday, 6 February 2019

Fukuyama congenital muscular dystrophy MRI

Clinically: Floppy infant / hypotonia.


MRI findings:
Bilateral frontal Polymicrogyria.
Diffuse cerebral cortical atrophy marked in bilateral frontal and temporal lobes.
Bilateral temporo occipital white matter show patchy T2 hyper intensity suggestive of associated dysmyelination, bilateral hippocampal Mal orientation, ex vacuo dilatation of temporal horns of lateral ventricles.
Associated hypoplasia of corpus callosum.
Poorly pneumatised of paranasal sinuses and mastoid air cells.
Micro crania, brachycephaly, small posterior fossa.
Brainstem atrophy, mid line cleft on ventral aspect of Pons.
No associated cerebellar dysplasia. Ill-defined mid line vermis.

Impression:

Imaging diagnosis: Fukuyama congenital muscular dystrophy more likely than Walker Warburg syndrome as there is no associated cerebellar dysplasia.

Fukuyama congenital muscular dystrophy

Named after Yukio Fukuyama (1928-2014), a Japanese pediatric neurologist, who first described the condition in his 1960.

Exclusively found in Japan with an incidence of 2/4 per 100,000 infants and is the second most common muscular dystrophy after Duchenne muscular dystrophy.
Affected infants are hypotonic, generalised symmetric weakness affecting extremities and facial muscles by 1 year.
Accompanied by developmental delay and intellectual disability afterwards with epilepsy.

An autosomal recessive inherited disease due to a mutation in the fukutin-related protein (FKTN) gene.

Classic MRI brain features are polymicrogyria typically in the frontal and parietal lobes.Pachygyria in approximately half of patients, typically involving the temporal and occipital lobes.
Cerebellar polymicrogyria is seen in approximately 90% of patients. White matter changes patchy, spotty suggestive of dysmyelination.
Walker-Warburg syndrome is one of its main differentials, in which cerebellar dysplasia is commonly seen is not very common in Fukuyama congenital muscular dystrophy

Definitive treatment not available.

Monday, 4 February 2019

Crossed cerebellar diaschisis

Clinical presentation: Frequent seizures, altered sensorium. 


MRI brain shows marked left hemi Atrophy, ex vacuo dilatation of left lateral ventricle owing to volume loss. Left cerebral hemisphere show multifocal patchy areas of cortical T2 hyper intensities without diffusion restriction. Associated Atrophy of left deep grey nuclei, changes of distal Wallerian degeneration involving left cerebral peduncle of mid brain, Pons.

Imaging diagnosis: Sequel of encephalitis / rasmussen encephalitis.

Right cerebellar hemisphere show marked atrophy can attributed to associated contralateral cerebellar diaschisis. 

Crossed cerebellar diaschisis

Refers to supra tentorial lesion leading to depressed function, metabolism and perfusion of contra lateral cerebellar hemisphere which is connected via white matter tracts.
Interruption of this cortico-ponto-cerebellar white matter tracts which then results in deafferentation and hypometabolism of the contralateral cerebellar hemisphere.

Classically seen following cerebral infarction, although it can be a sequel of any significant supratentorial lesion like bleed, encephalitis as in our case. The same phenomenon can also occur in thalamus called ipsilateral thalamic diaschisis, occurring after an ipsilateral middle cerebral artery territory infarction.

CT or MRI perfusion performed during an acute stroke may show a contralateral cerebellar hypo perfusion. In chronic stages volume loss involving contralateral cerebellar hemisphere.

Clinically other than the neurological deficits associated with the contra lateral supra tentorial lesion, the condition is generally asymptomatic. No treatment apart from management of the supratentorial insult.

Sunday, 6 January 2019

Parsonage Turner Syndrome MRI

Clinically : Middle aged male with Left side severe neck and shoulder pain followed by left shoulder abduction weakness.
MRI cervical spine normal.
Neurological examination mentions rotator cuff abductor weakness and latissimus dorsi wasting. 
NCV findings positive, confirmed left side supra scapular neuropathy. 



MRI shows diffuse T2 hyper intense odema involving supra and infra spinatous muscle.
Deltoid muscle spared. No obvious para labral cyst or supra glenoid notch cyst to cause supra scapular nerve compression.
Clinically spontaneous sudden onset without history of trauma or weight lifting.

Clinical history and imaging findings are typical of Parsonage Turner Syndrome.

Parsonage Turner Syndrome 

An acute idiopathic brachial neuritis.
Male predominance,majority between 3rd to 7th decade.
Clinical presentation is typically quite sudden painful shoulder girdle followed by progressive weakness.
Symptoms non-specific and can mimic numerous other much more common conditions.
Condition is unilateral in two-thirds of cases.
A combination of history, EMG with suprascapular neuropathy and imaging findings makes the diagnosis.
The etiology is uncertain, although viral infection or immunological cause is suspected.
In almost all cases (97%) the suprascapular nerve is involved and muscles are supraspinatus and infraspinatus (innervated by suprascapular nerve.
The most striking features on MRI are denervation changes in muscles with diffuse high T2 signal. Gradually atrophy and fatty infiltration on follow up imaging or chronic cases.
Typically self-limiting and requires supportive therapy. 90% will have excellent recovery by three years.