KEY FACTS Terminology Tarsal tunnel syndrome Imaging Denervation of affected plantar intrinsic muscles Uniform high signal intensity on fluid-sensitive sequences Mass in tarsal tunnel Ganglion cyst: Follows fluid signal intensity, homogeneous, ± thin rim of enhancement with gadolinium Nerve sheath tumor: Round or ovoid shape, often shows “tail” where it arises from nerve, diffuse enhancement Venous varicosities: Serpentine, enlarged vessels in tarsal tunnel, can be followed…

KEY FACTS Terminology Synonyms: Common peroneal nerve (CPN) palsy, CPN entrapment CPN entrapment at fibular head Imaging CPN swelling, abnormal T2 hyperintensity Fascicular architecture preserved in milder cases (neuropraxic injury) Loss of internal fascicular architecture in more severe cases (axonotmetic, neurotmetic) Top Differential Diagnoses Ganglion cyst Viral neuritis Nerve sheath tumor Direct acute CPN trauma Pathology Usual etiology is entrapment or sequelae of continued pressure on…

KEY FACTS Terminology Pronator syndrome: Nerve entrapment at pronator teres Carpal tunnel syndrome: Nerve entrapment at carpal tunnel Imaging Nerve enlargement distal to region of entrapment Fascicles indistinct Perineural enhancement ± mass compressing nerve Denervation changes in muscles distal to entrapment Top Differential Diagnoses Cervical radiculopathy Tenosynovitis Peripheral nerve sheath tumor Thoracic outlet syndrome Pathology Common etiologies Overuse, arthritis, anatomic variants Fractures Less common = neoplasm…

KEY FACTS Terminology Suprascapular nerve impingement with muscle denervation Imaging Suprascapular nerve impingement may occur at either spinoglenoid or suprascapular notch Spinoglenoid notch: Between neck and blade of scapula, roofed by spinoglenoid ligament Entrapment affects infraspinatus muscles only Suprascapular notch: At superior border of scapula, roofed by superior transverse ligament Entrapment affects both supraspinatus and infraspinatus muscles Denervation edema is 1st sign on MR Uniformly increased…

KEY FACTS Terminology Synonyms: Ulnar nerve (UN) entrapment, cubital tunnel syndrome Partial fixation, compression, or distortion of UN Imaging UN enlargement ± abnormal T2 hyperintensity, architectural distortion Most commonly occurs within cubital tunnel (elbow); uncommon at Guyon tunnel (wrist) or brachial plexus Top Differential Diagnoses Acute direct nerve trauma Idiopathic brachial plexitis (Parsonage-Turner syndrome) Nerve sheath tumor Enlarged perineural vein Medial epicondylitis Pathology Edematous/indurated UN ±…

KEY FACTS Terminology Synonyms: Femoral neuropathy, femoral mononeuropathy, femoral nerve (FN) palsy FN entrapment or injury secondary to direct trauma, compression, stretch injury, or ischemia Imaging Nerve enlargement ± loss of internal fascicular architecture, ↑ T2 hyperintensity Injury most common in psoas muscle body, iliopsoas groove, or femoral canal Top Differential Diagnoses Neoplastic femoral nerve infiltration Nerve sheath tumor Lumbosacral disc syndromes Lumbar plexopathy Pathology Reported…

KEY FACTS Terminology Group of inherited disorders characterized by focal or diffuse peripheral nerve enlargement Hereditary motor-sensory neuropathy (HMSN), hypertrophic neuropathy (HN), hereditary sensory neuropathy (HSN), hereditary motor neuropathy (HMN), hereditary sensory and autonomic neuropathy (HSAN), Charcot-Marie-Tooth (CMT) syndrome Imaging Focal or diffuse fusiform peripheral nerve enlargement Peripheral nerves ± intradural nerve roots ± involvement of cauda equina nerve roots Acute &/or chronic muscle denervation changes…

KEY FACTS Terminology Parsonage-Turner syndrome Imaging Can affect any muscle innervated by brachial plexus Most common: Rotator cuff, deltoid, biceps, triceps Denervation edema is earliest finding Diffuse, homogeneous high signal on T2WI, STIR throughout affected muscle – Often, muscles innervated by 2 or more different peripheral nerves are affected ± T2/STIR hyperintensity of plexus Fatty atrophy occurs in chronic denervation (uncommon) Top Differential Diagnoses Cervical radiculopathy…

KEY FACTS Terminology Synonyms: Brachial plexus stretch injury, brachial plexus avulsion, avulsion pseudomeningocele Stretch injury or avulsion of ≥ 1 cervical roots, brachial plexus Imaging Stretch injury: Enlargement, abnormal edema of neural elements Avulsion: Abnormal cerebrospinal fluid signal intensity within empty thecal diverticulum Top Differential Diagnoses Nerve sheath tumor Lateral meningocele Nerve root sleeve cyst Chronic inflammatory demyelinating polyneuropathy (CIDP); less often acute inflammatory demyelinating polyneuropathy…

KEY FACTS Terminology Secondary muscle injury resulting from denervation following nerve injury Imaging Acute denervation Muscle appears normal on T1WI Diffusely increased signal intensity on T2WI, STIR Mild, homogeneous enhancement with gadolinium Chronic denervation Fatty atrophy evident on T1WI Muscle volume decreased Denervation edema often persists for prolonged period Top Differential Diagnoses Disuse atrophy Muscle trauma Muscle inflammation or infection Radiation myopathy Pathology Nerve tumor, infection,…

KEY FACTS Terminology Thoracic outlet syndrome (TOS) Neural, venous, &/or arterial compressive syndrome at thoracic outlet (TO) Diagnosis made by 1 of 3 methods (by event, affected structure, or compression cause) Imaging ± cervical rib, elongated C7 transverse process ± brachial plexus compression or distortion, scalene muscle inflammation or fibrosis, abnormal vascular flow voids within TO Positional occlusion or narrowing of subclavian artery (SCA) with arm…

KEY FACTS Terminology Synonym: Pancoast tumor Benign or malignant neoplasm extending to superior thoracic inlet with severe shoulder/arm pain along C8, T1, T2 nerve trunks, Horner syndrome, weakness + atrophy of intrinsic hand muscles (Pancoast syndrome) Imaging Soft tissue apical lung mass with variable extension into chest wall, adjacent bone destruction, brachial plexus invasion Top Differential Diagnoses Metastatic disease Other thoracic tumors [besides nonsmall cell lung…

Terminology Nerve rootlets : Individual neural filaments of dorsal and ventral roots directly exiting from spinal cord Nerve roots : Composed of multiple individual dorsal or ventral nerve rootlets Dorsal sensory roots exit from dorsolateral cord and have cell bodies within dorsal root ganglion (DRG). Ventral motor roots arise from anterior cord gray matter and have cell bodies within the cord. Dorsal root ganglion (DRG) :…

KEY FACTS Terminology Skeletal disorder characterized by low bone strength and increased risk of fracture Imaging Bone scintigraphy and MR are most sensitive to detect osteoporotic spine and sacral insufficiency fractures Bone mineral density Standard measure for diagnosis of osteoporosis (OP) and assessment of fracture risk WHO T-score cut-off value for OP: -2.5 Thinning of cortex on radiographs and CT Normal or heterogeneous signal intensity (SI)…

KEY FACTS Terminology Spinal cord ischemia/infarction Secondary to vessel occlusion Anterior spinal artery (ASA); T4-9 most vulnerable Posterior spinal artery (PSA) Hypotensive (cord “watershed” zone = central gray matter) Imaging MR with contrast, + diffusion Cord hyperintensity on T2WI; central owl's-eye pattern Central gray matter or entire cross-sectional area Slight cord expansion in acute phase Top Differential Diagnoses Multiple sclerosis Transverse myelitis Acute disseminated encephalomyelitis/viral myelitis…

KEY FACTS Terminology Synonyms: Type 1 spinal arteriovenous fistula (AVF), dural AVF, dural fistula Definition: Spinal AVF, present within dura, with intradural distended draining veins Imaging Cord enlarged, T2WI hyperintense, vessel flow voids on cord surface Multiple enhancing serpentine veins on cord surface Dynamic contrast-enhanced MRA capable of defining dilated intradural veins; very useful to guide catheter angiography Spinal catheter arteriography is gold standard for confirming…

Terminology Synonyms : Great anterior radicular artery, arteria radicularis magna = artery of Adamkiewicz radicularis magna = artery of Adamkiewicz Imaging Anatomy You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

KEY FACTS Terminology Idiopathic hypertrophic pachymeningitis IgG4-related hypertrophic pachymeningitis Multiorgan immune-mediated condition, which mimics multiple malignant, infectious, and inflammatory disorders Chronic progressive diffuse inflammatory fibrosis of dura of brain or spine Imaging Linear low signal mass involving dura with variable mass effect upon cord Low signal linear mass effacing cerebrospinal fluid (CSF) and cord Peripheral enhancement related to peripheral zone of active inflammation vs. chronic central…

KEY FACTS Terminology Red marrow: Hematopoietic marrow Yellow marrow: Fatty marrow Imaging Yellow marrow often distributed around central perforating vein Yellow marrow adjacent to endplates in degenerative disc disease After bone marrow transplantation: Fat centrally located in vertebral body, red marrow at periphery Yellow marrow high T1W signal intensity Red marrow low to intermediate T1W signal intensity Signal intensity equal or slightly higher than muscle Top…