 Hello everyone, today I will be presenting a paper on the cervical spine MRI findings in Hirayama disease under the guidance of Dr. Tushar Kallekar, professor, department of radio diagnosis at Dr. D. Y. Patel Medical College Hospital and Research Center in Pune. The primary aims and objectives of the study were to assess the prevalence and clinical presentations of Hirayama disease in the local population, to assess the imaging findings and to ascertain the most common and objective findings for diagnosis and to classify the various cervical spine MRI findings based on the extent of involvement. Hirayama disease is a rare type of cervical myelopathy caused by trauma from flexion of movements of the neck. It typically occurs in young Asian males in the second or third decade. The underlying etiology is considered to be neck losses of anterior muscles due to chronic micro circulatory changes in the anterior spinal artery territory and used by repeated or sustained neck flexion. It typically presents with unilateral weakness and a mitrophy of the lateral upper limb in the hand and forearm with sparing of the sensory nerves. Occasionally, cause tremors can also be seen. The disease usually progresses for three to five years and then has a stationary phase. On MRI in neutral position, intramedillary high signal intensity on T2 weighted images and subtle asymmetrical lower cervical cord atrophy can be seen. However, MRI with cervical flexion is more sensitive and shows forward displacement of the posterior dura with increased level of neural space and post contrast enhancement of a crescent-shaped posterior dural sac. Prominent epidural flow voids may also be seen on cervical flexion. The place of study was Dr. D. Vipartan Medical College Hospital and Research Center in Pune. It was a retrospective cross-sectional study over a period of six years, starting from January 2017 to December 2022. A total of 13 patients with Hirayama disease were found on a review of the hospital PAC system. Patients of all age groups who had a principal diagnosis of Hirayama disease on MRI were included while patients who had not undergone MRI with cervical flexion or had inconclusive imaging findings for Hirayama disease were excluded. Standard cervical spine protocol was used which included axial, sagittal and coronal T2 weighted images and axial and sagittal T1 weighted images with additional sagittal and axial T2 weighted images taken on cervical flexion. Eight of the 13 patients had undergone a contrast study and post contrast T1 sagittal and T1 axial images were also available. The following results were obtained. The first table shows the sex distribution of the patients. Among the 13 patients studied, almost 92 percent, that is 12 of the 13 patients were male and only a single female patient was studied. The second table shows the age distribution of patients. The majority of the patients were young with nine patients aged between 16 and 25 years of age and only two patients between 26 and 35 years of age. The youngest was a girl of seven years and the oldest was a 75-year-old male. The third table summarizes the presenting clinical symptoms of patients. Upper limb weakness was the most common symptom seen in around 92 percent patients. It was unilateral in seven patients and bilaterally asymmetric in five patients. Upper limb muscle atrophy was the second most common symptom seen in around 54 patients. It was unilateral in four patients and bilateral in three patients. One patient each presented with unilateral and bilateral upper limb tremors, which was a relatively rare symptom. A seven-year-old female child presented with the atypical symptom of bilateral clawing of hands. Table four summarizes the MRI findings seen in patients. All patients showed excessive forward shifting of the posterior dura on flexion with resultant chord compression. One patient showed only mild chord compression without signs of myelopathy. While 12 patients showed cervical chord compression with an abnormal T2 hyperintense chord signal and asymmetric chord atrophy. The levels at which patients showed forward shift of the posterior dura and chord compression have been summarized. All 13 patients showed increased laminodural space on flexion. The maximum laminodural distance that is the anterior posterior distance seen in patients on flexion and the length which is the crinocardial distance of increased laminodural space is also summarized in the fourth table. Prominent epidural flow wires on flexion were also seen in approximately 46 percent patients. All eight patients who underwent the contrast study showed enhancement of the epidural component on flexion. Now moving on to a few images from the patients included in the study. The first set of images shows the type of intramedullary chord hyperintensities. The image A shows subtle T2 intramedullary chord hyperintensity. Image B shows a unilateral hyperintensity whereas image C shows bilateral hyperintensity on T2 weighted axial images. The next set of images shows chord compression and various stages of myromilasia. The first set of images A and D show chord compression without abnormal chord signal intensity. The second set of images B and E show chord compression with abnormal chord intensity. Whereas the last set of images C and F show chord compression with chord atrophy. Image A show the next set of images shows an extent of maximum AP thickness of laminar dural space on flexion. The first image shows mild increase in laminar dural space thickness approximately 0.23 centimeters. The second image shows moderate increase in the laminar dural space approximately 0.41 centimeters. And the third image shows severe increase in the laminar dural space approximately 0.52 centimeters. The next set of images shows the cranial chordal extent of the increased laminar dural space on flexion. The first image shows mild cranial chordal extent. The second shows a moderate cranial chordal extent and the last image shows a severe cranial chordal extent of the increased laminar dural space. The last set of images shows contrast enhancement of the posterior epidural space. In this, the first set of images in the top row show a patient with markedly increased laminar dural space on the flexion T1 sagittal image showing post contrast enhancement on sagittal as well as axial images. The second set of images in the bottom row show contrast enhancement in a case with mild increase in laminar dural space in image D, moderate increase in laminar dural space in image E and severe increase in laminar dural space in image F with post contrast enhancement seen in all these three cases. Hirayama disease was first described by Japanese neurologist Kizohirayama in 1959. The entity is also called juvenile muscular atrophy of the distal upper extremities. Hirayama disease is a male prone condition occurring most commonly between 15 and 25 years of age. It is characterized by unilateral and asymmetric bilateral weakness of the hand and forearm muscles supplied by C7 to T1 myotones and sparing of the brachioridialis muscle. There is no lower limb involvement or sensory disturbance. Although the pathogenesis is unknown, the currently accepted theory is disproportionate growth between the length of the spinal cord and the length of the spinal column during growth spur, which leads to excessive anterior bulging of the posterior dura during neck flexion. Long term compression of the cervical cord due to tightness of the dural sac during flexion leads to circular micro circulatory changes in the region supplied by the anterior spinal artery causing a stream and neck process of the anterior horn cells. Our study shows Hirayama disease has a male preponderance with 16 to 25 years age group being the most affected. Among the two atypical presentations, one was a seven year old female with claw hand deformity, asymmetric upper limb weakness and muscle atrophy. Another was a 75 year old male patient with unilateral upper limb weakness based on the imaging findings which showed asymmetric lower cord atrophy, intermediary hyper intensity on T2 weighted images and prominence of the posterior epidural space on flexion images. A diagnosis of Hirayama disease was suspected. Upper limb weakness was the most common clinical symptoms seen in around 92% patients. It was unilateral in seven patients and asymmetric bilateral in five patients. Only one patient did not complain of weakness but had unilateral upper limb pain and tremors instead. Distal muscle atrophy was the second most common symptom seen in seven patients. Four had unilateral and three had bilateral weakness. Tremors in the hand was a rare symptom seen unilaterally and bilaterally and one patient each. On MRI in a neutral position, the condition is suspected if there is asymmetric cord flattening and atrophy of the lower cervical cord. The presence of intermediary high signal intensity on T2 weighted images is also presenting feature and MRI with neck flexion is recommended in suspected cases. There is a characteristic forward shifting of the posterior dura during neck flexion. Most patients with Hirayama disease have a recent shaped loss of attachment behind the posterior dura which may show post contrast enhancement. Prominent epidural flow wise may also be seen on flexion. Among our 13 cases, 12 showed the presence of high signal intensity on T2 weighted images and asymmetric cervical cord atrophy on neutral MRI. Only one patient showed cord compression and had not yet developed abnormal cord intensity on presentation. This demonstrates that most cases have progressed to the stage of chronic myelomilacia at the time of initial presentation. A high degree of awareness and suspicion should be exercised to diagnose Hirayama disease at an early stage. Abnormal cord intensities were seen bilaterally in six patients, unilaterally in one patient and subtle hyper intensity in five patients. Abnormal forward shift of posterior dura and cord compression was seen of the C3 C5 level in one patient, C4 C6 level in three patients, C4 C7 level in one patient, C5 C6 level in four patients and C7 C7 level in four patients. On MRI with flexion, all 13 patients showed increased laminodural space. This suggests that increased laminodural distance on flexion images is one of the best imaging features for diagnosing Hirayama disease. We have further classified the extent of increased laminodural space based on the maximum anterior posterior thickness and length of involvement. On flexion MRI, three patients showed increased thickness of 2.1 to 3 mm, seven patients showed thickness of 3.1 to 5 mm and three patients showed thickness of 5.1 to 7 mm. The mean thickness was 4.08 mm with the minimum and maximum thickness being 2.4 mm and 6.7 mm respectively. Next, classifying by length of anterior bulging dura, one patient showed involvement of fewer than two vertebral body segments, eight patients showed involvement of two to four vertebral body segments and four patients showed involvement of more than four vertebral body segments. Precent shared post-contrast enhancement on flexion was seen in all eight patients who underwent the contrast study. Prominent epidural flow voids on flexion were seen in approximately 46% patients. Although Hirayama disease is considered a benign condition, with a stationary course, studies have shown that it can cause serious dysfunction if not treated early. Therefore, restriction of neck flexion, conventionally by neck collar support or by surgical method, is the main treatment for Hirayama disease. The Shiro et al conducted a nationwide epidemiological study of patients with Hirayama disease in Japan, which has information on the number of patients affected per year, distribution of age of onset, neurological symptoms and signs, and effects of conservative treatment. There was a marked male preponderance, the PKG group affected over 17 years, and short slow onset and progression predominantly involving unilateral forearm and hand with cold perises. In a study by Hwang et al, a review of 40 patients with Hirayama disease was done in Taiwan. Overall, 87% patients were male and the mean age of onset was 16.8 years. Progressive distal muscle weakness and atrophy were seen predominantly in the right upper limb with cessation of progression within five years. About one third of the patients had a history of heavy physical activity before the development of symptoms. MRI showed anterior shifting of the posterior dura due to their occurrence after the PKG of the normal age curve. It is postulated that disproportionate growth between the vertebral column and the spinal canal contents could be the underlying cause, and strenuous activity could be a precipitating factor. The conclusion is that Hirayama disease is an uncommon type of cervical myelopathy, seen typically in juvenile males. The occult onset of the distal upper limb weakness and atrophy during puberty, typical MRI features of lower cervical cord atrophy, and the presence of a crescent-shaped enhancing mass in the posterior pideal space are pathognomic of the condition. A few atypical cases can also occur. As described in the study, early diagnosis and treatment are crucial to avoiding serious dysfunction. Thank you.