Magnetic resonance neurography first description

Magnetic resonance neurography (MRN) is the direct imaging of nerves in the body by optimizing selectivity for unique MRI water properties of nerves. It is a modification of magnetic resonance imaging. This technique yields a detailed image of a nerve from the resonance signal that arises from in the nerve itself rather than from surrounding tissues or from fat in the nerve lining. Because of the intraneural source of the image signal, the image provides a medically useful set of information about the internal state of the nerve such as the presence of irritation, nerve swelling (edema), compression, pinch or injury. Standard magnetic resonance images can show the outline of some nerves in portions of their courses but do not show the intrinsic signal from nerve water. Magnetic resonance neurography is used to evaluate major nerve compressions such as those affecting the sciatic nerve (e.g. piriformis syndrome), the brachial plexus nerves (e.g. thoracic outlet syndrome), the pudendal nerve, or virtually any named nerve in the body. A related technique for imaging neural tracts in the brain and spinal cord is called magnetic resonance tractography or diffusion tensor imaging.

History

We have made cross-sectional image “neurograms” in which peripheral nerve has a greater signal intensity than that of other tissue. Neurographic images of the rabbit forelimb were obtained using a spin-echo magnetic resonance imaging (MRI) technique that combines fat suppression and diffusion weighting. After fat suppression the nerve shows up in relative isolation and is brighter than the surrounding tissue due to its longer T2 relaxation time of approximately 50 ms compared to approximately 27 ms for muscle. The addition of pulsed gradients for diffusion weighting of the MR signal further enhances the intensity of the nerve signal relative to that of surrounding muscle tissue. The greater diffusional anisotropy of nerve tissue (D parallel/D perpendicular = 3.1) compared to that of muscle (D parallel/D perpendicular = 1.9) allows further enhancement of the nerve by a subtraction of two diffusion-weighted images, one with the gradients oriented parallel and one with the gradients oriented perpendicular to the nerve orientation. We show that by manipulation of the MRI parameters, either echo time or pulsed gradient strength, the nerves can be made to show up as the most intense feature. This verifies the feasibility of generating three-dimensional “neurographic” images, analogous to angiograms, but which demonstrate the peripheral nerve tracts in apparent isolation 1).
1) Howe FA, Filler AG, Bell BA, Griffiths JR. Magnetic resonance neurography.Magn Reson Med. 1992 Dec;28(2):328-38. PubMed PMID: 1461131.

Update: Neurocysticercosis

Twenty-six patients with cysticercosis of the brain parenchyma were treated with the antihelmintic agent praziquantel (50 mg per kilogram of body weight daily for 15 days). During treatment a strong inflammatory reaction occurred, as evidenced by increased protein and cells in the cerebrospinal fluid. This finding correlated with headache, exacerbation of neurologic symptoms, and edema and inflammation around cystic lesions. After three months of treatment all patients had improved clinically, and 13 (50 per cent) were asymptomatic. The total number of cysts on CT scans had decreased from 152 at the beginning of treatment to 51, and the mean diameter of cysts was reduced by 72 per cent. CT scans showed improvement in 25 of the 26 patients, with total remission of all cysts in nine. Seventeen control patients followed with CT studies for a mean of 9 +/- 2 months had no spontaneous remission of lesions, and in many cases the scans showed worsening during the observation period. Our results indicate that praziquantel is effective in cysticercosis of the brain parenchyma.

Sotelo J, Escobedo F, Rodriguez-Carbajal J, Torres B, Rubio-Donnadieu F. Therapy of parenchymal brain cysticercosis with praziquantel. N Engl J Med. 1984 Apr 19;310(16):1001-7. PubMed PMID: 6708975.

Update: Chiari Type 1

In a series of 71 patients, pain was the commonest symptom (69% of patients); other symptoms included weakness (56%), numbness (52%), and unsteadiness (40%). The presenting physical signs consisted of a foramen magnum compression syndrome (22%), central cord syndrome (65%), or a cerebellar syndrome (11%). Myelography was performed in 69 patients, and was the most useful investigation. Only 23% of plain radiographs were abnormal. In addition to tonsillar descent, the operative findings included arachnoid adhesions (41%) and syringomyelia (32%). All patients underwent suboccipital craniectomy and C1-3 laminectomy. Respiratory depression was the most frequent postoperative complication (14%), and one patient died from sleep apnea. Early postoperative improvement of both symptoms (82%) and signs (70%) was followed by later relapse in 21% of patients, showing an initial benefit following surgery. None of the patients with a cerebellar syndrome deteriorated, whereas 56% of patients with evidence of foramen magnum compression and 66% of those with a central cord syndrome maintained their initial improvement. The authors conclude that posterior fossa decompression appears to benefit some patients, although a significant proportion might be expected to relapse within 2 to 3 years after operation, depending upon the presenting syndrome 1)
1) Paul KS, Lye RH, Strang FA, Dutton J. Arnold-Chiari malformation. Review of 71 cases. J Neurosurg. 1983 Feb;58(2):183-7. PubMed PMID: 6848674.

Taylor-Haughton line revisited

Taylor Haughton line

In 1900 Taylor and Haughton described a technique to define a line on the scalp directly above the central fissure 1)
1. Draw a Nasion-Inion line ( Nasion – Just below Glabella and Inion -External Occipital protruberance)
2. Divide the Nasion-Inion line in to 25%, 50% and 75%
3. Bregma is the point between the 25% and 50% points and Lambda is at 75% point
4. Sylvian fissure is drawn from the orbitotemporal angle (A point of depressin where eyebrow ends) to the 75% point on naso-inion line.
5. Draw a line perpendicular to the root of the zygoma starting at preauricular point
6. Central sulcus is drawn from 54% point on naso-inion line to the point where the sylvian line cuts the perpendicular line
The Taylor-Haughton line was used to identify the central fissure in computed tomography (CT) images. Radiopaque catheters are placed on the scalp on either side of the Taylor-Haughton line prior to CT imaging. The accuracy of the Taylor-Haughton line for identifying the central fissure was also investigated in cadaver brains. The Taylor-Haughton line provides a good approximation of the location of the rolandic fissure 2)
1) Taylor EH,Haughton WS.Some recent researchers on the topography of the convolutions andfissures of thebrain.Trans R Acad Med Ireland 1900;18:511-522
2) Taylor AJ, Haughton VM, Syvertsen A, Ho KC. Taylor-Haughton line revisited. AJNR Am J Neuroradiol. 1980 Jan-Feb;1(1):55-6. PubMed PMID: 6779590.

Murió el neurocirujano Sixto Obrador Alcalde

El doctor Sixto Obrador Alcalde, pionero de la neurocirugía española, falleció , a los 66 años de edad, a consecuencia de un cáncer de páncreas. El doctor Obrador había sido ingresado el martes en el centro de especialidades médicas Ramón y Cajal, cuyo departamento de neurocirugía puso en funcionamiento, y fue asistido en todo momento por el doctor internista Manuel Serrano Ríos.
El doctor Obrador era partidario de una investigación coordinada para lo que pretendía contar con la colaboración directa de neurofisiólogos, neuropatólogos, neuroquímicos, neurólogos, psiquiatras, psicólogos y neuroanestesistas entre otros especialistas médicos.
El lema del neurocirujano fallecido era que todo enfermo del sistema nervioso debe tener en España una buena asistencia neurológica y neuroquirúrgica especializada. Pese a que el aproximadamente centenar de neurocirujanos españoles son discípulos suyos, el doctor Obrador había dicho: «Siempre es necesario tener presente en nuestra labor la humildad e insignificancia de la propia obra. Apenas representa un corto y efímero eslabón de contacto entre pasadas y futuras generaciones. Estamos obligados a crear en todo momento el clima y el ambiente adecuados para el desarrollo futuro de nuestras disciplinas. Por esta razón he consumido mucho tiempo en la enseñanza y divulgación para los médicos.»
Más sobre Sixto Obrador Alcalde

Tumors of the cerebellopontile angle; considerations on 10 cases

Cerebellopontine angle tumor

Cerebellopontine angle (CPA) lesions account for up to 10% of all intracranial tumors.

Types

The most common CPA lesions are vestibular schwannomas (70-80%), meningiomas (10-15%) and epidermoid cysts (5%). CPA tumors are estimated to be the secondary cause for up to 9.9% patients with trigeminal neuralgia.
see Vestibular schwannoma
Cerebellopontine angle meningioma
Cerebellar astrocytoma
Cerebellopontine angle epidermoid cyst
Glomus jugulare associated with the glossopharyngeal nerve
Metastases
Cerebellopontine angle atypical teratoid rhabdoid tumor.
Case series
BENAIM J. [Tumors of the cerebellopontile angle; considerations on 10 cases]. Neurocirugia. 1949-1950;7:105-28. Undetermined Language. PubMed PMID: 14827057. 1)
1) BENAIM J. [Tumors of the cerebellopontile angle; considerations on 10 cases]. Neurocirugia. 1949-1950;7:105-28. Undetermined Language. PubMed PMID: 14827057.

First description of Parsonage-Turner Syndrome

The Parsonage Turner syndrome is named after Maurice Parsonage and John Turner and published in the Lancet by Parsonage and Turner .

The condition, subsequently coined Parsonage-Turner Syndrome, had been previously described in the literature as far back as 1897 with many similar clinical presentations of the syndrome reported prior to the extensive study of the syndrome by Parsonage and Turner.
Parsonage Turner syndrome is also known as acute brachial neuropathy and acute brachial radiculitis.
Other names used are Parsonage–Aldren–Turner syndrome, neuralgic amyotrophy, brachial neuritis, brachial plexus neuropathy, or brachial plexitis.

 
PARSONAGE MJ, TURNER JW. Neuralgic amyotrophy; the shoulder-girdle syndrome. Lancet. 1948 Jun 26;1(6513):973-8. PubMed PMID: 18866299.

Update: Primary motor cortex

www.utdallas.edu_tres_integ_mot2_2_08.jpgThe primary motor cortex in the posterior frontal lobe (Brodmann area 4) was first described by David Ferrier in 1874, who used electrical stimulation to map the cortical areas responsible for movement in monkeys 1).
Since these initial findings, the description of this area has evolved to include the concept of a somatotopic map, wherein different parts of the body are represented individually on the primary motor cortex, as observed by Penfield and Boldrey 2)
 
1) Ferrier D. Experiments on the brain of monkeys – No. I. Proc R Soc Lond. 1874;23:409–30.
2) Penfield W, Boldrey E. Somatic motor and sensory representations in the cerebral cortex of man as studied by electrical stimulation. Brain. 1937;60:389–443