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IMPORTANCE OF AN ACCURATE DIAGNOSIS

Patients experiencing structural Neurological problems generally have high expectations for relief of those problems by their Neurological Surgeons. Part of the challenge for the Neurosurgeon is to identify, as accurately as possible, the precise nature and anatomical configuration of the problem and its relationship to vital adjacent structures.

INITIAL STEPS

Among the "tools" that are available is the ability to listen to the patient as they describe his/her experience with the pathological process and its progression. A carefully conducted Neurological Examination, focused upon the affected part of the Nervous System, allows the Neurosurgeon to objectively document the extent of the functional impairment to that system. The "clues" offered by the patient combined with a skilled "focused" Neurological Examination frequently lead to an accurate presumptive diagnosis.

These efforts are the initial steps towards the goal of diagnostic precision. In the instances where a significant Brain problem is suspected, conditions such as Brain Tumors, Aneurysms, Arteriovenous Malformations (AVM) and Congenital Abnormalities may very well share some common symptoms. An accurate diagnosis of the disease process producing the symptoms becomes an imperative. It is fundamental to successful outcomes for the physician to determine, before surgery, the precise location, size and anatomical configuration of any Tumor, Aneurysm, AVM or Congenital Abnormalities along with its relationship to vital contiguous structures.

The same concepts apply for Neurological problems that are generated by pathological conditions of the Spine and/or Spinal Cord with its Nerve Roots. Any mass lesion (meaning a pathological entity that takes up space within the Skull or Spinal Canal) has the capacity to compress the Brain, Spinal Cord or Nerve Roots against the surrounding bone structure (Skull and/or Vertebral elements). The knowledge and understanding of the precise anatomical location and configuration of the pathological process and its relationship to the Brain, Spinal Cord or Nerve Roots, as well as the surrounding anatomical structures (blood vessels, nerves, bone, etc.) is of considerable importance to the Neurosurgeon, as he/she develops an understanding of the projected natural history (what will happen if one leaves this pathological process untreated), the alternative methods of treatment with their relative risks and limitations, and then arrives at a recommendation for dealing with the process.

NEURO-IMAGING

Neuro-imaging is the term now used for any technology-based investigations of the Brain, Skull, Spinal Cord or Spinal Column that permit "pictures" or images to be produced. Most of these methodologies produce images in "digital" formats that can be manipulated by computer programs to give different sets of image information. While the Neurosurgeon is expected to have the ability to interpret these images, a specialty within the medical discipline of Radiology has developed over the past 35 years, called Neuroradiology. A Neuroradiologist will have completed the training required to become a General Radiologist, after which one to several years are spent in post-graduate Fellowship training to acquire the skills and knowledge required to perform and interpret the various techniques that encompass this field.

NON-INVASIVE TECHNOLOGIES

Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)

We are fortunate to have several non-invasive and painless methods for evaluating and visualizing Brain, Skull, Spinal Cord, Spinal Column, arteries, veins, nerves, joints and muscle in extraordinary detail. Computed Tomography scans (CT scans) and/or Magnetic Resonance Imaging (MRI) scans provide vital information for diagnosing and assessing the patient's unique situation.

Both technologies provide information about bone and soft tissue, however, CT scanning provides exquisite accuracy in the evaluation of bone structure, whereas MRI scanning provides superior details for "soft tissue".

Figure 1A (Left): MRI Scan (Transaxial View) of a Left Petrous "lesion" (Arrow) at level of the Internal Auditory Canals.

Figure 1B (Right): CT Scan (Transaxial View-same patient & level) The bone detail of the "Lesion" (Arrows) is far greater than the MRI Scan.

COMMENT: Compare the two sides of the Skull Base and note the differences in the bone structure.

Figure 2A (Left-Below): MRI Scan (Transaxial View) 38 year old female with a Left Petrous Tumor (Curved Arrow). The details of the 8th Cranial Nerve is apparent as it enters the Internal Auditory Canal (Slender Arrow).

Figure 2B (Center): MRI Scan (Same patient-Gadolinium enhanced). Note the difference "appearance" and characteristics of the tumor (Curved Arrow).

Figure 2C (Right): CT Scan (Transaxial View-same patient). There is no change in the bone underlying the tumor (Curved Arrow). Compare to Figure 2A.

Modern MRI and CT scanning methods have experienced major technological advances that permit the Team of Neurological Physicians and Surgeons to evaluate anatomical details with considerable precision as well as allowing for the examination of some Neurological functions.

CT & MR "Angiography"

CT (CTA) and MRI Angiography (MRA) allow for the evaluation of the blood vessels supplying blood to the Brain and Spinal Cord both within the Skull and Spinal Canal as well as in the neck, as those blood vessels carry blood from the heart to the Brain and Spinal Cord. Functional MRI (FMRI) is becoming available to evaluate certain functional aspects of Brain activity such as speech, movement, memory and thought processes.

Figure 3 A (Left): 3-D CT Angiogram. Advanced computer technology permits the Neuroradiologists & Neurosurgeons to "manipulate" the images as is represented here with the "face" of the patient being "tilted upwards" as compared to

Figure 3B (Right) which represents a "straight Transaxial" view with the nose at the lower portion of each image. The arteries and major veins are clearly identified.

Figure 4 A (Left): MRA (Coronal View) of patient with Right Glossopharyngeal Neuralgia demonstrates unusual tortuosity (Curved arrow) of the Right Posterior Inferior Cerebellar Artery (PICA).

Figure 4 B (Right): Operative Photo (Same Patient) Tortuous PICA (Arrow) compresses and distorts the Right Glossopharyngeal Nerve Root at its entry zone to the Brain Stem.

Figure 5 A (Left): Pre-operative MRI Scan (Gadolinium Enhanced-Transaxial View) demonstrates a very large, partially cystic High Grade Glioma with considerable Right to Left shift of the midline with compression and distortion of the Ventricular system.

Figure 5B (Center): 2 year Post-operative MRI Scan (Gadolinium Enhanced-Transaxial View). There is no evidence of residual tumor after an extensive Right Frontal Lobectomy, aggressive tumor resection & modern chemotherapy/radiation.

Figure 5C (Right): 2 year Post-operative Functional MRI (FMRI) Scan (Transaxial View-Same Patient-almost identical "Slice")

PET/CT Scan

Positron Emission Tomography is a radioisotope based technology that has now been combined with CT scanning. The combination of these two methodologies has permitted a considerable increase in the accuracy of isotope-based scans which are mainly used for evaluating cancer conditions.

Figure 6: PET/CT Scan. The "dark" areas represent increased "uptake" of the radioisotope indicating metastatic tumor (Arrows).

INVASIVE TECHNOLOGIES

Angiography (Catheter-based)

There are times when certain disease processes require even more accurate anatomical understanding such as occurs with blood vessel problems inside the Skull or Spinal Canal. In cases of Aneurysms, AVM's or Skull Base Tumors, the precision of the CT and MRI may be insufficient. In these situations, Cerebral Angiography may be required. This is an "invasive" test conducted by a Neuroradiologist. A catheter is inserted into a blood vessel, usually in the groin, and threaded, under x-ray monitoring, into the large artery (Aorta) in the abdomen and chest, until it reaches the blood vessels that supply blood to the Brain. The catheters and techniques are exquisitely accurate. A dye substance is injected into the blood vessels and x-rays obtained resulting in high resolution images of the anatomy.

Figure 7A (Left): Vertebral Angiogram (Lateral View) of a Basilar Artery "Tip" Aneurysm (Arrow).

Figure 7B (Below): Post-operative Vertebral Angiogram (Same patient). The Aneurysm has been successfully "clipped" (Arrow) with preservation of the vital adjacent vessels.

Myelogram/Post-myelographic CT Scan

For conditions that affect the Spine, Spinal Cord and Spinal Nerves another "invasive" type of test may become necessary. This test is called a Myelogram and is generally regarded as the "gold standard" examination for many Spinal conditions. Our philosophy is to "AVOID INVASIVE PROCEDURES, if possible" since MRI and CT are sufficient for most cases. Nevertheless, there are many circumstances where the information provided by this study is invaluable in identifying the precise anatomical abnormalities (well beyond the capability of MRI and/or CT alone). This becomes an imperative for very precise pre-operative planning and success on a long-term basis.

Myelograms are usually conducted by the Neuroradiologist who inserts a small needle into the Spinal Canal and injects a fluid dye substance which can then flow within the Spinal Canal and be "photographed" with several x-ray techniques including CT scanning.

Figure 8A (Left): MRI Scan (Sagittal View) Multi-level Cervical Spinal Stenosis

Figure 8B (Right): Post-myelographic CT Scan (Sagittal View) The bone details are far more graphically demonstrated on this CT Scan than the comparable MRI Scan.

COMMENT: These DETAILS are critically important in the planning of the surgical repair of problems such as this.

Your Neurosurgeon's diagnostic accuracy is directly related to having the vital information provided by these investigations.


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This page last edited on 2/19

All content ©2016 by Neurosurgical Consultants, P.A.
Author, Martin L. Lazar, MD, FACS
All Rights Reserved. See Usage Notices.