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They have been observed in schistocytic haemo Inherited lytic anaemias including microangiopathic haemolytic Heterozygotes for the McLeod phenotype anaemia cheap imitrex 50 mg free shipping spasms before falling asleep, in disseminated intravascular coagulation and Pyruvate kinase defciency in renal disease order imitrex 50mg with visa muscle relaxant spray, e cheap 25mg imitrex otc spasms poster. They are believed to give rise to a keratocyte Myxoedema and panhypopituitarism through rupture of the vacuole discount imitrex 50mg with mastercard muscle spasms 9 weeks pregnant. They are most charac teristic of iron defciency, but are also present in β tha ∗Some cases have acanthocytes. The flm also shows polychromasia and a nucleated red leagues and the British Journal of Haematology . Schistocytes are formed either by fragmentation of schistocytes may be microdiscocytes as well as micro abnormal cells, e. An uncommon form of following mechanical, toxin‐ or heat‐induced damage red cell fragment, a linear or flamentous structure, is of previously normal cells (Fig. The on mechanical damage, schistocytes often coexist with commonest causes of schistocyte formation are micro keratocytes. Oth angiopathic and mechanical haemolytic anaemias, ers have been left with too little membrane for their collectively known as schistocytic haemolytic anaemia. For this pur pose they advise the inclusion of fragments with sharp angles and straight borders, small crescents, helmet cells, keratocytes and microspherocytes, the latter only in the presence of other characteristic cells . Quan tifcation is per 1000 erythrocytes, with more than 1% schistocytes being regarded as signifcant. Quantifca tion is only relevant when schistocytosis is the domi nant morphological abnormality. This can be used for screening for schistocytic haemolytic anaemias, although false negative results may be obtained when Fig. Target cells Target cells have an area of increased staining, which appears in the middle of the area of central pallor (Fig. Target cells are formed as a consequence of there being redundant membrane in relation to the volume of the cytoplasm. In vivo they are bell‐shaped and this can be demonstrated on scanning electron microscopy (Fig. They fatten on spreading to form the characteristic cell seen on light microscopy. Target cells may be microcytic, normocytic or macro cytic, depending on the underlying abnormality and the mechanism of their formation. When target cells are Haemoglobin C disease formed as a result of plasma lipid abnormalities, they Sickle cell anaemia revert to a normal shape on being transfused into a Compound heterozygosity for haemoglobin S and haemoglobin C Haemoglobin D disease subject with normal plasma lipids. If changes in mem Haemoglobin O‐Arab disease brane lipids that would normally cause target cell for mation occur in patients with spherocytosis, the cells Conditions that may be associated with moderate or small become more disciform; this phenomenon may be numbers of target cells Parenchymal liver disease observed when a patient with hereditary spherocyto Splenectomy and other hyposplenic states sis develops obstructive jaundice. Haemoglobin C trait An alternative mechanism of target cell formation Haemoglobin S trait is a reduction of cytoplasmic content without a Haemoglobin E trait and disease proportionate reduction in the quantity of mem Haemoglobin Lepore trait brane. This is the mechanism of target cell formation β thalassaemia minor, intermedia and major in a group of conditions such as iron defciency, Haemoglobin H disease Iron defciency thalassaemias and haemoglobinopathies in which tar Sideroblastic anaemia get cells are associated with hypochromia or micro Hereditary xerocytosis (dehydrated variant of hereditary cytosis. Target cells are much less numerous in iron stomatocytosis)  defciency than in thalassaemias. The reason for this Analphalipoproteinaemia  and hypoalphalipoproteinaemia  is not clear. Stomatocytes are cells that, on a stained blood Target cells may be formed because of an excess flm, have a central linear slit or stoma (Fig. On scanning electron micros in obstructive jaundice, severe parenchymal liver copy or in wet preparations with the cells suspended disease and hereditary defciency of lecithin‐chol in plasma they are cup‐ or bowl‐shaped (Fig. The end stage of a discocyte–stomato esterol so that changes in the membrane lipids are cyte transformation is a spherostomatocyte. In liver disease, stoma cholesterol, with a proportionate increase in lecithin tocyte formation has been attributed to an increase and with a decrease in ethanolamine. In hereditary spherocytosis and autoimmune Morphology of blood cells 93 chlorpromazine exposure can cause stomatocytosis in vivo as well as in vitro since an association has been observed . Stomatocytosis in hereditary high red cell membrane phosphatidylcholine haemolytic anaemia is associated with numerous target cells ; this condition is now thought to be identical to hereditary xerocytosis . Stomatocytosis has been associated with some cases of hereditary haemolytic anaemia associated with adenosine deaminase over‐ Fig. Increased stoma tocytes have been reported in association with target cells in a single patient with familial hypobetalipo proteinaemia , but in the published photograph the target cells are much more convincing than the stomatocytes. An increased incidence of stoma tocytosis has been reported in healthy Mediterranean (Greek and Italian) subjects in Australia . This condition, designated Mediterranean stomatocyto sis/macrothrombocytopenia, is now known to be a manifestation of hereditary phytosterolaemia . A sickle cell is a very specifc type of cell that is con Stomatocytes have been associated with a great var fned to sickle cell anaemia and other forms of sickle iety of clinical conditions [119,120] but an aetiologi cell disease. Sickle cells are crescent‐ or sickle‐shaped cal connection has not always been established. The characteristic shape commonest cause of stomatocytosis is alcohol excess is very apparent on scanning electron micrography and alcoholic liver disease; in these cases there is (Fig 3. The blood flm in sickle cell anaemia may often associated macrocytosis and in those with very also show boat‐ or oat‐shaped cells (Fig. They are also common in erythroleukaemia Howell–Jolly body is a fragment of nuclear material. Similar cells can be seen in oxidant‐induced hae arise by karyorrhexis (the breaking up of a nucleus) or by molysis, when they result from removal of two adjacent incomplete nuclear expulsion, or can represent a chromo Heinz bodies. Searching for Howell–Jolly bodies is a reliable tech nique for screening for signifcant hyposplenism, although a phase‐microscopy pitted cell count is more sensitive and will also detect milder impairment of splenic function . They are composed of aggregates of ribo somes; degenerating mitochondria and siderosomes may be included in the aggregates, but most such inclusions are negative with Perls acid ferrocyanide stain for iron. Increased numbers are seen in the presence of thalassaemia minor (particularly β thalassaemia trait and Fig. Some Howell–Jolly bodies are found in general (including congenital dyserythropoietic anaemia, erythrocytes within the bone marrow in haematologically sideroblastic anaemia, erythroleukaemia and primary mye normal subjects but, since they are removed by the spleen, lofbrosis), liver disease and poisoning by heavy metals such they are not seen in the peripheral blood. Baso the blood following splenectomy and are also present in philic stippling is a prominent feature of hereditary def other hyposplenic states, including transient hyposplenic ciency of pyrimidine 5’‐nucleotidase , an enzyme that states resulting from reticulo‐endothelial overload. Inhibition of this enzyme can be a normal fnding in neonates (in whom the spleen may also be responsible for the prominent basophilic stip is functionally immature). Pappenheimer bodies in a haematologically normal subject, small numbers of Pappenheimer bodies (Fig. In pathological conditions, such as lead poisoning numbers in erythrocytes; they often occur in small clus or sideroblastic anaemia, Pappenheimer bodies can also ters towards the periphery of the cell and can be dem represent iron‐laden mitochondria or phagosomes. They are composed of ferritin patient has also had a splenectomy they will be present in aggregates, or mitochondria or phagosomes containing much larger numbers.
Generate a unique identifer so that the new hardware or software can communicate with outside systems Concept: One of the frst steps in acquiring new hardware or software for any laboratory information system is determining the functional requirements—what tasks or goals the software is supposed to accomplish order 25mg imitrex visa back spasms 34 weeks pregnant. Answer: C—Of the choices offered purchase imitrex 50 mg with amex muscle relaxant methocarbamol addiction, this choice would be the frst step in the implementation of new hardware or software discount imitrex 50 mg on-line spasms detoxification. Finally order imitrex 50mg without prescription muscle relaxant used during surgery, once the desired vendor is chosen, the contract can then be negotiated (Answer A). A unique identifer generated by the laboratory information system in order to interface with outside systems would be one of the fnal steps in the implementation of new hardware or software (Answer E). Blood product containers/bags use both 1D linear barcodes and 2D barcodes, while smaller blood collection tubes beneft from the use of 2D barcodes alone. Which of the following choices represent an advantage of 2D barcodes over linear 1D barcodes? They are able to store more information and ft on smaller labels due to their smaller footprint. However, some 2D scanners can also scan 1D barcodes, which is termed backwards compatibility. In general, 2D barcodes scan at speeds slightly slower than 1D barcodes and though they are not yet equal, technological advances have closed the scanning speed gap in recent years (Answer B). The current standard recognizes Code 128 for 1D barcodes and Data Matrix for 2D barcodes. A Code 128 barcode has six sections: • Quiet zone • Start character • Encoded data • Check character • Stop character • Quiet zone 450 19. Error correction codes are built into Data Matrix barcodes so that if one or more individual modules are damaged, the code can still usually be read. Codabar is a linear 1D barcode technology developed by Pitney-Bowes and was previously used before Code 128 on blood bank labels. It was designed to be read even when printed on low- resolution dot matrix printers. Codabar technology fell out of favor to Code 128 because more data can be stored in a smaller footprint with Code 128 barcodes. It uses a series of application identifers, such as (12) (see earlier mentioned example) to include additional data. MaxiCode is a bar code technology originally created and used by the United Parcel Service. Its most frequent application is in the tracking of packages, and it is available for use in the public domain. Sets a limit to only one bar code being read at a time, reducing the number of reading errors B. Uniformity of labeling by different collection centers, which allows better traceability of blood components C. Single-density coding of numeric characters, which permits encoding of more information in a given space D. This allows for better traceability of blood and blood components, even across international lines. This information must be presented in both eye-readable and machine-readable format. Additional special message labels may also be attached to blood component containers. These include “hold for further manufacturing,” “for emergency use only,” “for autologous use only,” “not for transfusion,” “irradiated,” “biohazard,” “from a therapeutic phlebotomy,” and “screened for special factors. The base label includes the Container Manufacturer Identity, Catalog Number, and the Container Lot Number. This information must be presented in both eye-readable and machine-readable format. Additional special message labels may also be attached to blood component containers. These include “hold for further manufacturing,” “for emergency use only,” “for autologous use only,” “not for transfusion,” “irradiated,” “biohazard,” “from a therapeutic phlebotomy,” and “screened for special factors. The next two characters, shown at a 90-degree angle rotated clockwise, are fag characters. The use of fag characters (for process control and/or check characters) is optional. The other choices are incorrect as follows: Answer A represents the Facility Identifcation Number, Answer B is the nominal year of collection, Answer D is the fag character, and Answer E is the check character (Fig. Correlation database Concept: A relational database is organized based on the relational model of data that is displayed in tables. The asterisk (*) in the select list indicates that all columns of the results table should be included in the result set. Pathology InformatIcs 455 A parallel database system (Answer A) improves performance through running simultaneous actions (parallelization), such as queries or the loading of data sets via the use of multiple database server processors. A virtual private database (Answer B) is part of a larger database such that only a small subset of data from the larger database is visible or accessible by a subset of users. In an object database (Answer D), information is presented in the form of objects. In a correlation database (Answer E), a value-based storage architecture is used such that each unique database entry is recorded 1 time and the indexing system is automatically generated. Which of the following universal standards uses a database record with the following six felds: property, time, system, type of scale, type of method, and component? Each data record includes six felds for each test or measurement: • Component—what is being measured or observed (e. It includes a fle format defnition and a network communications protocol (Answer E). A piece of equipment in the blood bank has malfunctioned, and you are called to provide more information on the nature of the problem. Pathology InformatIcs 457 The earlier mentioned code selects data from the results table where the hemoglobin value is greater than 7 and then orders the results according to the ordering physician. The asterisk (*) in the select list indicates that all columns of the Results table should be included in the result set. This layer is particularly important in the health care setting due to Health Level Seven (see Question 17). The Physical Layer (Layer 1) defnes the physical and electrical blueprint of the data connection. The Data Link Layer (Layer 2) transmits data between two different nodes that are connected by the physical layer (Answer E). The Transport Layer (Layer 4) transfers data from a source to a destination through a network. The Session Layer (Layer 5) manages communication sessions, or continuous two-way data transmissions between two nodes (Answer A). The Presentation Layer (Layer 6) translates data between a networking service and an application.
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An ophthalmologist should be 726 consulted immediately if there is any doubt about the diagnosis generic 25 mg imitrex overnight delivery muscle relaxant guidelines. Chest x-ray (sarcoidosis) Case Presentation #78 A 17-year-old black boy presents to the emergency room with redness of his left eye generic imitrex 25mg on-line spasms right side of stomach. Utilizing your knowledge of anatomy purchase imitrex 50 mg with amex muscle relaxant alcohol addiction, what is your differential diagnosis at this point? Further questioning reveals that he has had intermittent bloody diarrhea for several months order imitrex 25mg without prescription muscle relaxant non prescription. N—Neurologic disorders associated with restless leg syndrome include uremic or diabetic neuropathy, Parkinson disease, and multiple sclerosis. T—Toxic causes of this disorder include barbiturates, benzodiazepines, caffeine, and tricyclic antidepressants. A neurologist should be consulted before ordering these expensive diagnostic tests. It is almost invariably due to a wound infection with tetanus but may also give the appearance of a fixed grin. Approach to the Diagnosis Careful examination of the trunk and extremities for a wound infection is extremely important. If the patient is not stripped down, the clinician can miss a tetanus infection caused by dirty needles in drug addicts. A history of mental illness should alert one to attempted suicide with strychnine. M—Mental disorders such as pseudoneurosis can be associated with diffuse scalp tenderness. I—Inflammation would bring to mind herpes zoster, pediculosis, tinea capitis, cellulitis, an infected sebaceous cyst, and impetigo. N—Neurologic disorders associated with a tender scalp include temporal arteritis, occipital nerve entrapment, trigeminal neuralgia, and neoplasms that involve the cranium and meninges (i. Approach to the Diagnosis Most skin conditions should be easily diagnosed by inspection. A sedimentation rate and biopsy of the superficial temporal artery will diagnose temporal arteritis. If occipital nerve entrapment is suspected, a nerve block should be done to confirm the diagnosis. M—Malformation prompts the recall of osteogenesis imperfecta, congenital hemivertebra, Marfan syndrome, and arthrogryposis. The I should also remind one of idiopathic scoliosis, responsible for 80% of the cases. T—Trauma should facilitate the recall of thoracolumbar sprain, compression, fracture, and herniated disk. S—Systemic diseases associated with scoliosis include Paget disease, pulmonary fibrosis, and Ehlers–Danlos syndrome. Approach to the Diagnosis To diagnose scoliosis, have the patient bend over, and there will be asymmetry in the height of the scapulae (Adam test). Most causes of scoliosis will require only an x-ray of the spine to clarify the diagnosis. Tracing the nerve endings in the face or extremities to the brain we have the peripheral nerves, nerve plexus, nerve roots, spinal cord, brain stem, and cerebrum. Now cross-index these structures with the various etiologies (vascular, inflammatory, neoplastic, etc. Peripheral nerve—This structure should prompt the recall of carpal tunnel syndrome, ulnar entrapment in the hand or elbow, 730 and diffuse peripheral neuropathy (diabetes, nutritional disorders, etc. Nerve plexus—This structure should suggest brachial plexus neuritis, sciatic neuritis, brachial plexus compression by a Pancoast tumor or thoracic outlet syndrome, or lumbosacral plexus compression by a pelvic tumor. Nerve roots—This would facilitate the recall of space-occupying lesions of the spinal cord (e. It would also help to recall tabes dorsalis, herniated disk disease, osteoarthritis, cervical spondylosis, spinal stenosis, and spondylolisthesis. Spinal cord—Lesions in the spinal cord that cause sensory loss include space-occupying lesions, syringomyelia, pernicious anemia, multiple sclerosis, and Friedreich ataxia, acute traumatic or viral transverse myelitis, and anterior spinal artery occlusion may also cause sensory loss. Brain stem—This should prompt the recall of brain stem tumors, abscess and hematomas, multiple sclerosis, syringobulbia, encephalomyelitis, basilar artery, thrombosis, posterior inferior cerebellar artery occlusion, and neurosyphilis. Cerebrum—Space-occupying lesions of the cerebrum, cerebral hemorrhage, thrombosis, or embolism should be considered here. Encephalitis, toxic encephalopathy, and multiple sclerosis are less likely to cause significant sensory loss if the lesions are confined to the cerebral cortex. Approach to the Diagnosis The neurologic examination will help to determine the location of the lesion. Peripheral neuropathy presents with diffuse distal loss of sensation to all modalities. Nerve root involvement will present with sensory loss in a radicular distribution; spinal cord involvement will be associated with a sensory level. Sensory loss to pain and temperature on one side of the face and the opposite side of the body is typical of posterior inferior cerebellar artery occlusion. If there is only loss of vibratory and position sense, look for pernicious anemia or a cerebral tumor. The muscles and tendons come next, and epidemic myalgia and the myalgias secondary to many infectious diseases lead the list. However, trichinosis, dermatomyositis, fibromyositis, and trauma must always be considered. Proceeding to the blood vessels, keep in mind thrombophlebitis, Buerger disease, vascular occlusion from periarteritis nodosa, and other forms of vasculitis. This should be considered traumatic because in most cases the torn ligamentum teres rubs the bursa and causes the inflammation. Interestingly enough, aside from gout, the bursae are rarely involved in other conditions. Osteoarthritis, rheumatoid arthritis, gout, lupus, and various bacteria all may involve this joint, but dislocation of the shoulder, fractures, and frozen shoulder should be considered. Neurologic causes are not the last to be considered just because anatomically they come last. The brachial plexus may be compressed by a cervical rib, a large scalenus anticus or pectoralis muscle, or the clavicle (costoclavicular syndrome). When the cervical sympathetics are irritated or disrupted, a shoulder–hand syndrome develops. The cervical spine is the site or origin of shoulder pain in cervical spondylosis, spinal cord tumors, tuberculosis and syphilitic osteomyelitis, ruptured disks, or fractured vertebrae. Thus, coronary insufficiency, cholecystitis, Pancoast tumors, pleurisy, and subdiaphragmatic abscesses should be ruled out.
Direct trauma to the spinal cord coincides with the posterior most aspect of the ligamentum with catastrophic consequences (quadriplegia) has also been ﬂavum (Fig buy imitrex 50mg with amex zanaflex muscle relaxant. The needle tip can be safely advanced described 25 mg imitrex free shipping muscle relaxant end of life, particularly in heavily sedated patients (Fig buy imitrex 25 mg fast delivery spasms perineum. Caution should also needle tip is within the epidural space and contrast has been be taken to avoid interlaminar epidural injection at any level injected (Fig discount imitrex 25 mg with mastercard muscle relaxant antidote. Digital sub- rounding the spinal cord within the thecal sac occurs in high- traction technology can also be extremely useful in ensuring grade spinal stenosis, particularly that due to a large central injectate has spread to the level of pathology (Fig. As with interlaminar epidural Once epidural needle position has been conﬁrmed, a solu- injection at all vertebral levels, epidural bleeding or infection tion containing steroid diluted in preservative-free saline (80 can occur. Epidural hematoma or abscess can lead to signiﬁ- mg of methyl prednisolone acetate or the equivalent diluted cant spinal cord compression. Interlaminar injection should in 5 mL total volume) is injected, and the needle is removed. Complications Thoracic Epidural Injection Dural puncture with subsequent postdural puncture head- Positioning ache can occur during cervical interlaminar epidural injection. Although cervical epidural blood patch using a small volume The patient lies prone, with the head turned to one side of autologous blood has been described, most practitioners will (Fig. The C-arm is rotated 40 to 50 degrees caudally manage postdural puncture headache following cervical epi- from the axial plane without any oblique angulation. Chapter 5 Interlaminar Epidural Injection 47 Styloid process Occiput Posterior arch of C1 Mandible C2 Spinous process of C2 C3 C4 Lateral masses “J-Point”: (facet column) anterior extent of C3, C4, and C5 spinous processes Contrast in posterior epidural space A B Figure 5-12. Lateral radiograph of the upper cervical spine during interlaminar cervical epidural injection. The contrast can be seen as a thin stripe toward the poste- rior aspect of the spinal canal, adjacent to the anterior-most aspect of each spinous pro- cess. Although lateral radiographs near the cervicothoracic junction are difﬁcult to interpret because of the overlying structures of the thorax and upper extremities, lateral radiographs of the superior cervical spine can be used to verify epidural placement. Contrast around the right C8 spinal nerve and extending laterally through the inter- vertebral foramen A B Figure 5-13. Note the contrast spread nearly two vertebral levels above and below the level of injection and outlining the spinal nerves on both sides. Radiolucent area cephalad and to right of the needle tip is an air bubble in the contrast medium. Although a midline approach can be used at low thoracic levels, the spinous processes are angled too steeply to allow for true coaxial needle placement at the midthoracic levels. Care must be taken to keep the needle tip over the margin of the lamina until the bone is gently con- tacted. The periosteum should then be anesthetized with an additional 1 mL of 1% lidocaine and a syringe contain- ing 1 to 3 mL of preservative-free saline attached to the needle. Because the needle is unlikely to lie within the interspinous ligament Figure 5-14. The injection was performed in an proximity of the spinal cord are essential during thoracic unresponsive patient under deep sedation. After the T2-weighted signal within the spinal cord suggests edema, most needle tip enters the epidural space, the position is con- likely a result of needle entry and direct injection within the sub- ﬁrmed by injecting 1 to 1. The patient suffered permanent, par- contrast (iohexol 180 mg per mL), and contrast spread is tial loss of sensory and motor function in all extremities. Lateral imaging of the thoracic spine is hindered by the overlying structures of the thorax (Fig. Once epidural needle position Block Technique has been conﬁrmed, a solution containing steroid diluted The skin and subcutaneous tissues ∼1 cm lateral and 1 cm in preservative-free saline (80 mg of methyl prednisolone caudal to the interspace where the block is to be carried acetate or the equivalent diluted in 5 mL total volume) is out are anesthetized with 1 to 2 mL of 1% lidocaine. Chapter 5 Interlaminar Epidural Injection 49 T1 C7 T1 T2 T2 T3 T3 T4 T4 T5 T5 T6 T6 T7 T7 T8 T8 10 – 15° T9 T9 from 50 – 60° sagittal T10 T10 plane T11 T11 T12 T12 L1 Figure 5-16. Position and angle of needle entry for thoracic interlaminar epidural injection (paramedian approach). Starting ∼1 cm below the interspace and 1 cm lateral to the spinous processes, an 18- or 20-gauge Tuohy needle is advanced 10 to 15 degrees toward midline with 50 to 60 degrees of cranial angulation from the axial plane. Complications Lumbar Epidural Injection Dural puncture with subsequent postdural puncture head- Positioning ache can occur during thoracic interlaminar epidural injec- The patient lies prone with the head turned to one side tion. A pillow is placed under the mid and lower volume of autologous blood has been described, most prac- abdomen to reduce the lumbar lordosis and increase the titioners will manage postdural puncture headache follow- separation between adjacent spinous processes. The C-arm ing thoracic epidural injection conservatively with ﬂuids and is rotated 15 to 20 degrees caudally from the axial plane oral analgesics. This allows for good visu- dural puncture is high (50% or more of patients), approach- alization of the interlaminar space and needle advancement ing that following lumbar puncture. Block Technique The level of sedation during this procedure should allow for direct conversation between the practitioner and the patient The skin and subcutaneous tissues overlying the interspace to ensure that the patient can report contact with neural ele- where the block is to be carried out are anesthetized with ments before signiﬁcant traumatic injury occurs. An 18- or 20-gauge Tuohy needle should also be taken to avoid interlaminar epidural injection is placed through the skin and advanced 1 to 2 cm until it at any level where there is effacement of the epidural space is ﬁrmly seated in the interspinous ligament. A ﬁrm knowledge of the anatomy of adjacent sac such as that which can occur in high-grade spinal ste- structures, as well as the proximity of the thecal sac and cauda nosis, particularly that due to a large central or paramedian equina, is essential during lumbar interlaminar epidural injec- disc herniation). The ﬂuoroscope is then moved to a lateral all vertebral levels, epidural bleeding or infection can occur. A syringe containing 1 to 3 mL of preser- or postponed in those receiving anticoagulants. Three-dimensional reconstruction computed tomography of the low thoracic spine as viewed from the poste- rior approach used for thoracic interlaminar injection. B: Anterior-posterior radiograph of the thoracic spine during thoracic interlaminar injection (paramedian approach). An 18-gauge Tuohy needle is in position between the T12 and L1 laminae just to the right of midline. The needle should ﬁrst be advanced, keeping the needle tip over the superior margin of the lamina bounding the inferior aspect of the interspace to be entered (in this example, the superior margin of the lamina of L1 to the right of midline). The needle is advanced until it gently touches the lamina where it joins with the spinous process. This paramedian approach is often necessary at thoracic levels because of the steep angulation of the spinous processes. Chapter 5 Interlaminar Epidural Injection 51 Interspinal ligament Spinous process Epidural Ligamentum space flavum Subarachnoid space Posterior primary ramus of spinal nerve Anterior primary Lung Figure 5-18. The epidural needle is advanced toward the Dorsal midline using a paramedian approach and traverses root the ligamentum ﬂavum to enter the dorsal epidural ganglion Aorta space in the midline. The normal epidural space is ∼3 (T8) to 5 mm wide (from the ligamentum ﬂavum to the dura mater in the axial plane). Note the proximity of Esophagus the underlying spinal cord during thoracic epidural injection.