An Algorithmic Approach to MR Imaging of Hypomyelinating Leukodystrophies.

Hypomyelinating leukodystrophies (HLDs) are a heterogeneous group of white matter diseases characterized by permanent deficiency of myelin deposition in brain. MRI is instrumental in the diagnosis and recommending genetic analysis, and is especially useful as many patients have a considerable clinical overlap, with the primary presenting complains being global developmental delay with psychomotor regression. Hypomyelination is defined as deficient myelination on two successive MR scans, taken at least 6 months apart, one of which should have been obtained after 1 year of age. Due to subtle differences in MRI features, the need for a systematic imaging approach to diagnose and classify hypomyelinating disorders is reiterated. The presented article provides an explicit review of imaging features of a myriad of primary and secondary HLDs, using state of the art genetically proven MR cases. A systematic pattern-based approach using MR features and specific clinical clues is illustrated for a quick yet optimal diagnosis of common as well as rare hypomyelinating disorders. The major MR features helping to narrow the differential diagnosis include extent of involvement like diffuse or patchy hypomyelination with selective involvement or sparing of certain white matter structures like optic radiations, median lemniscus, posterior limb of internal capsule and periventricular white matter; cerebellar atrophy; brainstem, corpus callosal or basal ganglia involvement; T2 hypointense signal of the thalami; and presence of calcifications. The authors also discuss the genetic and pathophysiologic basis of HLDs and recent methods to quantify myelin in vivo using advanced neuroradiology tools. The proposed algorithmic approach provides an improved understanding of these rare yet important disorders, enhancing diagnostic precision and improving patient outcomes. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 5.

Dextromethorphan Associated Neurotoxicity with Cerebellar Edema (DANCE) Syndrome in Young Children: Neuroimaging Features.

Dextromethorphan toxicity in young children (especially those with age 4 years or younger) can have an extremely poor prognosis if untreated. However, if timely recognized and optimally managed, it can have a good clinical outcome despite significant initial insult. We present 3 pediatric cases (< 5 years old) with sudden unresponsiveness following ingestion of cough medications containing dextromethorphan. All these children showed cytotoxic edema in cerebellar hemispheres on MR brain, with diffusion restricting foci in supratentorial white matter in 2 patients. These features resemble the recently described acute opioid toxidrome in children, the POUNCE syndrome (Pediatric Opioid Use-associated Neurotoxicity with Cerebellar Edema). Hence, we name this entity "DANCE" (Dextromethorphan Associated Neurotoxicity with Cerebellar Edema) to increase the awareness of dextromethorphan toxicity in young children and the need to promptly recognize it to initiate optimal management.ABBREVIATIONS: POUNCE= Pediatric Opioid Use-associated Neurotoxicity with Cerebellar Edema; DANCE= Dextromethorphan Associated Neurotoxicity with Cerebellar Edema.

Medial Pterygoid Abscess Masquerading as a Temporomandibular Joint Disorder: A Case Report.

A patient presenting with a history of restricted mouth opening and deflection of the mandible after a prolonged dental procedure raises a suspicion of temporomandibular joint disorder (TMD) due to its estimated high prevalence of 29%. Muscle relaxants and routine active physiotherapy established normal range of movement and pain reduction was achieved through TENS therapy and analgesics. However, the non-subsidence of deflection prompted an initial suspicion of TMD which was overturned by MRI. The MRI evaluation revealed left side medial pterygoid abscess. It is imperative to understand that despite strong history and relevant clinical features, for the definitive diagnosis radiographic evaluation is highly contributory. Misdiagnosing TMD due to its similar presentation can have significant implications for the patient's well-being and quality of life. The clinical features of medial pterygoid abscess including restricted mouth opening and pain can be similar to that of TMD. These abscesses are most commonly caused by odontogenic infections but can also occur as a result of septic inferior alveolar nerve block techniques. Limited literature reports of pterygoid space abscess have been described, but intramuscular and medial pterygoid abscess is an absolute rarity. Causal relationship to septic inferior alveolar nerve block further makes this case report an interesting read.

Endovascular and percutaneous embolization of a giant post traumatic arteriovenous fistula of inferior epigastric vessels.

BACKGROUND: Arteriovenous fistulas involving the anterior abdominal wall can result from trauma. Such fistulas may remain asymptomatic and undetected for a prolonged duration of time. They tend to recruit multiple arterial feeders with remodelling in the feeding arteries, making them challenging to treat. CASE PRESENTATION: We discuss a rare case of a 60-year-old male who presented with complaints of a progressive painless swelling in right lower abdomen. There was a history of blunt injury to abdomen at the same site during alleged road traffic accident 3 years ago. On CT angiography, an arteriovenous fistula was localised to the anterior abdominal wall arising predominantly from the right inferior epigastric artery with a giant venous sac and terminating as a tortuous single venous channel into the right external iliac vein. Few other small feeders were also seen arising from branches of right superior epigastric artery along Winslow's pathway. The main challenge in endovascular management of this patient was embolization of a high flow shunt with a large venous sac and multiple arterial feeders. The dominant arterial feeder was embolized using vascular plug. The superficial location of the lesion offered an additional percutaneous window besides endovascular approach. The venous sac was percutaneously accessed and embolized using n-butyl cyanoacrylate after balloon occlusion of outflow vein. On follow up ultrasonographic evaluation at 3 months, near complete thrombosis of the venous sac was achieved. CONCLUSIONS: Traumatic arteriovenous fistulas involving the inferior epigastric vessels are rare clinical entities. CT angiogram and digital subtraction angiography help in the optimal diagnosis and treatment planning. The use of mechanical embolization devices to cause flow arrest offers an opportunity to use liquid embolic agents which offer better percolation within the lesion. Interventional radiology offers an ideal management of these complex high flow fistulas with a good technical success and acceptable safety profile.